Internet Draft F. Gennai
Intended status: Standards track A. Shahin
Expires: April 2009 ISTI-CNR
C. Petrucci
A. Vinciarelli
CNIPA
October 2008
Certified Electronic Mail
draft-gennai-smime-cnipa-pec-01.txt
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Copyright Notice
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Copyright (C) The IETF Trust (2008).
Abstract
Since 1997, the Italian Laws have recognized electronic delivery
systems as legally usable. After 2 years of technical tests, in
2005 the characteristics of an official electronic delivery
service, named certified electronic mail (in Italian "Posta
Elettronica Certificata") were defined, giving the system legal
value.
Design of the entire system was carried out by the National
Center for Informatics in the Public Administration of Italy
(CNIPA), followed by efforts for the implementation and testing
of the service. The CNIPA has given the Italian National
Research Council (CNR), and in particular The Institute of
Information Science and Technologies at the CNR (ISTI), the task
of running tests on providers of the service to guarantee the
correct implementation and interoperability. This document
describes the certified email system adopted in Italy. It
represents the system as it is at the moment of writing,
following the technical regulations that were written based upon
the Italian Law DPR. November 2, 2005.
Table of Contents
1. Introduction ................................................ 4
1.1. Scope ..................................................... 4
1.2. Notational Conventions .................................... 5
1.2.1. Requirement Conventions ................................. 5
1.2.2. Acronyms ................................................ 5
1.2.3. Terminology and Definitions ............................. 5
2. PEC model ................................................... 9
2.1. System-generated messages ................................. 9
2.1.1. Message types ...........................................11
2.2. Basic structure ...........................................14
2.2.1. Access point ............................................14
2.2.2. Incoming point ..........................................16
2.2.3. Delivery point ..........................................18
2.2.4. Storage .................................................19
2.2.5. Provider service mailbox ................................19
2.3. Log .......................................................19
3. Message processing ..........................................20
3.1. Access point ..............................................20
3.1.1. Formal checks on messages ...............................20
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3.1.2. Non-acceptance notification due to one or more
formal exceptions........................................21
3.1.3. Non-acceptance notification due to virus detection.......22
3.1.4. Acceptance notification .................................23
3.1.5. Transport envelope ......................................23
3.1.6. Timeout delivery error notification .....................25
3.2. Incoming point ............................................27
3.2.1. Take in charge notification .............................27
3.2.2. Anomaly envelope ........................................28
3.2.3. Virus detection notification ............................29
3.2.4. Virus-induced delivery error notification................30
3.3. Delivery point ............................................31
3.3.1. Checks on incoming messages .............................31
3.3.2. Delivery notification ...................................31
3.3.3. Non-delivery notification ...............................36
4. Formats .....................................................37
4.1. Temporal reference ........................................37
4.2. User date/time ............................................37
4.3. Attachments ...............................................37
4.3.1. Message body ............................................37
4.3.2. Original message ........................................38
4.3.3. Certification data ......................................38
4.4. Certification data scheme .................................38
4.5. PEC providers directory scheme ............................41
5. Example: Complete transaction between 2 PEC domains..........48
6. Security-related aspects ....................................49
6.1. Digital signature .........................................49
6.2. Authentication ............................................49
6.3. Secure interaction ........................................50
6.4. Virus .....................................................50
6.5. S/MIME certificate ........................................51
6.5.1. Provider-related information (subject) ..................51
6.5.2. Certificate extensions ..................................51
6.5.3. Example .................................................52
6.6. PEC providers directory ...................................57
7. PEC system client technical and functional prerequisites ....57
8. Security Considerations .....................................57
9. IANA Considerations .........................................58
10. References .................................................58
10.1. Normative References .....................................58
11. Acknowledgments ............................................59
APPENDIX A: Italian fields and values in English ...............60
Author's Addresses .............................................61
Intellectual Property Statement ................................61
Disclaimer of Validity .........................................62
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1. Introduction
Since 1997, the Italian Laws have recognized electronic delivery
systems as legally usable. After 2 years of technical tests, in
2005 the characteristics of an official electronic delivery
service, named certified electronic mail (in Italian Posta
Elettronica Certificata, from now on "PEC") were defined, giving
the system legal value.
1.1. Scope
To ensure secure transactions over the Internet, cryptography
can be associated with electronic messages in order to provide
some guarantee on sender identity, message integrity,
confidentiality, and non-repudiation of origin. Many end-to-end
techniques exist to accomplish such goals. But, even though end-
to-end cryptography offers a high level of security, it has a
downside; the need for an extensive penetration of technology in
the society, since it would be essential for every user to have
a couple of symmetric keys and a certificate, signed by a
Certification Authority, associated with the public key. Along
with that, users would need to have an adequate amount of
knowledge regarding the use of such technology.
PEC on the other hand offers the digital signing of messages
through applications running directly on the servers, thus
avoiding the complexity end-to-end systems bring about. By doing
so, the user needs only have an ordinary mail client with which
to interact. The downside is that the level of security drops,
since the protection does not cover the entire transaction.
Nonetheless, application is simpler and does not require
specific user skills, making it easily more widespread among
users.
A provider for such a service must follow certain regulations
and undergo several tests of compatibility and interoperability
before it can be considered legally functional.
This document describes PEC's Technical Regulations and
functionality. It presents the details of the protocol and the
messages that are sent between service providers. It is meant to
be an introduction to the system the Italian government has
adopted for the sending and receiving of certified emails,
giving them a legal value equivalent to that of Registered Mail
with Return Receipt.
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1.2. Notational Conventions
1.2.1. Requirement Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described
in [REQ].
1.2.2. Acronyms
CMS: Cryptographic Message Syntax
CNIPA: National Center for Informatics in the Public
Administration of Italy (Centro Nazionale per
l'Informatica nella Pubblica Amministrazione)
CNR: Italian National Research Council (Consiglio Nazionale
delle Ricerche)
CRL: Certificate Revocation List
CRL DP: Certificate Revocation List Distribution Point
DNS: Domain Name Service
DTD: Document Type Definition
FQDN: Fully Qualified Domain Name
ISTI: The Institute of Information Science and Technologies at
the CNR (Istituto di Scienza e Tecnologie
dell'Informazione "A.Faedo")
LDAP: Lightweight Directory Access Protocol
LDIF: LDAP Data Interchange Format
MIME: Multipurpose Internet Mail Extensions
PEC: Certified Electronic Mail (Posta Elettronica Certificata)
S/MIME: Secure/MIME
SMTP: Simple Mail Transfer Protocol
TLS: Transport Layer Security
XML: eXtensible Markup Language
1.2.3. Terminology and Definitions
Acceptance notification: Emitted by the sending access point to
its user upon the latter's request to send a PEC message. This
occurs when checks on said message go smoothly, and serves to
notify the user that the provider will be taking care of sending
the PEC message to its intended destination(s). It contains
certification data and is signed using the sender PEC provider's
key.
Access point: Is what interfaces the user to the rest of the PEC
system. It provides access services for user identification, as
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well as sending and reading PEC messages. An access point also
performs virus checks (on outgoing messages), and inserts the
original message into a transport envelope. The messages it can
emit are:
o acceptance notifications.
o non-acceptance notifications, either due to some formal
exception or virus presence.
Anomaly envelope: When a message contains errors or is not a PEC
message it MUST be inserted inside an anomaly envelope to
highlight the irregularity to the receiving user. The envelope
is signed using the receiver PEC provider's key.
Brief delivery notification: A type of delivery notification
that contains the original message, certification data, and hash
values of the attachments that were included in the original
message, if any.
Certification data: A set of data, certified by the sender's PEC
provider, that describes the original message. This data is
inserted in notifications and is transferred to the recipient,
along with the original message, inside a transport envelope.
Certification data include: date and time of dispatch, sender
email address, recipient(s) email address(es), subject, and
message ID.
Certified electronic mail: A service based on electronic mail,
as defined by the [SMTP] standard and its extensions, which
permits the transmission of documents produced with informatics
tools.
Complete delivery notification: A type of notification that
contains delivery confirmation text and certification data, as
well as the entire original message.
Concise delivery notification: A type of notification that
contains delivery confirmation text and certification data only
attached to it.
Delivery point: Is the point that delivers PEC messages to the
intended recipient's PEC mailbox. It also runs checks on the
source and correctness of the message. The messages it can emit
are:
o delivery notification.
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o non-delivery notification.
All messages received by the delivery point are stored in the
recipient's mailbox.
Delivery notification: Emitted by the receiver delivery point to
the sender incoming point, which then forwards it to the sender
delivery point, upon insertion of the message inside the
recipient's PEC mailbox. A separate delivery notification is
generated upon delivery of the message to each different
recipient indicated in the "To:" and "Cc:" fields of said
message. The notification is signed using the receiver PEC
provider's key.
Holder: The person to whom a PEC mailbox is assigned.
Incoming point: Is the point that receives messages within a PEC
domain. Once received, it runs checks on origin and correctness,
inserts messages that contain errors in anomaly envelopes,
checks for the presence of viruses in incoming messages, and,
when all checks go smoothly, forwards the received message to
the delivery point inside the same domain. The messages it can
emit are:
o take in charge notifications (inter-provider acknowledgment);
o virus detection notifications;
o non-delivery notifications due to timeout;
o non-delivery notifications due to virus detection.
All messages received by the reception point are forwarded to
the delivery point of the same domain.
Message sent: A PEC message is considered sent when the sender's
PEC provider, after several checks, accepts the email and
returns an acceptance notification to the sender.
Message received: A PEC message is considered received when it
is stored in the receiver's mailbox, after which the receiver
PEC provider returns a delivery notification to the sender.
Msgid: Is the message ID generated by the email client, as
defined in [EMAIL], before the message is submitted to the PEC
system.
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Non-acceptance notification: Emitted by the sender access point
to its user when it is impossible for it to accept the message.
The reason (either virus or formal exceptions detection) is
indicated within the notification text, which also explicitly
informs the user that the message will not be forwarded to the
receiver. The notification is signed using the sender PEC
provider's key.
Non-delivery notification: Emitted by the PEC provider to the
sender of the original message, when message delivery is not
possible, to indicate the anomaly. Non-delivery can be caused by
one of the following 3 reasons:
o timeout; notification is generated by the sender incoming
point and sent to the sender delivery point.
o virus detection; notification is generated by the receiver
incoming point and sent to the sender incoming point.
o other reasons; such as disk quota exceeded, domain unknown or
user unknown. In this case, the notification is generated by
the receiver incoming point to the sender incoming point.
Original message: Is the user-generated message before its
arrival to the sender access point. The original message is
delivered to the recipient inside a transport envelope.
PEC domain: Corresponds to a DNS domain dedicated to the
holders' mailboxes. Within a PEC domain, all PEC mailboxes MUST
belong to holders. PEC messages MUST be elaborated even if both
sender and recipient belong to the same PEC domain.
PEC mailbox: An electronic mailbox for which delivery
notifications are issued upon reception of PEC messages. Such a
mailbox can be defined exclusively within a PEC domain.
PEC msgid: Is a unique identifier generated by the PEC system,
which will substitute the msgid.
PEC provider: The entity that handles one or more PEC domains
with their relative points of access, reception, and delivery.
It is the holder of the key that is used for signing
notifications and envelope, and it interacts with other PEC
providers for interoperability with other holders.
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PEC provider's key: Is a key released by CNIPA to every PEC
provider. It is used to sign notifications and envelopes, and to
authorize access to the PEC providers directory.
PEC providers directory: Is an LDAP server positioned in an area
reachable by all PEC service providers. It constitutes the
technical structure related to the public list of PEC service
providers, and contains the list of PEC domains and service
providers with relevant certificates corresponding to the keys
used for signing notifications and transport envelopes.
Service mailbox: A mailbox for the sole use of the provider,
dedicated for the reception of take in charge and virus
detection notifications.
Take in charge notification: Emitted by the receiver incoming
point to the sender's service mailbox -through the latter's
incoming point- to attest that the receiver PEC provider has
taken responsibility for message delivery. Certification data is
inserted within this notification to allow its association with
the message it refers to. It is then signed using the receiving
PEC provider's key.
Time stamp: A digital evidence with which a temporal reference,
that can be opposed by third parties, is attributed to one or
more documents.
Transport envelope: A message created by the sender access
point, in which the original message and related certification
data are inserted. It is signed using the sender PEC provider's
key, and is delivered, unmodified, to the receiving PEC mailbox.
Thus, allowing the verification of the certification data by the
receiving user.
2. PEC model
2.1. System-generated messages
The PEC system generates messages in MIME format. They are
composed of a descriptive textual part and some other MIME
parts, the number and content of which varies according to the
type of message generated.
A system-generated message falls into one of the following
categories:
o Notifications;
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o Envelopes.
The message is inserted in an S/MIME v3 structure in CMS format
and signed with the PEC provider's private key. The X.509v3
certificate associated with the key MUST be included in the
aforementioned structure. The S/MIME format used to sign system-
generated messages is the "multipart/signed" format (.p7s), as
described in section 3.4.3 of [SMIMEV3].
To guarantee the verifiability of signatures on as many mail
clients as possible, X.509v3 certificates used by certified
email systems MUST abide by the profile found in section 6.5.
In order for the receiving mail client to be able to verify the
signature, the sender address must coincide with the one
indicated within the X.509v3 certificate. This mechanism
requires transport envelopes to indicate in the "From:" field a
sender address which is different from the one contained in the
original message. To allow for better message usability by the
receiving user, the sender's mail address in the original
message is inserted as a "display name". For example, a "From:"
field such as:
From: "John Smith" <john.smith@domain.com>
would result in the following "From:" value in the respective
transport envelope:
From: "On behalf of: john.smith@domain.com"
<certified-mail@provider.com>
It is necessary for the "Reply-To:" field to contain a correct
value in the transport envelope, so replies can be correctly
sent back to the proper destination. When such a field is not
explicitly specified in the original message, the system that
generates the transport envelope sees to its creation by
extracting the information from the "From:" field in the
original message. If on the other hand that field is specified
in the original message, it MUST NOT be altered.
When notifications need to be sent, the system uses as
destination address that of the original message's sender only,
exactly as is specified in the reverse path data of the SMTP
protocol. Notifications MUST be sent to the sender's PEC mailbox
without taking into account the "Reply-To:" field, which might
be present in the original message's header.
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All system-generated PEC messages are identifiable for having a
specific header defined in PEC according to the type of message
generated.
To determine the certification data, the elements used for the
actual routing of the message are employed. In SMTP dialog
phases, the reverse path and forward path data ("MAIL FROM" and
"RCPT TO" commands) are thus considered certification data of
both the sender and the recipients respectively. Addressing data
present in the message body ("To:" and "Cc:" fields) are used
solely in order to discriminate between primary and carbon copy
recipients when necessary; addressing data present in the "Bcc:"
field MUST be considered invalid by the system.
2.1.1. Message types
All system-generated messages inherit their header fields and
values from the original message, with extra fields added
according to the type of message generated.
2.1.1.1. Notifications
They have the purpose of informing the sending user and
interacting providers of the progress the message is making
within the PEC network.
2.1.1.1.1. Success notifications
Indicates an acknowledgment on the provider's side for the
reception or handling of a PEC message. More specifically, it
can indicate one of 3 situations: acceptance, take in charge, or
delivery.
Added header fields are:
o X-Ricevuta
o X-Riferimento-Message-ID
The field "X-Ricevuta" (Notification) indicates the type of
notification contained in the message, whereas "X-Riferimento-
Message-ID" (Reference Message-ID) contains the message ID
generated by the mail client.
The body contents differ according to the notification type.
This is described more thoroughly in chapter 3.
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o An acceptance notification informs the user that his provider
has accepted the message and will be taking care of passing
it on to the provider(s) of the addressee(s).
o A take in charge notification is an inter-provider
communication only, it MUST NOT concern the users. With this
notification, the receiving provider simply informs the
sending one that it has received a PEC message, and will take
the responsibility of forwarding it to the addressee(s). From
then on, the sender provider is no longer held responsible as
to the whereabouts of the message, but is limited to
notifying its user of the success or failure of delivery.
o Delivery notifications take place as the final communication
of a transaction, indicating overall success in handing the
message over to the addressee(s).
2.1.1.1.2. Delay notifications
Delay notifications are sent out 12 hours after a message has
been dispatched from the sending provider, and no take in charge
or delivery notification was received. These have the sole
purpose of notifying the user of the delay.
If another 12 hours go by without any sign of a take in charge
or delivery notification (amounting to a 24-hour delay), another
delay notification is dispatched to the user informing him of
the possible delivery failure. The provider will not keep track
of the delay any further.
2.1.1.1.3. Failure notifications
They are sent when there is some error in transmission or
reception. More specifically, a failure notification can
indicate either a formal-exception error, or a virus detection.
Added header fields are:
o X-Ricevuta;
o X-Riferimento-Message-ID;
o X-VerificaSicurezza [optional]
"X-Ricevuta" (Notification) and "X-Riferimento-Message-ID"
(Reference Message-ID) have the same roles as indicated in
section 2.1.1.1.1 (Success Notifications). "X-VerificaSicurezza"
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(Security Verification) is an optional header field, used for
virus-related notifications.
Body contents differ according to notification type. This is
described more thoroughly in chapter 3.
2.1.1.2. PEC envelopes
Messages entering the PEC network are inserted within specific
PEC messages, called envelopes, before they are allowed to
circulate further within the network. These envelopes MUST
inherit the following header fields, along with their unmodified
values, from the message itself.
o Received
o To
o Cc
o Return-Path
o Reply-to (if present)
Depending on the type of message requesting admission into the
PEC network, it will be inserted either in a "Transport
Envelope", or in a "Anomaly Envelope". Distinction will be
possible through the addition of the "X-Transport" header field.
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2.2. Basic structure
+-------------+ +------------+
| +--+ | | |
| |AP| | | |
+----+ | +--+ | messages& | +--+ +---+ | +----+
|user|<-->| |<------------->| |DP| |InP| |<-->|user|
+----+ | +--+ +---+ | notifications | +--+ +---+ | +----+
| |DP| |InP| | | |
| +--+ +---+ | | |
+-------------+ +------------+
PEC PEC
sender receiver
provider provider
where:
AP = Access Point
DP = Delivery Point
InP = Incoming Point
2.2.1. Access point
This is what the user client at the sender side interacts with,
giving the user access to PEC services set up by the provider.
Such access MUST be preceded by user authentication on the
system (see section 6.2). The access point is then to receive
the original messages its user wishes to send, run some formal
checks, and act according to the outcome:
o if the message passes all checks, the access point generates
an acceptance notification and inserts the original message
inside a transport envelope;
o if some formal exception is detected, the access point
refuses the message and emits the relevant non-acceptance
notification (see section 3.1.1);
o if a virus is detected, the access point generates a non-
acceptance notification and inserts the original message as
is in a special store.
Generation of the acceptance notification indicates to the user
that the message was accepted by the system, certifying also the
date and time of the event. The notification MUST contain user-
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readable text, and an XML part containing the certification
data. The notification MAY also contain other attachments for
extra features offered by the provider.
Using the data available in the PEC providers directory (see
section 4.5), the access point runs checks on every recipient in
the "To:" and "Cc:" fields present in the original message to
verify whether they belong to the PEC infrastructure or to non-
PEC domains. Such checks are done by verifying the existence,
through a case insensitive search, of the recipients' domains in
the "managedDomains" attribute found within the PEC providers
directory. Therefore, the acceptance notification (and relevant
certification data) relates, for each address, the typology of
its domain; PEC or non-PEC.
The identifier (from now on PEC msgid) of accepted original
messages within the PEC infrastructure MUST be unambiguous in
order to consent correct tracking of messages and relative
notifications. The format of such an identifier is:
[alphanumeric string]@[provider mail domain]
or:
[alphanumeric string]@[FQDN mail server]
Therefore, both the original message and the corresponding
transport envelope MUST contain the following header field:
Message-ID: <[unique identifier]>
In case the email client that is interacting with the access
point has already inserted a Message ID (from now on msgid) in
the original message, that msgid SHALL be substituted by a PEC
msgid. In order to allow the sender to link the message sent
with the relative notifications, the msgid MUST be inserted in
the original message as well as the relative notifications and
transport envelope. If existent, the msgid is REQUIRED to be
provided in the original message's header by adding the
following header field:
X-Riferimento-Message-ID: <[original Message ID]>
which will also be inserted in the transport envelope and
notifications, and related in the certification data (see
section 4.4).
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2.2.2. Incoming point
This point permits the exchange of PEC messages and
notifications between PEC providers. It is also the point
through which ordinary mail messages can be inserted within the
circuit of certified mail.
The exchange of messages between providers takes place through
SMTP-based transactions, as defined in [SMTP]. If SMTP
communication errors occur, they can be handled using the
standard error notification mechanisms, as provided by SMTP in
[SMTP] and [SMTP-DSN]. The same mechanism is also adapted for
handling transitory errors, that result in long idling periods,
during an SMTP transmission phase. In order to guarantee the
emission of a signal to the user when an error occurs,
coherently with the modalities defined in section 3.3.3, the
systems that handle PEC traffic MUST adopt a time limit for
message idleness equal to 24 hours.
Once a message arrives, the incoming point runs the following
list of checks and operations:
o verifies correctness and nature of the incoming message;
o if the incoming message is a correct and undamaged transport
message:
- emits a take in charge notification towards the sender
provider (section 3.2.1);
- forwards the transport envelope to the delivery point
(section 3.3).
o if the incoming message is a correct and undamaged
notification:
- forwards the notification to the delivery point.
o if the incoming message does not conform to the prerequisites
of a correct and undamaged transport envelope or
notification, but comes from a PEC provider, therefore passes
the verifications regarding existence, origin, and signature
validity, then the message MUST be propagated towards the
recipient. Therefore, the incoming point:
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- inserts the incoming message in an anomaly envelope
(section 3.2.2);
- forwards the anomaly envelope to the delivery point.
o if the incoming message does not originate from a PEC system,
therefore fails verifications regarding existence, origin and
signature validity, then the message will be treated as
ordinary email, and, if propagated to the recipient:
- is inserted in an anomaly envelope (section 3.2.2);
- the anomaly envelope is forwarded to the delivery point.
The take in charge notification is generated by the receiving
provider and sent to the sending provider. Its purpose is to
keep track of the message in its transition from one provider to
another, and is therefore strictly intra-provider communication;
the end user knows nothing about it.
To check the correctness and integrity of a transport envelope
or notification, the incoming point runs the following tests:
o Signature existence - the system verifies the presence of an
S/MIME signature structure within the incoming message;
o Signature origin - the system verifies whether or not the
signature was emitted by a PEC provider. So, the incoming
point extracts the certificate used for signing the incoming
message and verifies its presence in the PEC providers
directory. To facilitate the check, it is possible to
calculate the extracted certificate's SHA1 hash value and
perform a case-insensitive search of its hexadecimal
representation within the "providerCertificateHash" attribute
found in the PEC providers directory. This operation allows
to easily identify the sender provider for subsequent and
necessary matching checks between the extracted certificate
and the one present in the provider's record;
o Signature validity - S/MIME signature correctness is verified
by recalculating the signature algorithm and verifying the
CRL and temporal validity of the certificate. In case some
caching mechanism is used for CRL contents, an update
interval MUST be adopted so that the most up-to-date data is
guaranteed, thus minimizing the possible delay between a
publication revocation by the Certification Authority and the
variation acknowledgment by the provider;
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o Formal correctness - the provider performs sufficient and
necessary checks to guarantee formal correctness aspects
which are necessary for interoperability.
If a virus-infected transport envelope passes the checks just
mentioned it is still considered correct and undamaged. The
presence of the virus will be detected in a second phase, during
which the contents of the transport envelope are verified. Thus,
the incoming point will refrain from forwarding the message to
the recipient, instead sending the appropriate notification of
non-delivery and storing the virus-infected message in a special
storage.
In case ordinary mail messages are received, the PEC provider
SHALL perform virus checks in order to prevent the infiltration
of potentially dangerous mail messages within the PEC circuit.
If a virus is detected in an ordinary mail message, the latter
can be discarded at the incoming point before it enters the PEC
circuit. In other words, no special treatment is reserved for
the error, but a handling that is conformant to the procedures
usually followed for messages going through the Internet.
When a virus is detected inside a transport envelope during the
reception phase, the receiver's provider emits a virus detection
notification to the sender provider. The sender provider then
MUST:
o check what virus typologies were not detected by its own
antivirus, to understand the motivations and verify the
possibility of interventions;
o send a virus-induced non-delivery notification to the sender.
2.2.3. Delivery point
Is the point that receives messages from the incoming point and
forwards them to the final recipient.
It MUST run a series of tests on received messages before
forwarding them to the user. It first verifies the typology of
the message, and decides whether or not a notification should be
issued to the sender. The delivery notification (section 3.3.2)
is emitted after the message was delivered to the recipient's
PEC mailbox and only at reception of a valid transport envelope,
which can be identifiable by the presence of the header
attribute:
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X-Trasporto: posta-certificata
In all other cases, such as anomaly envelopes and notifications,
the delivery notification is not emitted. In any case, the
message received from the delivery point MUST be delivered
unmodified to the recipient's mailbox.
The delivery notification indicates to the sender that the
message sent was in fact conveyed to the specified recipient's
mailbox, and certifies the date and time of delivery through use
of user-readable text and an XML part containing certification
data, along with other possible attachments added for extra
features offered by the provider.
If the message received at the delivery point can't be delivered
to the destination mailbox, the delivery point emits a non-
delivery notification (section 3.3.3). This notification is
generated when an relative to the delivery of a correct
transport envelope is encountered.
2.2.4. Storage
Each provider MUST dedicate a special storage for the deposition
of any virus-infected messages encountered. Whether the virus be
detected by the sender's access point or the receiver's incoming
point, the provider that detects it MUST store the mail message
in its own storage, and keep it for 30 months.
2.2.5. Provider service mailbox
For exclusive use of the provider, dedicated to the reception of
notifications in 2 cases only:
o take in charge notifications; and
o virus detection notification.
2.3. Log
The server administrator MUST keep track of any and all
operations carried out in a specific message log file. The
information kept in the log for each operation is the following:
o message ID (the value present in the Message-ID header field
in the original message)
o date and time of event
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o sender of original message
o recipient(s) of original message
o subject of original message
o event type (reception, delivery, notification emission, etc)
o Message-IDs of related generated messages
o sending provider
The service provider MUST store that data and preserve it for 30
months.
3. Message processing
3.1. Access point
3.1.1. Formal checks on messages
When the access point receives a message the user wishes to
send, it MUST guarantee said message's formal conformity,
verifying that the:
o message body contains a "From:" field holding a [EMAIL]-
compliant email address;
o message body contains a "To:" field holding one or more
[EMAIL]-compliant email addresses;
o sender's address, specified in the SMTP reverse path,
coincides with the one in the message's "From:" field;
o recipients' addresses specified in the SMTP forward path
coincide with the ones present in the "To:" or "Cc:" fields
of the message;
o "Bcc:" field does not hold any value;
o total message size falls within the limits accepted by the
provider. Such limits apply depending on the number of
recipients as well; by multiplying it to the message size,
the outcome MUST fall within the limits accepted by the
provider. Italian Laws have specified this limit as being
30MB.
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If the message does not pass the tests, the access point MUST
NOT accept the message within the PEC system, thus emitting the
relative notification of non-acceptance.
3.1.2. Non-acceptance notification due to one or more formal
exceptions
When the access point cannot forward the message received, due
to failure in passing the formal checks, the sender is notified
of such an outcome. If the error is caused by the message
failing size checks, a non-acceptance notification is sent as
long as the size remains bound by a certain limit. If the size
exceeds said limit, error handling is left to SMTP.
The header for such a notification will contain the following
fields:
X-Ricevuta: non-accettazione
Date: [date of notification emission]
Subject: AVVISO DI NON ACCETTAZIONE: [original subject]
From: certified-mail@[mail domain]
To: [original sender]
X-Riferimento-Message-ID: [Message-ID of original message]
The body of this notification is composed of text that
constitutes the actual notification in readable format according
to a model that relates the following information:
Error in message acceptance
On [date] at [time] ([time zone]), in the message "[subject]"
originating from "[original sender]" and addressed to:
[recipient_1]
[recipient_2]
.
.
.
[recipient_n]
a problem was detected which prevents its acceptance due to
[error description].
The message was not accepted.
Message identification: [Message-ID]
The same certification information is inserted within an XML
file to be attached to the notification message, allowing its
automatic elaboration (section 4.4). Other attachments MAY BE
added to the notification message to follow certain functional
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specifications supplied by the provider, but the original
message MUST NOT in any case be inserted.
3.1.3. Non-acceptance notification due to virus detection
If the access point receives virus-infected emails from its
user, it MUST NOT accept them, but notify the sender immediately
of dispatch impossibility instead.
The access point MUST run some tests on the content of the
incoming message and reject it if a virus is detected. In which
case, a virus-detection-induced non-acceptance notification MUST
be emitted to clearly communicate the reason of message refusal
to the user.
For this non-acceptance notification the header contains the
following fields:
X-Ricevuta: non-accettazione
X-VerificaSicurezza: errore
Date: [notification emission date]
Subject: AVVISO DI NON ACCETTAZIONE PER VIRUS: [original
subject]
From: certified-mail@[mail_domain]
To: [original sender]
X-Riferimento-Message-ID: [Message-ID of original message]
The notification's body is composed of readable text according
to the following model:
Error in message acceptance due to virus presence
On [date] at [time] ([time zone]), in the message "[subject]"
originating from "[original sender]" and addressed to:
[recipient_1]
[recipient_2]
.
.
.
[recipient_n]
a security problem was detected [ID of detected content
type].
The message was not accepted.
Message identification: [Message-ID]
The same certification data is inserted in an XML file added to
the notification to allow for automatic elaboration (section
4.4). The notification MAY contain other attachments relevant to
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specific functionalities supplied by the provider, though the
original message MUST NOT in any case be attached.
3.1.4. Acceptance notification
The acceptance notification is a message sent to the sender,
containing date and time of acceptance, sender and recipient
data, and subject.
The header will contain the following fields:
X-Ricevuta: accettazione
Date: [actual date of acceptance]
Subject: ACCETTAZIONE: [original subject]
From: certified-mail@[mail_domain]
To: [original sender]
X-Riferimento-Message-ID: [Message-ID of original message]
The message body is composed of text that constitutes the
notification in readable format, according to a model that
relates the following information:
Acceptance notification
On [date] at [time] ([time zone]), the message "[subject]"
originating from "[original sender]" and addressed to:
[recipient_1] (["certified mail" | "ordinary mail"])
[recipient_2] (["certified mail" | "ordinary mail"])
.
.
.
[recipient_n] (["certified mail" | "ordinary mail"])
was accepted by the system and forwarded to the recipient(s).
Message identification: [Message-ID]
The same certification information is inserted within an XML
file attached to the notification message, allowing its
automatic elaboration (section 4.4). Other attachments MAY BE
added to the notification message to follow certain functional
specifications supplied by the provider.
3.1.5. Transport envelope
A transport envelope is a message generated by the access point
which contains the original message as well as certification
data.
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As was mentioned in section 2.1.1.2, the transport envelope
inherits from the original message the values of the following
header fields, which MUST be related unmodified:
o Received
o To
o Cc
o Return-Path
o Reply-To (if present)
On the other hand, the following fields will HAVE TO be
modified, or inserted if necessary:
X-Trasporto: posta-certificata
Date: [actual date of acceptance]
subject: POSTA CERTIFICATA: [original subject]
From: "On behalf of: [original sender]"
<certified-mail@[mail_domain]>
Reply-To: [original sender] (inserted only if not already
present)
Message-ID: [PEC message ID generated as explained in 2.2.1]
X-Riferimento-Message-ID: [message ID of original message]
X-TipoRicevuta: [completa/breve/sintetica]
The "X-TipoRicevuta" field indicates the type of delivery
notification the sender wishes to receive - complete, brief, or
concise.
The body of the transport envelope is composed of text that
constitutes the readable format of the message, according to a
model that relates the following certification data:
Certified mail message
On [date] at [time] ([time zone]), the message "[subject]"
was sent by "[original sender]" and addressed to:
[recipient_1]
[recipient_2]
.
.
.
[recipient_n]
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The original message is included in attachment.
Message identification: [Message-ID]
Within the transport envelope, the entire, non-modified original
message is attached in a [EMAIL]]compliant format (except for
what has been said regarding the Message ID). In the same
transport envelope, another part is added, which is an XML part.
It is easy to elaborate, and contains the certification data
that was already related in text format, as well as other
information on the type of message and type of notification
requested (section 4.4). Other elements MAY BE added to the
transport envelope for functionalities supplied by the PEC
provider.
Even if the "From:" field of the transport envelope is modified
to allow for the verification of the signature by the recipient,
routing data of the transport envelope (forward and reverse
paths) remain unchanged with respect to the same data of the
original message.
3.1.6. Timeout delivery error notification
If the sending provider does not receive a take in charge or
delivery notification from the receiving provider within 12
hours after message dispatch, it informs the user that the
recipient's provider might not be able to deliver the message.
In case the sending provider doesn't receive a delivery
notification within 24 hours after message dispatch, it emits
another non-delivery notification to the user by the 24-hour
timeout, but not before 22 hours have passed.
Such a communication takes place through a notification of non-
delivery due to timeout, the header of which contains the
following fields:
X-Ricevuta: preavviso-errore-consegna
Date: [date of notification emission]
Subject: AVVISO DI MANCATA CONSEGNA PER SUP. TEMPO MASSIMO:
[original subject]
From: certified-mail@[mail_domain]
To: [original recipient]
X-Riferimento-Message-ID: [Message-ID of original message]
The message body of the first non-delivery notification (12-hour
timeout) is composed of text that represents the readable format
of the notification, which will relate the following data:
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Non-delivery notification
On [date] at [time] ([time zone]), the message
"[subject]" originating from "[original sender]"
and addressed to "[recipient]"
has not been delivered within the first 12 hours following
its dispatch.
Not excluding that the message will eventually be delivered, it
is deemed useful to consider that dispatch might not have a
positive outcome. The system will see to sending another non-
delivery notification if in the following twelve hours no
confirmation is received from the recipient.
Message identification: [Message-ID]
On the other hand, 24-hour-timeout induced notifications, who
have the same header as described above, will have the following
text in their body:
Non-delivery notification
On [date] at [time] ([time zone]), the message
"[subject]" originating from "[original sender]"
and addressed to "[recipient]"
has not been delivered within 24 hours of its dispatch.
The transaction is deemed to be considered terminated with a
negative outcome.
Massage identification: [Message-ID]
The same certification data is inserted in an XML file to be
attached to both notification types to allow an automatic
elaboration (section 4.4). Within the notification other
attachments MAY be present for specific functionalities supplied
by the PEC provider; nonetheless the original message MUST NOT
in any case be included.
A timeout notification is generated if one of the following
scenarios occurs:
o the sending provider receives a take in charge notification
during the first 12 hours following message dispatch, but
does not receive a delivery notification at all. In this case
it would be a 24-hour timeout notification.
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o the sending provider does not receive a take in charge
notification, but receives a delivery notification after 12
hours and before the 24-hour timeout. In this case it would
be a 12-hour timeout notification.
o the sending provider doesn't receive neither a take in charge
notification nor a delivery notification. In this case 2
timeout notifications are generated; a 12-hour and a 24-hour
timeout notification.
3.2. Incoming point
3.2.1. Take in charge notification
When correct PEC transport envelopes (as defined in section
2.2.2.) are exchanged between PEC providers, the receiver MUST
dispatch a take in charge notification to the sender. The
dispatched take in charge notifications concern all recipients
to whom the incoming message was addressed, as stated in the
routing data (forward and reverse paths) of the SMTP
transaction. Within the certification data of a single take in
charge notification, all recipients of the message to which it
refers are listed. In general, when receiving a transport
envelope, each provider MUST emit one or more take in charge
notifications in order to cover, in absence of SMTP transport
errors, all the recipients in its jurisdiction.
The header of a take in charge notification contains the
following fields:
X-Ricevuta: presa-in-carico
Date: [date of take in charge]
Subject: PRESA IN CARICO: [original subject]
From: certified-mail@[mail_domain]
To: [sender provider service mailbox]
X-Riferimento-Message-ID: [Message-ID of original message]
The provider's service mail address is obtained from the PEC
providers directory during the necessary queries made in the
signature verification stage.
The notification body is constructed following the underlying
model:
Take in charge notification
On [date] at [time] ([time zone]), the message "[subject]"
originating from "[original sender]" and addressed to:
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[recipient_1] (["certified mail" | "ordinary mail"])
[recipient_2] (["certified mail" | "ordinary mail"])
.
.
.
[recipient_n] (["certified mail" | "ordinary mail"])
was accepted by the system.
Message identification: [Message-ID]
The same certification data is inserted in an XML file which is
added to the notification message to allow for automatic
elaboration (section 4.4). The notification MAY also contain
other attachments relevant to specific functionalities supplied
by the provider.
3.2.2. Anomaly envelope
If the tests on an incoming message detect an error, or the
message is identified as being ordinary mail and the provider is
set to forward it to the recipient, the system inserts such a
message in an anomaly envelope. Before delivery, the entire
message received at the incoming point is inserted in an
[EMAIL]-compliant format as an attachment inside a new message
that HAS TO inherit the values for the following header fields
unmodified from the message received:
o Received
o To
o Cc
o Return-Path
o Message-ID
Whereas, the following header fields will HAVE TO be modified or
inserted:
X-Trasporto: errore
Date: [message arrival date]
Subject: ANOMALIA MESSAGGIO: [original subject]
From: "On behalf of: [original sender]"
<certified-mail@[mail_domain]>
Reply-To: [original sender (inserted only if not already
present)]
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The body is composed of user-readable text according to a model
that relates the following data:
Message anomaly
On [date] at [time] ([time zone]), the message "[subject]"
originating from "[original sender]" and addressed to:
[recipient_1]
[recipient_2]
.
.
.
[recipient_n]
was received.
The data has not been certified due to the following error:
[concise description of error]
The original message is attached.
Due to uncertainty regarding origin and/or conformity of the
message received, the anomaly envelope MUST NOT contain
attachments other than the entire message that arrived at the
reception point.
Even though the "From:" field of the anomaly envelope is
modified for signature verification purposes, routing data of
such an envelope (forward and reverse paths) remain unchanged
with respect to the same data present in the message received.
Doing so guarantees both the forwarding of the message to the
recipients, and the reception of SMTP error notifications, if
any occur, by the sender (as specified in [SMTP] & [SMTP-DSN]).
3.2.3. Virus detection notification
If the incoming point receives virus-infected PEC messages, it
MUST NOT forward them, rather it MUST inform the sending
provider, which will in turn inform the sending user, of the
impossibility to go through with the transmission. A separate
notification of virus detection will HAVE to be sent on behalf
of every recipient within the provider's domain.
In case a virus is detected during the reception phase of a
message whose origin was asserted through sender signature
verification, the system generates a virus-detected
notification, indicating the error found, to be sent to the
sending provider's service mailbox.
For this kind of notification, the header contains the following
fields:
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X-Ricevuta: rilevazione-virus
X-Sender: [original sender]
Date: [date of notification emission]
subject: PROBLEMA DI SICUREZZA: [original subject]
From: certified-mail@[mail_domain]
To: [sender provider notifications]
X-Riferimento-Message-ID: [Message-ID of original message]
The body is composed of readable text according to a model which
relates the following data:
Virus detection notification
On [date] at [time] ([time zone]), in the message "[subject]"
originating from "[original sender]" and addressed to
"[recipient]" a security problem was detected [ID of content
type detected].
Message identification: [Message-ID]
The same certification data is inserted in an XML file and
attached to the notification to allow for automatic elaboration
(section 4.4). The notification MAY contain other attachments
relevant to specific functionalities supplied by the provider;
however, it MUST NOT contain the original message.
The message body MUST contain the reason for which the
transmission could not be completed.
3.2.4. Virus-induced delivery error notification
At the arrival of a virus detected notification from the
receiving provider, the sender provider emits a non-delivery
notification to the sending user.
The header for this notification contains the following fields:
X-Ricevuta: errore-consegna
X-VerificaSicurezza: errore
Date: [date of notification emission]
Subject: AVVISO DI MANCATA CONSEGNA PER VIRUS: [original
subject]
From: certified-mail@[mail_domain]
To: [original sender]
X-Riferimento-Message-ID: [Message-ID of original message]
The body is composed of readable text according to the following
data:
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Delivery error notification due to virus
On [date] at [time] ([time zone]), in the message "[subject]"
addressed to "[recipient]"
a security problem was detected [ID of content type detected
by the anti-virus].
The message was not delivered.
Message identification: [Message-ID]
All the information necessary for the construction of such a
notification can be obtained from the correlated virus-detected
notification.
The same certification data is inserted in an XML file and
attached to the notification message to allow for automatic
elaboration (section 4.4). The notification message MAY contain
other attachments relevant to specific functionalities supplied
by the provider. The reason for which the transaction was
impossible to complete MUST be specified within the message
body.
3.3. Delivery point
3.3.1. Checks on incoming messages
When a message arrives at the delivery point, the system
verifies its type and determines whether or not a notification
should be emitted to the sender.
3.3.2. Delivery notification
A delivery notification is issued after the received message has
been delivered to the recipient's mailbox, and only upon the
reception of a correct PEC transport envelope. The latter can be
easily identifiable for the presence of the following header
field:
X-Trasporto: posta-certificata
In all other cases (e.g. anomaly envelopes, notifications), the
delivery notification is not issued. In any case, the message
received at the delivery point MUST be delivered to the
recipient's mailbox unchanged.
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This notification tells the user that his/her message has been
successfully delivered to the specified recipient. It includes
readable text, that certifies the date and time of delivery,
sender and receiver data, and the subject. It also contains an
XML certification data file, and other optional attachments for
functionalities offered by the provider.
The following fields are inserted in the header:
X-Ricevuta: avvenuta-consegna
Date: [delivery date]
Subject: CONSEGNA: [original subject]
From: certified-mail@[mail_domain]
To: [original sender]
X-Riferimento-Message-ID: [Message-ID of original message]
The value of the "X-TipoRicevuta" header field in the transport
envelope is derived from the original message, thus allowing the
sender to determine the format of the delivery notifications
relative to the primary recipients of the original message.
3.3.2.1. Delivery notification: complete
This is the default value for delivery notifications. When no
value for the "X-TipoRicevuta" is specified, or when it contains
the value "complete", the system will require a complete
delivery notification from addressees in the "To:" field, while
a concise notification (section 3.3.2.3) will be required from
those in the "Cc:" field. The distinction between primary
recipients and those receiving in carbon copy is done through an
analysis of the "To:" and "Cc:" fields of the message with
respect to the delivery addressee. Exclusively in notifications
sent on behalf of primary recipients, along with the attachments
already described, a complete copy of the original message is
inserted. In case the system in charge of delivery is not able
to determine the recipient type due to ambiguity problems in the
"To:" and "Cc:" fields, delivery will HAVE TO be considered as
if addressed to a primary recipient and include the complete
copy of the original message.
The notification body is composed of readable text according to
a model that relates the following certification data:
Delivery notification
On [date] at [time] ([time zone]), the message "[subject]"
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originating from "[original sender]" and addressed to
"[recipient]" was placed in the destination's mailbox.
Message identification: [Message-ID]
The same certification data is inserted in an XML file to be
attached to the notification (section 4.4), along with any other
attachments that MAY be inserted for specific functionalities
supplied by the provider. The delivery notification MUST be
issued on the behalf of every recipient of the message.
3.3.2.2. Delivery notification: brief
In order to decrease the amount of data flowing, it is possible
for the sender to ask for a delivery notification in "brief"
format. The brief delivery notification contains the original
message, with all attachments, if present, substituted with
their respective ciphered hash values. To be able to verify the
transmitted contents, it is necessary for the sender to keep the
original copy of the attachment(s), to which the hash values
refer, unchanged.
If the transport envelope contains the header
X-TipoRicevuta: breve
the delivery point emits a brief delivery notification on behalf
of the primary recipients, and a concise one (section 3.3.2.3)
on behalf of carbon copy recipients. The value of the header in
the transport envelope is derived from the original message.
The notification body is composed of readable text according to
a model that relates the following certification data:
Brief delivery notification
On [date] at [time] ([time zone]), the message "[subject]"
originating from "[original sender]" and addressed to
"[recipient]"
was placed in the destination's mailbox.
Message identification: [Message-ID]
The same certification data is inserted in an XML file and
attached to the notification (section 4.4), along with other
optional attachments specific to provider-supplied
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functionalities. The delivery notification is issued on behalf
of every recipient of the message.
The MIME structure of the original message is unaltered as it is
attached to the notification, but its attachment(s) are
substituted with as many text files as the attachments are, each
containing the hash value of the file it substitutes. The
attachments are identified through the presence of the "name"
parameter in the header "content-type", or "filename" in the
header "content-disposition" of the MIME part.
When the original message has an S/MIME format, it is necessary
not to alter the integrity of the message structure, which would
result in modifying the MIME parts of the S/MIME construction.
Verification of the S/MIME nature in the original message takes
place when the MIME type of the top-level entity (which
coincides with the message itself) is checked. An S/MIME message
MAY have the following MIME types (as per [SMIMEV3]):
o multipart/signed
Represents an original message signed by the sender using the
structure described in [MIME-SECURE]. The message is made up of
2 MIME parts: the first is the message itself before the
application of the sender's signature, whereas the second
contains signature data. The second part (generally of type
"application/pkcs7-signature" or "application/x-pkcs-signature")
contains data added during the signing phase and MUST be left
unchanged to avoid compromising the overall message structure;
o "application/pkcs7-mime" or "application/x-pkcs7-signature"
The message is composed of a sole CMS object within the MIME
part. Given the impossibility to distinguish attachments, if
present within the CMS object, the MIME part is left intact
without being substituted by the respective hash value, thus
determining the emission of a brief delivery notification with
the same contents of a normal delivery notification.
If the original message contains attachments whose content-type
is "message/rfc822", i.e. contains an email message as
attachment, the entire attached message is substituted with its
corresponding hash value.
Therefore, when emitting a brief delivery notification, the
provider MUST:
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1. Identify and extract all the attachments from the first MIME
part of the multipart/signed S/MIME message;
2. calculate the hash values of all the files attached by the
sender to the original message;
3. substitute originals with their hash values.
In general, in the case of original messages in S/MIME format,
the copy of the message inserted within the brief delivery
notification will have the following characteristics:
o if the original message is signed, the S/MIME structure and
signature-relative data will remain unchanged. The message
will generate an error in a future signature integrity
verification phase following the substitution of attachments
with the corresponding hash values.
o if the original message contains the "application/pkcs7-mime"
or "application/x-pkcs7-mime" MIME type, attachments present
in the message will not be substituted by their hash values,
due to impossibility of identification within a CMS
structure. The content of the brief delivery notification
will coincide with that of a normal delivery notification.
The algorithm used for hash calculation is the [SHA1],
calculated on the entire content of the attachment. To allow
distinction between hash files and the files to which they
refer, the suffix ".hash" is added to the original filename. The
hash value is written in the file using a hexadecimal
representation as a single sequence of 40 characters. The MIME
type of these attachments is set to "text/plain" to highlight
their textual nature.
3.3.2.3. Delivery notification: concise
If the transport envelope contains the header
X-TipoRicevuta: sintetica
the delivery point emits, both to primary and carbon copy
recipients, a concise delivery notification that does not
contain the original message.
The message body of the notification is composed of readable
text according to a model that relates the following
certification data:
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Concise delivery notification
On [date] at [time] ([time zone]), the message "[subject]"
originating from "[original sender]" and addressed to
"[recipient]" was placed in the destination's mailbox.
Message identification: [Message-ID]
The same certification data is inserted within an XML file to be
attached to the notification (section 4.4), along with other
optional attachments specific to provider-supplied
functionalities. The notification is sent to each one of the
recipients to whom the message is delivered.
The concise delivery notification follows the same emission
rules as the delivery notification; attached to it is the XML
file which contains the certification data only, and not the
original message.
3.3.3. Non-delivery notification
If an error occurs during the delivery of a correct PEC
transport message, the system generates a notification for non-
delivery to be sent to the sender, with indication of the error.
The header will contain the following fields:
X-Ricevuta: errore-consegna
Date: [date of notification emission]
subject: AVVISO DI MANCATA CONSEGNA: [original subject]
From: certified-mail@[mail_domain]
To: [original sender]
X-Riferimento-Message-ID: [Message-ID of original message]
The notification body is composed of readable text according to
a model that relates the following data:
Non-delivery notification
On [date] at [time] ([time zone]), in the message
"[subject]" originating from "[original sender]" and
addressed to "[recipient]" an error was detected [error
summary].
The message was refused by the system.
Message identification: [Message-ID]
The same certification data is inserted within an XML files
added to the notification in order to allow for a an automatic
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elaboration (section 4.4). The notification MAY contain other
attachments for specific functionalities supplied by the PEC
provider.
4. Formats
4.1. Temporal reference
For all operations carried out during message, notification, and
log elaboration processes by the access, incoming and delivery
points, it is necessary to have an accurate temporal reference
available. All events (generation of notifications, transport
envelopes, logs, etc) that constitute the transaction of message
elaboration at the access, incoming, and delivery points MUST
employ a sole temporal value obtained from within the
transaction itself. Doing this renders the instant of message
elaboration unambiguous within logs, notifications, messages,
etc, generated by the server.
4.2. User date/time
Temporal indications supplied by the service in readable format
(text in notifications, transport envelopes, etc) are provided
with reference to the legal time at the moment of the operation.
The date employs the format, "dd/mm/yyyy", whereas the hour uses
the format, "hh:mm:ss", where "hh" is in 24hour format. The date
and time are followed by the time zone, i.e. the difference
(hours and minutes) between local time and UTC, inserted between
parentheses. Representation of such a value is in the "[+|-
]hhmm" format, where the first character indicates a positive or
negative difference.
4.3. Attachments
This section describes the characteristics of the various
components of messages and notifications generated by a PEC
system. If one of the message parts contains characters with
values outside of the interval 0-127 (7-bit ASCII), that part
will have to be adequately encoded so that 7-bit transportation
compatibility is guaranteed (e.g. quoted-printable, base64).
4.3.1. Message body
Character set: ISO-8859-1 (Latin-1)
MIME type: text/plain or multipart/alternative
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The multipart/alternative MIME type MAY be used to add an HTML
version of the body of messages generated by the system. In this
case, two sub-parts MUST be present: one of type text/plain, the
other text/html. The HTML part will HAVE TO respect the
following conditions:
o it MUST contain the same information as related in the text
part;
o it MUST NOT contain references to elements (e.g. images,
sounds, font, style sheets) neither internal to the message
(added MIME parts) nor external (e.g. hosted on the
provider's server);
o MUST NOT have active content (e.g. JavaScript, VBscript,
Plug-in, ActiveX).
4.3.2. Original message
MIME type: message/rfc822
Attachment name: certmail.eml
4.3.3. Certification data
Character set: UTF-8
MIME type: application/xml
Attachment name: certdata.xml
4.4. Certification data scheme
Following is the DTD relative to the XML file that contains
certification data attached to the notifications.
<?xml version="1.0" encoding="UTF-8"?>
<!--Use the element "postacert" as root-->
<!--"tipo" indicates the typology of the PEC message-->
<!--The attribute "errore" can have the following values-->
<!--"nessuno" = no error-->
<!--"no-dest" (with type="errore-consegna") = -->
<!-- wrong recipient-->
<!--"no-dominio" (with type="errore-consegna") = -->
<!-- wrong domain-->
<!--"virus" (with type="errore-consegna") = virus-->
<!--"virus" (with type="non-accettazione") = virus-->
<!--"altro" = generic error-->
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<!ELEMENT postacert (intestazione, dati)>
<!ATTLIST postacert
tipo (accettazione |
non-accettazione |
presa-in-carico |
avvenuta-consegna |
posta-certificata |
errore-consegna |
preavviso-errore-consegna |
rilevazione-virus) #REQUIRED
errore (nessuno |
no-dest |
no-dominio |
virus |
altro) "nessuno">
<!--Header of the original message-->
<!ELEMENT intestazione (mittente,
destinatari+,
risposte,
oggetto?)>
<!--Sender ("From" field) of the original message-->
<!ELEMENT mittente (#PCDATA)>
<!--Complete list of recipients ("To" and "Cc" fields)-->
<!--of the original message-->
<!--"tipo" indicates the typology of the recipient-->
<!ELEMENT destinatari (#PCDATA)>
<!ATTLIST destinatari
tipo (certificato | esterno) "certificato">
<!--Value of the "Reply-To" field of the original message-->
<!ELEMENT risposte (#PCDATA)>
<!--Value of the "Subject" field of the original message-->
<!ELEMENT oggetto (#PCDATA)>
<!--PEC message data-->
<!ELEMENT dati (gestore-emittente,
data,
identificativo,
msgid?,
ricevuta?,
consegna?,
ricezione*,
errore-esteso?)>
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<!--Descriptive string of the provider that certifies -->
<!--the data-->
<!ELEMENT gestore-emittente (#PCDATA)>
<!--Date/time of message elaboration-->
<!--"zona" is the difference between local time and UTC in -->
<!--"[+|-]hhmm" format-->
<!ELEMENT data (giorno, ora)>
<!ATTLIST data zona CDATA #REQUIRED>
<!--Day in "dd/mm/yyyy" format-->
<!ELEMENT giorno (#PCDATA)>
<!--Local hour in "hh:mm:ss" format-->
<!ELEMENT ora (#PCDATA)>
<!--PEC msgid-->
<!ELEMENT identificativo (#PCDATA)>
<!--msgid of the original message before modifications-->
<!ELEMENT msgid (#PCDATA)>
<!--For transport envelopes and delivery notifications-->
<!--indicate the type of notification requested by the-->
<!-sender-->
<!ELEMENT ricevuta EMPTY>
<!ATTLIST ricevuta
tipo (completa |
breve |
sintetica) #REQUIRED>
<!--For delivery, non-delivery, virus-induced non-delivery, -->
<!-- virus detection, and timeout notifications-->
<!--Recipient address to which delivery has been carried -->
<!--out/tried-->
<!ELEMENT consegna (#PCDATA)>
<!--For take in charge notifications-->
<!--recipients for whom it is the relative notification-->
<!ELEMENT ricezione (#PCDATA)>
<!--In case of error-->
<!--brief description of the error-->
<!ELEMENT errore-esteso (#PCDATA)>
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4.5. PEC providers directory scheme
The PEC providers directory is created through a centralized
LDAP server that contains providers' data and their
corresponding PEC mail domains. The directory's base root is
"o=certmail", and the "DistinguishedName" of single records are
of the type, "providerName=<name>, o=certmail". Search within
the directory is carried out mainly in case-sensitive mode using
the "providerCertificateHash" attributes (during envelope
signature verification phase) or "managedDomains" (during
message acceptance phase). It is possible for the record of a
single provider to contain multiple "providerCertificate", and
the corresponding "providerCertificateHash", attributes in order
to allow the handling of the renewal of expiring certificates.
The provider MUST make sure to update its own record
sufficiently beforehand with respect to the expiration date of
the certificate, by adding a new certificate whose validity
overlaps with that of the previous one. The "LDIFLocationURL"
attribute MUST point to an HTTPS object supplied by the
provider, and containing an LDIF file according to [LDIF]. To
guarantee authenticity, the file MUST be signed by the provider
for the operations regarding its PEC services. The LDIF file,
the signature, and the X.509v3 certificate MUST be inserted in a
PKCS#7 structure in binary ASN.1 DER format as a file with
".p7m" extension. The centralized LDAP system downloads such a
file on a daily basis, and, after opportune verifications of the
appended signature, it applies it to the record relative to the
provider. The LDIF file that encompasses the data of all the PEC
providers is available, signed using the method described for
single providers as an HTTPS object, and can be found at the URL
to which the "LDIFLocationURL" attribute in the "dn: o=certmail"
record points. Through the LDIF file, single providers HAVE TO
keep a local copy of the directory, updated on a daily basis, in
order to improve system performance by avoiding continuous
request dispatches to the central system for every message
elaboration phase.
It is possible for the provider to define several distinct
records to indicate different secondary, administered operating
environments. Every record refers to a single secondary
operating environment for which it is possible to declare
specific attributes, and if need be distinct from those relative
to other environments and to the main environment. All records
MUST contain the name of the provider in the "providerName"
attribute, whereas the "providerUnit" attribute is used to
identify the secondary operating environments. The
"DistinguishedName" of the records relative to the secondary
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operating environments are of the type
"providerUnit=<environment>,providerName=<name>,o=certmail".
Every provider MUST have a record associated to its own main
environment, distinguishable for the absence of the
"providerUnit" attribute within the record and the
DistinguishedName. Records for secondary environments MUST
contain the "LDIFLocationURL" attribute, which is obtained from
the main environment's attribute for all records connected to
the provider. If secondary environments are present, the LDIF
found in the main environment's record MUST hold the contents of
all the provider-relevant records.
Following are the attributes defined for the scheme of the PEC
providers directory:
- providerCertificateHash: IA5 string
Hexadecimal representation of the hash in SHA1 format of the
X.509v3 certificate used by the provider for notifications and
PEC envelope signatures.
- providerCertificate: Certificate Binary transfer
Certificate(s) used by the provider for signing notifications
and transport envelopes.
- providerName: Directory string Single value
Name of PEC provider.
- mailReceipt: IA5 string Single value
Email address to which take in charge notifications and virus
detection notifications are sent.
- managedDomains: IA5 string
PEC domains handled by the provider.
- LDIFLocationURL: Directory string Single value
HTTPS URL where the definition of the record related to the
provider is maintained in LDIF format. When the attribute is
present in the record "dn: o=postacert", then it contains the
definition of the entire directory in LDIF format.
- providerUnit: Directory string Single value
Name of the secondary operating environment (not available for
the principal environment)
Next is the LDAP scheme for the PEC providers directory
according to the syntax described in [LDAP]:
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attributetype ( 16572.2.2.1
NAME 'providerCertificateHash'
DESC 'Hash SHA1 of X.509 certificate in hexadecimal
format'
EQUALITY caseIgnoreIA5Match
SYNTAX 1.3.6.1.4.1.1466.115.121.1.26{40} )
attributetype ( 16572.2.2.2
NAME 'providerCertificate'
DESC 'X.509 certificate in ASN.1 DER binary format'
SYNTAX 1.3.6.1.4.1.1466.115.121.1.8 )
attributetype ( 16572.2.2.3
NAME 'providerName'
DESC 'PEC provider'
EQUALITY caseIgnoreMatch
SUBSTR caseIgnoreSubstringsMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.15{32768}
SINGLE-VALUE )
attributetype ( 16572.2.2.4
NAME 'mailReceipt'
DESC 'E-mail address of the service mailbox'
EQUALITY caseIgnoreIA5Match
SUBSTR caseIgnoreIA5SubstringsMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.26{256}
SINGLE-VALUE )
attributetype ( 16572.2.2.5
NAME 'managedDomains'
DESC 'Domains handled by the PEC provider'
EQUALITY caseIgnoreIA5Match
SUBSTR caseIgnoreIA5SubstringsMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )
attributetype ( 16572.2.2.6
NAME 'LDIFLocationURL'
DESC 'URL of the LDIF file that defines the entry'
EQUALITY caseExactMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.15
SINGLE-VALUE )
attributetype ( 16572.2.2.7
NAME 'providerUnit'
DESC 'Name of the secondary operative environment'
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EQUALITY caseIgnoreMatch
SUBSTR caseIgnoreSubstringsMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.15{32768}
SINGLE-VALUE )
objectclass ( 16572.2.1.1
NAME 'LDIFLocationURLObject'
DESC 'Class for the insertion of a LDIFLocationURL
attribute'
MAY ( LDIFLocationURL )
SUP top AUXILIARY )
objectclass ( 16572.2.1.2
NAME 'provider'
DESC 'PEC provider'
SUP top
MUST ( providerCertificateHash $
providerCertificate $
providerName $
mailReceipt $
managedDomains)
MAY ( description $
LDIFLocationURL $
providerUnit) )
The following LDIF file represents an example of a providers'
directory, containing a base root and 2 fictitious providers.
The inserted certificates are two self-signed certificates used
for example purposes only:
dn: o=postacert
objectclass: top
objectclass: organization
objectClass: LDIFLocationURLObject
o: postacert
LDIFLocationURL: https://igpec.rupa.it/igpec.ldif.p7m
description: Base root for the PEC providers directory
dn: providerName=Anonymous Certified Mail S.p.A.,o=postacert
objectclass: top
objectclass: provider
providerName: Anonymous Certified Mail S.p.A.
providerCertificateHash:
7E7AEF1059AE0F454F2643A95F69EC3556009239
providerCertificate;binary::
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MIIDBjCCAm+gAwIBAgIBADANBgkqhkiG9w0BAQQFADBmMQswCQYDVQQGEw
JJVDEpMCcGA1UEChMgQW5vbmltYSBQb3N0YSBDZXJ0aWZpY2F0YSBTLnAu
QS4xLDAqBgkqhkiG9w0BCQEWHXBvc3RhLWNlcnRpZmljYXRhQGFucG9jZX
J0Lml0MB4XDTAyMTIwOTE3MjQxNVoXDTAzMTIwOTE3MjQxNVowZjELMAkG
A1UEBhMCSVQxKTAnBgNVBAoTIEFub25pbWEgUG9zdGEgQ2VydGlmaWNhdG
EgUy5wLkEuMSwwKgYJKoZIhvcNAQkBFh1wb3N0YS1jZXJ0aWZpY2F0YUBh
bnBvY2VydC5pdDCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkCgYEAr8J+qK
KdxV9LzDMPqwnEy0P8H/KwbI0Szs8p6UZajZdpeUK0Ncbrv1QyXZNNtSMC
2uL09HDyx8agjgZWdhypnehguiSK3busha15RSpMGhiqxmz2b0HhOG73Gf
alZelqrwqmElna4MNUaLhbOvTd/sqPUS378w5IaIhWxzy34XcCAwEAAaOB
wzCBwDAdBgNVHQ4EFgQUN8lC0znQWEs0xspZ/aBzsaGvRZMwgZAGA1UdIw
SBiDCBhYAUN8lC0znQWEs0xspZ/aBzsaGvRZOhaqRoMGYxCzAJBgNVBAYT
AklUMSkwJwYDVQQKEyBBbm9uaW1hIFBvc3RhIENlcnRpZmljYXRhIFMucC
5BLjEsMCoGCSqGSIb3DQEJARYdcG9zdGEtY2VydGlmaWNhdGFAYW5wb2Nl
cnQuaXSCAQAwDAYDVR0TBAUwAwEB/zANBgkqhkiG9w0BAQQFAAOBgQA58B
Z+q1qSKpuffzTBpMtbeFkDIxMqMa+ycnxdMNvcWgCm1A9ZiFJsvqYhDDqA
XxfHjkrzXuSZkYq6WiQCsLp0aYVy40QCIwbOunhrvsxh3vsG5CgN76JzZ9
5Z/1OCFNhLfqf1VH2NSS8TaYCCi/VO7W1Q1KkcA2VlxlQP7McSUw==
mailReceipt: ricevute@anpocert.it
LDIFLocationURL: https://www.anpocert.it/LDIF/anpocert.ldif.p7m
managedDomains: mail.anpocert.it
managedDomains: cert.company.it
managedDomains: costmec.it
description: Certified mail services for companies
dn: providerName=Postal Services S.p.A,o=postacert
objectclass: top
objectclass: provider
providerName: Postal Services S.p.A
providerCertificateHash:
e00fdd9d88be0e2cc766b893315caf93d5701a6a
providerCertificate;binary::
MIIDHjCCAoegAwIBAgIBADANBgkqhkiG9w0BAQQFADBuMQswCQYDVQQGEw
JJVDEfMB0GA1UEChMWU2Vydml6aSBQb3N0YWxpIFMuci5sLjEPMA0GA1UE
CxMGRC5DLkMuMS0wKwYJKoZIhvcNAQkBFh5wb3N0YS1jZXJ0aWZpY2F0YU
BzZXJwb3N0YWwuaXQwHhcNMDIxMjA5MTczMjE2WhcNMDMxMjA5MTczMjE2
WjBuMQswCQYDVQQGEwJJVDEfMB0GA1UEChMWU2Vydml6aSBQb3N0YWxpIF
Muci5sLjEPMA0GA1UECxMGRC5DLkMuMS0wKwYJKoZIhvcNAQkBFh5wb3N0
YS1jZXJ0aWZpY2F0YUBzZXJwb3N0YWwuaXQwgZ8wDQYJKoZIhvcNAQEBBQ
ADgY0AMIGJAoGBAKoc7n6zA+sO8NATMcfJ+U2aoDEsrj/cObG3QAN6Sr+l
ygWxYXLBZNfSDWqL1K4edLr4gCZIDFsq0PIEaYZhYRGjhbcuJ9H/ZdtWdX
xcwEWN4mwFzlsASogsh5JeqS8db3A1JWkvhO9EUfaCYk8YMAkXYdCtLD9s
9tCYZeTE2ut9AgMBAAGjgcswgcgwHQYDVR0OBBYEFHPw7VJIoIM3VYhuHa
eAwpPF5leMMIGYBgNVHSMEgZAwgY2AFHPw7VJIoIM3VYhuHaeAwpPF5leM
oXKkcDBuMQswCQYDVQQGEwJJVDEfMB0GA1UEChMWU2Vydml6aSBQb3N0YW
xpIFMuci5sLjEPMA0GA1UECxMGRC5DLkMuMS0wKwYJKoZIhvcNAQkBFh5w
b3N0YS1jZXJ0aWZpY2F0YUBzZXJwb3N0YWwuaXSCAQAwDAYDVR0TBAUwAw
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EB/zANBgkqhkiG9w0BAQQFAAOBgQApqeXvmOyEjwhMrXezPAXELMZwv4qq
r5ri4XuxTq6sS9jRsEbZrS+NmbcJ7S7eFwNQMNxYFVJqdWoLh8qExsTLXn
sKycSnHbCfuphrKvXjQvR2da75U4zGSkroiyvJ2s9TtiCcT3lQtIjmvrFb
aSBiyzj+za7foFUCQmxCLtDaA==
mailReceipt: takecharge@postalser.it
LDIFLocationURL: https://services.postalser.it/ldif.txt.p7m
managedDomains: postal-services.it
managedDomains: receivedmail.it
description: Certified mail services for the public
The following LDIF file represents an example of a PEC
providers' directory, containing a base root and 2 fictitious
providers, the first of which handles a secondary environment as
well. The certificates inserted are 2 self-signed certificates
used for example purposes only:
dn: o=postacert
objectclass: top
objectclass: organization
objectClass: LDIFLocationURLObject
o: postacert
LDIFLocationURL: https://igpec.rupa.it/igpec.ldif.p7m
description: Base root for the PEC providers directory
dn: providerName=Anonymous Certified Mail S.p.A.,o=postacert
objectclass: top
objectclass: provider
providerName: Anonymous Certified Mail S.p.A.
providerCertificateHash:
7E7AEF1059AE0F454F2643A95F69EC3556009239
providerCertificate;binary::
MIIDBjCCAm+gAwIBAgIBADANBgkqhkiG9w0BAQQFADBmMQswCQYDVQQGEw
JJVDEpMCcGA1UEChMgQW5vbmltYSBQb3N0YSBDZXJ0aWZpY2F0YSBTLnAu
QS4xLDAqBgkqhkiG9w0BCQEWHXBvc3RhLWNlcnRpZmljYXRhQGFucG9jZX
J0Lml0MB4XDTAyMTIwOTE3MjQxNVoXDTAzMTIwOTE3MjQxNVowZjELMAkG
A1UEBhMCSVQxKTAnBgNVBAoTIEFub25pbWEgUG9zdGEgQ2VydGlmaWNhdG
EgUy5wLkEuMSwwKgYJKoZIhvcNAQkBFh1wb3N0YS1jZXJ0aWZpY2F0YUBh
bnBvY2VydC5pdDCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkCgYEAr8J+qK
KdxV9LzDMPqwnEy0P8H/KwbI0Szs8p6UZajZdpeUK0Ncbrv1QyXZNNtSMC
2uL09HDyx8agjgZWdhypnehguiSK3busha15RSpMGhiqxmz2b0HhOG73Gf
alZelqrwqmElna4MNUaLhbOvTd/sqPUS378w5IaIhWxzy34XcCAwEAAaOB
wzCBwDAdBgNVHQ4EFgQUN8lC0znQWEs0xspZ/aBzsaGvRZMwgZAGA1UdIw
SBiDCBhYAUN8lC0znQWEs0xspZ/aBzsaGvRZOhaqRoMGYxCzAJBgNVBAYT
AklUMSkwJwYDVQQKEyBBbm9uaW1hIFBvc3RhIENlcnRpZmljYXRhIFMucC
5BLjEsMCoGCSqGSIb3DQEJARYdcG9zdGEtY2VydGlmaWNhdGFAYW5wb2Nl
cnQuaXSCAQAwDAYDVR0TBAUwAwEB/zANBgkqhkiG9w0BAQQFAAOBgQA58B
Z+q1qSKpuffzTBpMtbeFkDIxMqMa+ycnxdMNvcWgCm1A9ZiFJsvqYhDDqA
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XxfHjkrzXuSZkYq6WiQCsLp0aYVy40QCIwbOunhrvsxh3vsG5CgN76JzZ9
5Z/1OCFNhLfqf1VH2NSS8TaYCCi/VO7W1Q1KkcA2VlxlQP7McSUw==
mailReceipt: notifications@anpocert.it
LDIFLocationURL: http://www.anpocert.it/LDIF/anpocert.ldif.p7m
managedDomains: mail.anpocert.it
managedDomains: cert.company.it
managedDomains: costmec.it
description: Certified mail services for companies
dn: providerUnit=Secondary Environment, providerName=Anonymous
Certified Mail S.p.A.,o=postacert
objectclass: top
objectclass: provider
providerName: Certified Mail S.p.A.
providerUnit: Secondary Environment
providerCertificateHash:
7E7AEF1059AE0F454F2643A95F69EC3556009239
providerCertificate;binary::
MIIDBjCCAm+gAwIBAgIBADANBgkqhkiG9w0BAQQFADBmMQswCQYDVQQGEw
JJVDEpMCcGA1UEChMgQW5vbmltYSBQb3N0YSBDZXJ0aWZpY2F0YSBTLnAu
QS4xLDAqBgkqhkiG9w0BCQEWHXBvc3RhLWNlcnRpZmljYXRhQGFucG9jZX
J0Lml0MB4XDTAyMTIwOTE3MjQxNVoXDTAzMTIwOTE3MjQxNVowZjELMAkG
A1UEBhMCSVQxKTAnBgNVBAoTIEFub25pbWEgUG9zdGEgQ2VydGlmaWNhdG
EgUy5wLkEuMSwwKgYJKoZIhvcNAQkBFh1wb3N0YS1jZXJ0aWZpY2F0YUBh
bnBvY2VydC5pdDCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkCgYEAr8J+qK
KdxV9LzDMPqwnEy0P8H/KwbI0Szs8p6UZajZdpeUK0Ncbrv1QyXZNNtSMC
2uL09HDyx8agjgZWdhypnehguiSK3busha15RSpMGhiqxmz2b0HhOG73Gf
alZelqrwqmElna4MNUaLhbOvTd/sqPUS378w5IaIhWxzy34XcCAwEAAaOB
wzCBwDAdBgNVHQ4EFgQUN8lC0znQWEs0xspZ/aBzsaGvRZMwgZAGA1UdIw
SBiDCBhYAUN8lC0znQWEs0xspZ/aBzsaGvRZOhaqRoMGYxCzAJBgNVBAYT
AklUMSkwJwYDVQQKEyBBbm9uaW1hIFBvc3RhIENlcnRpZmljYXRhIFMucC
5BLjEsMCoGCSqGSIb3DQEJARYdcG9zdGEtY2VydGlmaWNhdGFAYW5wb2Nl
cnQuaXSCAQAwDAYDVR0TBAUwAwEB/zANBgkqhkiG9w0BAQQFAAOBgQA58B
Z+q1qSKpuffzTBpMtbeFkDIxMqMa+ycnxdMNvcWgCm1A9ZiFJsvqYhDDqA
XxfHjkrzXuSZkYq6WiQCsLp0aYVy40QCIwbOunhrvsxh3vsG5CgN76JzZ9
5Z/1OCFNhLfqf1VH2NSS8TaYCCi/VO7W1Q1KkcA2VlxlQP7McSUw==
mailReceipt: notifications@secondary.anpocert.it
managedDomains: management.anpocert.it
managedDomains: personnel.anpocert.it
description: Corporate internal services
dn: providerName=Postal Services S.r.l.,o=postacert
objectclass: top
objectclass: provider
providerName: Postal Services S.r.l.
providerCertificateHash:
e00fdd9d88be0e2cc766b893315caf93d5701a6a
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providerCertificate;binary::
MIIDHjCCAoegAwIBAgIBADANBgkqhkiG9w0BAQQFADBuMQswCQYDVQQGEw
JJVDEfMB0GA1UEChMWU2Vydml6aSBQb3N0YWxpIFMuci5sLjEPMA0GA1UE
CxMGRC5DLkMuMS0wKwYJKoZIhvcNAQkBFh5wb3N0YS1jZXJ0aWZpY2F0YU
BzZXJwb3N0YWwuaXQwHhcNMDIxMjA5MTczMjE2WhcNMDMxMjA5MTczMjE2
WjBuMQswCQYDVQQGEwJJVDEfMB0GA1UEChMWU2Vydml6aSBQb3N0YWxpIF
Muci5sLjEPMA0GA1UECxMGRC5DLkMuMS0wKwYJKoZIhvcNAQkBFh5wb3N0
YS1jZXJ0aWZpY2F0YUBzZXJwb3N0YWwuaXQwgZ8wDQYJKoZIhvcNAQEBBQ
ADgY0AMIGJAoGBAKoc7n6zA+sO8NATMcfJ+U2aoDEsrj/cObG3QAN6Sr+l
ygWxYXLBZNfSDWqL1K4edLr4gCZIDFsq0PIEaYZhYRGjhbcuJ9H/ZdtWdX
xcwEWN4mwFzlsASogsh5JeqS8db3A1JWkvhO9EUfaCYk8YMAkXYdCtLD9s
9tCYZeTE2ut9AgMBAAGjgcswgcgwHQYDVR0OBBYEFHPw7VJIoIM3VYhuHa
eAwpPF5leMMIGYBgNVHSMEgZAwgY2AFHPw7VJIoIM3VYhuHaeAwpPF5leM
oXKkcDBuMQswCQYDVQQGEwJJVDEfMB0GA1UEChMWU2Vydml6aSBQb3N0YW
xpIFMuci5sLjEPMA0GA1UECxMGRC5DLkMuMS0wKwYJKoZIhvcNAQkBFh5w
b3N0YS1jZXJ0aWZpY2F0YUBzZXJwb3N0YWwuaXSCAQAwDAYDVR0TBAUwAw
EB/zANBgkqhkiG9w0BAQQFAAOBgQApqeXvmOyEjwhMrXezPAXELMZwv4qq
r5ri4XuxTq6sS9jRsEbZrS+NmbcJ7S7eFwNQMNxYFVJqdWoLh8qExsTLXn
sKycPSnHbCfuphrKvXjQvR2da75U4zGSkroiyvJ2s9TtiCcT3lQtIjmvrF
baSBiyzj+za7foFUCQmxCLtDaA==
mailReceipt: takecharge@postalser.it
LDIFLocationURL: http://services.postalser.it/ldif.txt.p7m
managedDomains: postal-services.it
managedDomains: receivedmail.it
description: Certified mail services for the public
5. Example: Complete transaction between 2 PEC domains
A correct transaction between 2 PEC domains goes through the
following steps:
o The sending user sends an email to his provider's Access
Point;
o The Access Point runs all checks and emits an acceptance
notification to the user;
o The Access Point creates a transport envelope and forwards it
to the Incoming Point of the receiving provider;
o The receiver's Incoming Point verifies the transport envelope
and creates a take in charge notification to be sent to the
sending provider;
o The sender's Incoming Point verifies the validity of the take
in charge notification and forwards it to the Delivery Point;
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o The sender's Delivery Point saves the take in charge
notification in the provider's service mailbox;
o The receiver's Incoming Point forwards the transport envelope
to the receiver's Delivery Point;
o The receiver's Delivery Point verifies the contents of the
transport envelope and saves it in the recipient's mailbox;
o The receiver's Delivery Point creates a delivery notification
and sends it to the sender's Incoming Point;
o The sender's Incoming Point verifies the validity of the
delivery notification and forwards it to the sender's
Delivery Point;
o The sender's Delivery Point saves the delivery notification
in the sending user's mailbox;
o The receiving user has the message at his disposition.
6. Security-related aspects
6.1. Digital signature
The private key and signature operations MUST be handled using a
dedicated hardware security module (FIPS 140-2) which is able to
guarantee their security in compliance with the criteria adopted
in the European or international setting.
6.2. Authentication
User access to PEC services through the access point MUST be
allowed upon authentication on the system by the user himself.
For example, authentication modalities might use user-ID and
password, or, if available and considered necessary for the type
of service provided, the electronic ID card or the national
services card. Choice of authentication modality is left to the
better judgment of the service provider. Authentication is
necessary to guarantee, as much as possible, that the message is
sent by a PEC user, whose identification data is congruent with
the specified sender, so as to avoid falsification of the
latter.
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6.3. Secure interaction
In order to guarantee that the original message doesn't change
during the interaction, envelopment of and signature application
on outgoing messages is done at the access point, and the
subsequent verification of incoming messages is done at the
incoming point. The original message is inserted as attachment
within a transport envelope. The transport envelope signed by
the sending provider permits to verify that the original message
hasn't been modified during its transition from sender domain to
receiver domain.
All communications within the PEC network MUST use secure
channels, and integrity and confidentiality of the connections
between the PEC provider and the user MUST be guaranteed through
the use of secure protocols, such as those based on TLS and
those that create a secure transport channel on which non-secure
protocols are conveyed (e.g. IPSec).
The interaction between providers MUST take place using SMTP on
TLS, as per [SMTP-TLS]. The incoming point MUST provide and
announce its support for the STARTTLS extension, as well as
accept both unencrypted connections (for ordinary mail) and
protected ones.
To guarantee complete traceability in the flow of PEC messages,
these MUST NOT transit on systems external to the PEC circuit.
When exchanging messages between different providers, all
transactions MUST take place between machines that belong to the
PEC circuit, or those directly managed by the provider.
Secondary PEC messages reception systems, if present, MUST be
under direct control of the provider. An "MX" type record MUST
be associated to each PEC domain, defined within the system for
name resolution.
6.4. Virus
Another important security aspect, that concerns the entire PEC
system, is related to the technical and functional architecture
which MUST block the presence of viruses from endangering the
security of all handled messages; it is therefore REQUIRED to
have installations and continuous updates of anti-virus systems
that hinder infections as much as possible, without intervening
on the content of the certified mail, in compliance with what
has been discussed thus far.
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6.5. S/MIME certificate
In this document the S/MIME certificate profile is defined for
use in the certification of PEC messages done by the providers.
The proposed profile of the S/MIME certificate is based on the
IETF standards [SMIMECERT] and [X509], which in turn are based
on the standard ISO/IEC 9594-8:2001.
6.5.1. Provider-related information (subject)
The information related to the PEC provider holder of the
certificate MUST be inserted in the "Subject:" field (Subject
DN).
More precisely, the Subject DN MUST contain the PEC provider's
name as it is in the "providerName" attribute published in the
PEC providers directory (section 4.5). The providerName MUST be
present in the CommonName or OrganizationName attributes of the
Subject field in the certificate.
Certificates MUST contain an Internet mail address, which MUST
have a value in the subjectAltName extension, and SHOULD NOT be
present in the Subject Distinguished Name.
Valid subjectDN are:
C=IT, O=AcmePEC S.p.A, CN=Posta Certificata
C=IT, O=ServiziPEC S.p.A, CN=Posta Certificata
Valorization of other attributes in the Subject DN, if present,
MUST be done in compliance with [X509].
6.5.2. Certificate extensions
Extensions that MUST be present in the S/MIME certificate are:
o Key Usage
o Authority Key Identifier
o Subject Key Identifier
o Subject Alternative Name
The Basic Constraints extension (Object ID:2.5.29.19) MUST NOT
be present.
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The valorization of the above listed extensions for the
described profile follows.
The Key Usage extension (Object ID: 2.5.29.15) MUST have the
digitalSignature bit (bit 0) activated and MUST be marked as
critical. The extension MAY contain other active bits
corresponding to different Key Usage, as long as that doesn't
contrast with the indications in [X509].
The Authority Key Identifier (Object ID:2.5.29.35) MUST contain
at least the keyIdentifier field, and MUST NOT be marked as
critical.
The Subject Key Identifier extension (Object ID: 2.5.29.14) MUST
contain at least the keyIdentifier field, and MUST NOT be marked
as critical.
The Subject Alternative Name (Object ID: 2.5.29.17) MUST contain
at least the rfc822Name field, and MUST NOT be marked as
critical.
Adding other extensions that have not been described in this
document is to be considered OPTIONAL, as long as it remains
compliant with [X509]; such added extension MUST NOT be marked
as critical.
6.5.3. Example
Following is an example of an S/MIME certificate compliant with
the minimal requisites described in this profile. Values used
are of fictitious providers generated for example purposes only.
6.5.3.1. General-use certificate in annotated version
An asterisk near the label of an extension means that such an
extension has been marked as critical.
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VERSION: 3
SERIAL: 11226 (0x2bda)
INNER SIGNATURE:
ALG. ID: id-sha1-with-rsa-encryption
PARAMETER: 0
ISSUER:
Country Name: IT
Organization Name: Certifier 1
Organizational Unit Name: Certification Service Provider
Common Name: Certifier S.p.A.
VALIDITY:
Not Before: Oct 5, 04 09:04:23 GMT
Not After: Oct 5, 05 09:04:23 GMT
SUBJECT:
Country Name: IT
Organization Name: AcmePEC S.p.A.
Common Name: Certified Mail
PUBLIC KEY: (key size is 1024 bits)
ALGORITHM:
ALG. ID: id-rsa-encryption
PARAMETER: 0
|MODULUS: 0x00afbeb4 5563198a aa9bac3f 1b29b5be
| 7f691945 89d01569 ca0d555b 5c33d7e9
| ...
| d15ff128 6792def5 b3f884e6 54b326db
| cf
|EXPONENT: 0x010001
|EXTENSIONS:
| Subject Alt Name:
| RFC Name: posta-certificata@acmepec.it
| Key Usage*: Digital Signature
| Authority Key Identifier: 0x12345678 aaaaaaaa bbbbbbbb
cccccccc
dddddddd
| Subject Key Identifier: 0x3afae080 6453527a 3e5709d8 49a941a8
a3a70ae1
|SIGNATURE:
ALG. ID: id-sha1-with-rsa-encryption
PARAMETER: 0
VALUE: 0x874b4d25 70a46180 c9770a85 fe7923ce
b22d2955 2f3af207 142b2aba 643aaa61
...
d8fd10b4 c9e00ebc c089f7a3 549a1907
ff885220 ce796328 b0f8ecac 86ffb1cc
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6.5.3.2. General-use certificate in dump asn.1
0 30 794: SEQUENCE {
4 30 514: SEQUENCE {
8 A0 3: [0] {
10 02 1: INTEGER 2
: }
13 02 2: INTEGER 11226
17 30 13: SEQUENCE {
19 06 9: OBJECT IDENTIFIER
: sha1withRSAEncryption (1 2 840 113549 1 1 5)
30 05 0: NULL
: }
32 30 101: SEQUENCE {
34 31 11: SET {
36 30 9: SEQUENCE {
38 06 3: OBJECT IDENTIFIER countryName (2 5 4 6)
43 13 2: PrintableString 'IT'
: }
: }
47 31 28: SET {
49 30 26: SEQUENCE {
51 06 3: OBJECT IDENTIFIER organizationName (2 5 4
10)
56 13 19: PrintableString 'Certificatore 1'
: }
: }
77 31 22: SET {
79 30 20: SEQUENCE {
81 06 3: OBJECT IDENTIFIER organizationalUnitName
(2 5 4 11)
86 13 13: PrintableString 'Certification Service
Provider'
: }
: }
101 31 32: SET {
103 30 30: SEQUENCE {
105 06 3: OBJECT IDENTIFIER commonName (2 5 4 3)
110 13 23: PrintableString 'Certificatore S.p.A.'
: }
: }
: }
135 30 30: SEQUENCE {
137 17 13: UTCTime '041005090423Z'
152 17 13: UTCTime '051005090423Z'
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: }
167 30 66: SEQUENCE {
169 31 11: SET {
171 30 9: SEQUENCE {
173 06 3: OBJECT IDENTIFIER countryName (2 5 4 6)
178 13 2: PrintableString 'IT'
: }
: }
182 31 23: SET {
184 30 21: SEQUENCE {
186 06 3: OBJECT IDENTIFIER organizationName (2 5 4
10)
191 13 14: PrintableString 'AcmePEC S.p.A.'
: }
: }
207 31 26: SET {
209 30 24: SEQUENCE {
211 06 3: OBJECT IDENTIFIER commonName (2 5 4 3)
216 13 17: PrintableString 'Posta Certificata'
: }
: }
: }
235 30 159: SEQUENCE {
238 30 13: SEQUENCE {
240 06 9: OBJECT IDENTIFIER rsaEncryption (1 2 840
113549
1
1 1)
251 05 0: NULL
: }
253 03 141: BIT STRING 0 unused bits
: 30 81 89 02 81 81 00 AF BE B4 55 63 19 8A AA 9B
: AC 3F 1B 29 B5 BE 7F 69 19 45 89 D0 15 69 CA 0D
: 55 5B 5C 33 D7 E9 C8 6E FC 14 46 C3 C3 09 47 DD
: CD 10 74 1D 76 4E 71 14 E7 69 42 BE 1C 47 61 85
: 4D 74 76 DD 0B B5 78 4F 1E 84 DD B4 86 7F 96 DF
: 5E 7B AF 0E CE EA 12 57 0B DF 9B 63 67 4D F9 37
: B7 48 35 27 C2 89 F3 C3 54 66 F7 DA 6C BE 4F 5D
: 85 55 07 A4 97 8C D1 5F F1 28 67 92 DE F5 B3 F8
: [ Another 12 bytes skipped ]
: }
397 A3 123: [3] {
399 30 121: SEQUENCE {
401 30 39: SEQUENCE {
403 06 3: OBJECT IDENTIFIER subjectAltName (2 5 29
17)
408 04 32: OCTET STRING
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: 30 1E 81 1C 70 6F 73 74 61 2D 63 65 72 74 69
66
: 69 63 61 74 61 40 61 63 6D 65 70 65 63 2E 69
74
: }
442 30 14: SEQUENCE {
444 06 3: OBJECT IDENTIFIER keyUsage (2 5 29 15)
449 01 1: BOOLEAN TRUE
452 04 4: OCTET STRING
: 03 02 07 80
: }
458 30 31: SEQUENCE {
460 06 3: OBJECT IDENTIFIER authorityKeyIdentifier
(2 5
29
35)
465 04 24: OCTET STRING
: 30 16 11 11 11 11 AA AA AA AA AA BB BB BB BB
CC
CC
: CC CC DD DD DD DD
: }
491 30 29: SEQUENCE {
493 06 3: OBJECT IDENTIFIER subjectKeyIdentifier (2
5 29
14)
498 04 22: OCTET STRING
: 04 14 3A FA E0 80 64 53 52 7A 3E 57 09 D8 49
A9
: 41 A8 A3 A7 0A E1
: }
: }
: }
: }
522 30 13: SEQUENCE {
524 06 9: OBJECT IDENTIFIER
: sha1withRSAEncryption (1 2 840 113549 1 1 5)
535 05 0: NULL
: }
537 03 257: BIT STRING 0 unused bits
: 87 4B 4D 25 70 A4 61 80 C9 77 0A 85 FE 79 23 CE
: B2 2D 29 55 2F 3A F2 07 14 2B 2A BA 64 3A AA 61
: 1F F0 E7 3F C4 E6 13 E2 09 3D F0 E1 83 A0 C0 F2
: C6 71 7F 3A 1C 80 7F 15 B3 D6 1E 22 79 B8 AC 91
: 51 83 F2 3A 84 86 B6 07 2B 22 E8 01 52 2D A4 50
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: 9F C6 42 D4 7C 38 B1 DD 88 CD FC E8 C3 12 C3 62
: 64 0F 16 BF 70 15 BC 01 16 78 30 2A DA FA F3 70
: E2 D3 0F 00 B0 FD 92 11 6C 55 45 48 F5 64 ED 98
: [ Another 128 bytes skipped ]
: }
6.6. PEC providers directory
The contents of the PEC providers directory can be queried via
HTTP on SSL exclusively by licensed providers that have the
necessary user certificates; this access modality guarantees
authenticity, integrity and discretion of data.
7. PEC system client technical and functional prerequisites
This section lists the prerequisites that must be respected by a
client in order to guarantee the minimal operative
functionalities to the user of a general PEC system:
o handling of access and delivery points through secure
channels;
o handling of user authentication in message dispatch and
reception phases;
o support for MIME format according to [MIME1] and [MIME5];
o handling of media type "message.rfc822";
o support for "ISO-8859-1 (Latin-1)" character set;
o support for S/MIME v3 standard, as in [SMIMEV3], for
verification of signatures applied to envelopes and
notifications.
8. Security Considerations
All security considerations from [CMS] and [SMIMEV3] apply to
applications that use procedures described in this document.
The centralized LDAP server is a critical point for the security
of the whole PEC system. An attack could compromise the whole
PEC system. PEC providers that periodically download the LDIF
file SHOULD use the best security technology to protect it from
local attacks. A PEC provider could be compromised if an
attacker changed a certificate or modified the list of domains
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associated to it in the LDIF file that was copied to the PEC
provider system.
When verifying the validity of the signature of a message, the
recipient system SHOULD verify that the certificate included in
the [CMS] message is present in the LDIF file (section 4.5), and
that the domain extracted by the [EMAIL] "From:" header is
listed in the managedDomains attribute associated to said
certificate.
A Hardware Security Module compliant with the FIPS-140-2 is
REQUIRED to store the private key of each PEC provider.
9. IANA Considerations
This document does not require any consideration from the IANA.
10. References
10.1. Normative References
[CMS] Housley, R., "Cryptographic Message Syntax (CMS)",
RFC 3852, Vigil Security, July 2004
[EMAIL] P. Resnick, Editor, "Internet Message Format", RFC
5322, QUALCOM Incorporated, April 2001
[LDAP] Legg, S., Editor, "Lightweight Directory Access
Protocol (LDAP): Syntaxes and Matching Rules",
RFC 4516, eB2Bcom, June 2006
[LDIF] Good, G., "The LDAP Data Interchange Format (LDIF) -
Technical Specification", RFC 2849, iPlanet e-commerce
Solutions, June 2000
[MIME1] Freed, N., and N. Borenstein, "Multipurpose Internet
Mail Extensions (MIME) Part One: Format of Internet
Message Bodies", RFC 2045, November 1996
[MIME5] Freed, N., and N. Borenstein, "Multipurpose Internet
Mail Extensions (MIME) Part Five: Conformance Criteria
and Examples", RFC 2049, November 1996
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[REQ] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Harvard
University, March 1997
[SHA1] Eastlake, D., and P. Jones, "US Secure Hash Algorithm
1 (SHA1)", RFC 3174, September 2001
[MIME-SECURE] Galvin, J., S. Murphy, S. Crocker, and N. Freed
"Security Multiparts for MIME: Multipart/Signed and
Multipart/Encrypted", RFC 1847, October 1995
[SMIMEV3] Ramsdell, B. Editor, "Secure/Multipurpose Internet
Mail Extensions (S/MIME) Version 3.1 Message
Specifications", RFC 3851, Sendmail, Inc., July 2004
[SMIMECERT] Ramsdell, B., Editor, "Secure/Multipurpose internet
Mail Extensions (S/MIME) Version 3.1 Certificate
Handling", RFC 3850, Sendmail, Inc., July 2004
[SMTP] Klensin, J. Editor, "Simple Mail Transfer Protocol",
RFC 5321, AT&T Laboratories, April 2001
[SMTP-DSN] Moore, K., "Simple Mail Transfer Protocol (SMTP)
Service Extension for Delivery Status Notifications
(DSNs)", RFC 3461, University of Tennessee, January
2003
[SMTP-TLS] Hoffman, P., "SMTP Service Extension for Secure SMTP
over Transport Layer Security", RFC 3207, Internet
Mail Consortium, February 2002
[X509] Cooper, D., S. Santesson, S. Farrell, S. Boeyen, R.
Housley, and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation
List (CRL) Profile", RFC 5280, May 2008
11. Acknowledgments
The Italian document, on which the present document is based, is
a product of the collaboration of many, with the supervision of
the National Center for Informatics in the Public Administration
of Italy (CNIPA).
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APPENDIX A: Italian fields and values in English
X-Riferimento-Message-ID X-Reference-Message-ID
X-Ricevuta X-Notification
non-accettazione non-acceptance
accettazione acceptance
preavviso-errore-consegna advance-notice-delivery-error
presa-in-carico take-charge
rilevazione-virus virus-detection
errore-consegna delivery-error
avvenuta-consegna message-delivered
X-VerificaSicurezza X-SecurityVerification
X-Trasporto X-Transport
posta-certificata certified-mail
errore error
X-VerificaSicurezza X-SecurityVerification
errore error
X-TipoRicevuta X-NotificationType
completa complete
breve brief
sintetica concise
certificatore certificator
Subject values:
Accettazione ACCEPTANCE
Posta certificata CERTIFIED MAIL
Presa in carico TAKE IN CHARGE
Consegna DELIVERY
Anomalia messaggio MESSAGE ANOMALY
Problema di sicurezza SECURITY PROBLEM
Avviso di non accettazione NON-ACCEPTANCE
NOTIFICATION
Avviso di non accettazione per virus VIRUS DETECTION
INDUCED NON
-ACCEPTANCE
NOTIFICATION
Avviso di mancata consegna NON-DELIVERY
NOTIFICATION
Avviso di mancata consegna per virus NON-DELIVERY
NOTIFICATION
DUE TO VIRUS
Avviso di mancata consegna per sup. tempo massimo
NON-DELIVERY
NOTIFICATION
DUE TO TIMEOUT
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Authors' Addresses
Francesco Gennai
ISTI-CNR
Via Moruzzi, 1
56126 Pisa
Italy
Email: francesco.gennai@isti.cnr.it
Alba Shahin
ISTI-CNR
Via Moruzzi, 1
56126 Pisa
Italy
Email: alba.shahin@isti.cnr.it
Claudio Petrucci
CNIPA
Via Isonzo 21/B
00198 Roma
Italy
Email: c.petrucci@cnipa.it
Alessandro Vinciarelli
CNIPA
Via Isonzo 21/B
00198 Roma
Italy
Email: alessandro.vinciarelli@cnipa.it
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technology described in this document or the extent to which any
license under such rights might or might not be available; nor
Gennai et al. Expires April 2009 [Page 61]
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does it represent that it has made any independent effort to
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respect to rights in RFC documents can be found in BCP 78 and
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The IETF invites any interested party to bring to its attention
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Gennai et al. Expires April 2009 [Page 62]
