Secure Inter-Domain Routing R. Austein
Internet-Draft ISC
Intended status: Standards Track G. Huston
Expires: February 6, 2010 APNIC
S. Kent
M. Lepinski
BBN
August 5, 2009
Manifests for the Resource Public Key Infrastructure
draft-ietf-sidr-rpki-manifests-05.txt
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Abstract
This document defines a "manifest" for use in the Resource Public Key
Infrastructure. A manifest is a signed object that contains a
listing of all the signed objects in the repository publication point
associated with an authority responsible for publishing in the
repository. For each certificate, or other forms of signed objects
issued by the authority that are published at this repository
publication point, the manifest contains both the name of the file
containing the object, and a hash of the file content. Manifests are
intended to expose potential attacks against relying parties of the
Resource Public Key Infrastructure, such as a man-in-the middle
attack of withholding repository data from relying party access, or
replaying stale repository data to a relying party's access request.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Manifest Scope . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Manifest Signing . . . . . . . . . . . . . . . . . . . . . . . 5
4. Manifest Syntax . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Signed-Data Content Type . . . . . . . . . . . . . . . . . 6
4.1.1. version . . . . . . . . . . . . . . . . . . . . . . . 6
4.1.2. digestAlgorithms . . . . . . . . . . . . . . . . . . . 6
4.1.3. encapContentInfo . . . . . . . . . . . . . . . . . . . 7
4.1.4. certificates . . . . . . . . . . . . . . . . . . . . . 9
4.1.5. crls . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.1.6. signerInfos . . . . . . . . . . . . . . . . . . . . . 9
4.2. ASN.1 . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5. Manifest Generation . . . . . . . . . . . . . . . . . . . . . 14
5.1. CA Manifest Generation . . . . . . . . . . . . . . . . . . 14
5.2. End Entity Manifest Generation . . . . . . . . . . . . . . 15
5.3. Common Considerations for Manifest Generation . . . . . . 16
6. Processing Certificate Requests . . . . . . . . . . . . . . . 17
7. Manifest Validation . . . . . . . . . . . . . . . . . . . . . 17
8. Relying Party Use of Manifests . . . . . . . . . . . . . . . . 19
8.1. Tests for Determining Manifest State . . . . . . . . . . . 19
8.2. Missing Manifests . . . . . . . . . . . . . . . . . . . . 20
8.3. Invalid Manifests . . . . . . . . . . . . . . . . . . . . 21
8.4. Stale Manifests . . . . . . . . . . . . . . . . . . . . . 22
8.5. Mismatch between Manifest and Publication Point . . . . . 22
8.6. Hash Values Not Matching Manifests . . . . . . . . . . . . 23
9. Publication Repositories . . . . . . . . . . . . . . . . . . . 24
10. Security Considerations . . . . . . . . . . . . . . . . . . . 25
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 25
13. Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
13.1. Changes in the draft from -04 to -05 . . . . . . . . . . . 26
14. Normative References . . . . . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 27
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1. Introduction
The Resource Public Key Infrastructure (RPKI) [I-D.sidr-arch] makes
use of a distributed repository system [I-D.sidr-repos-struct] to
make available a variety of objects needed by relying parties (RPs)
such as Internet service providers (ISPs). Because all of the
objects stored in the repository system are digitally signed by the
entities that created them, attacks that modify these objects are
detectable by RPs. However, digital signatures provide no protection
against attacks that substitute "stale" versions of signed objects
(i.e., objects that were valid and have not expired, but have since
been superseded) or attacks that remove an object that should be
present in the repository. To assist in the detection of such
attacks, the RPKI repository system will make use of a new signed
object called a "manifest".
A manifest is a signed object that contains a listing of all the
signed objects in the repository publication point associated with an
authority responsible for publishing in the repository. For each
certificate, Certificate Revocation List (CRL), or other signed
object, such as a Route Origination Authorization (ROA), issued by an
authority, the authority's manifest contains both the name of the
file containing the object, and a hash of the file content.
Manifests allow a RP to obtain sufficient information to detect
whether the retrieval of objects from an RPKI repository has been
compromised by unauthorized object removal, or by the substitution of
"stale" versions of objects. Manifests are designed to be used both
for Certification Authority (CA) publication points in repositories,
that contain subordinate certificates, CRLs and other signed objects,
and End Entity (EE) publication points in repositories that contain
signed objects.
Manifests are modeled on CRLs, as the issues involved in detecting
stale manifests, and detection of potential attacks using manifest
replays, etc are similar to those for CRLs. The syntax of the
manifest payload differs from CRLs, since RPKI repositories can
contain objects not covered by CRLs, such as digitally signed
objects, such as ROAs.
1.1. Terminology
It is assumed that the reader is familiar with the terms and concepts
described in "Internet X.509 Public Key Infrastructure Certificate
and Certificate Revocation List (CRL) Profile" [RFC5280]> and "X.509
Extensions for IP Addresses and AS Identifiers" [RFC3779].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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document are to be interpreted as described in RFC 2119.
2. Manifest Scope
In the case of a CA's manifest for its associated publication
repository, the manifest contains the current published certificates
issued by this CA, the most recent CRL issued by this CA, and all
objects that are signed using a "single-use" EE certificate (i.e.,
the SIA extension of the EE certificate has an accessMethod OID of
id-ad-signedObject), where the EE certificate was issued by this CA.
In the case where multiple CAs share a common publication point, as
may be the case when an entity performs a staged key-rollover
operation, the repository publication will contain multiple
manifests. In such a scenario, each manifest describes only the
collection of published products of its associated CA.
In the case of a "multi-use" EE certificate, where an EE has a
defined publication repository (i.e., the SIA extension of the EE
certificate has an accessMethod OID of id-ad-signedObjectRepository),
the EE's manifest contains all published objects that have been
signed by the EE's key, and the accessMethod id-as-rpkiManifest
points to the publication point of the EE's manifest.
3. Manifest Signing
A CA's manifest is verified using an EE certificate that is
designated in [I-D.sidr-res-certs] as a "single-use" EE certificate.
The SIA field of the "single-use" EE certificate contains the access
method OID of id-ad-signedObject.
The CA MAY chose to sign only one manifest with the private key of
the EE certificate, and generate a new EE certificate for each new
version of the manifest. This form of use of a "single-use" EE
certificate is termed a "one-time-use" EE certificate.
Alternatively the CA MAY chose to use the same EE certificate's
private key to sign a sequence of manifests. Because only a single
manifest is current at any point in time, the EE certificate is used
only to verify a single object at a time. As long as the sequence of
objects signed by this EE certificate's private key are published as
the same named object, so that the SIA accessMethod id-ad-
signedObject value can refer to the current instance of the sequence
of such objects, then this sequential multiple use of this "single-
use" EE certificate is also valid. This form of use of a "single-
use" EE certificate is termed a "sequential-use" EE certificate.
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A "multi-use" EE's manifest of it's publication repository is signed
with the private key of the EE certificate.
4. Manifest Syntax
A manifest is a Cryptographic Message Syntax (CMS) [RFC3852] signed-
data object. The general format of a CMS object is:
ContentInfo ::= SEQUENCE {
contentType ContentType,
content [0] EXPLICIT ANY DEFINED BY contentType }
ContentType ::= OBJECT IDENTIFIER
A Manifest is a signed-data object. The ContentType used is the
signed-data type of id-data, namely the id-signedData OID,
1.2.840.113549.1.7.2. [RFC3852]
4.1. Signed-Data Content Type
According to the CMS specification, signed-data content types shall
have the ASN.1 type SignedData:
SignedData ::= SEQUENCE {
version CMSVersion,
digestAlgorithms DigestAlgorithmIdentifiers,
encapContentInfo EncapsulatedContentInfo,
certificates [0] IMPLICIT CertificateSet OPTIONAL,
crls [1] IMPLICIT RevocationInfoChoices OPTIONAL,
signerInfos SignerInfos }
DigestAlgorithmIdentifiers ::= SET OF DigestAlgorithmIdentifier
SignerInfos ::= SET OF SignerInfo
4.1.1. version
The version is the syntax version number. It MUST be 3,
corresponding to the signerInfo structure having version number 3.
4.1.2. digestAlgorithms
The digestAlgorithms set contains a set of OIDs of the algorithms
used to sign the data. The algorithms used to sign the data MUST
conform to the RPKI Algorithms and Key Size Profile specification
[I-D.sidr-rpki-algs].
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4.1.3. encapContentInfo
encapContentInfo is the signed content, consisting of a content type
identifier and the content itself.
EncapsulatedContentInfo ::= SEQUENCE {
eContentType ContentType,
eContent [0] EXPLICIT OCTET STRING OPTIONAL }
ContentType ::= OBJECT IDENTIFIER
4.1.3.1. eContentType
The eContentType for a Manifest is defined as id-ct-rpkiManifest, and
has the numerical value of 1.2.840.113549.1.9.16.1.26.
id-smime OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
rsadsi(113549) pkcs(1) pkcs9(9) 16 }
id-ct OBJECT IDENTIFIER ::= { id-smime 1 }
id-ct-rpkiManifest OBJECT IDENTIFIER ::= { id-ct 26 }
4.1.3.2. eContent
The content of a Manifest is defined as follows:
Manifest ::= SEQUENCE {
version [0] INTEGER DEFAULT 0,
manifestNumber INTEGER,
thisUpdate GeneralizedTime,
nextUpdate GeneralizedTime,
fileHashAlg OBJECT IDENTIFIER,
fileList SEQUENCE OF (SIZE 0..MAX) FileAndHash
}
FileAndHash ::= SEQUENCE {
file IA5String
hash BIT STRING
}
4.1.3.2.1. Manifest
The manifestNumber, thisUpdate, and nextUpdate fields are modeled
after the corresponding fields in X.509 CRLs (see [RFC5280]).
Analogous to CRLS, a manifest is nominally valid until the time
specified in nextUpdate or until a manifest is issued with a greater
manifest number, whichever comes first. The revoked EE certificate
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for the previous manifest's signature will be removed from the CRL
when it expires.
If a "one-time-use" EE certificate is employed to verify a manifest,
the EE certificate MUST have an validity period that coincides with
the interval from thisUpdate to nextUpdate, to prevent needless
growth of the CA's CRL.
If a "sequential-use EE certificate is employed to verify a manifest,
the EE certificate's validity period needs to be no shorter than the
nextUpdate time of the current manifest. The extended validity time
raises the possibility of a substitution attack using a stale
manifest, as described in Section 8.4.
4.1.3.2.1.1. version
The version number of the rpkiManifest MUST be 0.
4.1.3.2.1.2. manifestNumber
The manifestNumber field is a sequence number that is incremented
each time a new manifest is issued for a given publication point.
This field is used to allow a RP to detect gaps in a sequence of
published manifest.
4.1.3.2.1.3. thisUpdate
The thisUpdate field contains the time when the manifest was created.
4.1.3.2.1.4. nextUpdate
The nextUpdate field contains the time at which the next scheduled
manifest will be issued. The value of nextUpdate MUST be later than
the value of thisUpdate. If the authority alters any of the items in
the repository publication point, then the authority MUST issue a new
manifest before the nextUpdate time. If a manifest encompasses a
CRL, the nextUpdate field of the manifest MUST match that of the CRL,
as the manifest will be reissued when a new CRL is published. When a
"one-time-use" EE certificate is being used to verify the manifest,
then when a new manifest is issued before the time specified in
nextUpdate of the current manifest, the CA MUST also issue a new CRL
that includes the EE certificate corresponding to the old manifest.
4.1.3.2.1.5. fileHashAlg
The fileHashAlg field contains the OID of the hash algorithm used to
hash the files that the authority has placed into the repository.
The hash algorithm used MUST conform to the RPKI Algorithms and Key
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Size Profile specification [I-D.sidr-rpki-algs].
4.1.3.2.1.6. fileList
The fileList field contains a sequence of FileAndHash pairs, one for
each currently valid signed object that has been issued by the
authority. Each FileAndHash pair contains the name of the file in
the repository that contains the object in question, and a hash of
the file's contents.
4.1.4. certificates
The certificates field MUST be included, and MUST contain the RPKI EE
certificate needed to validate this manifest in the context of the
RPKI.
4.1.5. crls
This field MUST be omitted.
4.1.6. signerInfos
Signer Infos is defined as a SignerInfo, which is defined under CMS
as:
SignerInfo ::= SEQUENCE {
version CMSVersion,
sid SignerIdentifier,
digestAlgorithm DigestAlgorithmIdentifier,
signedAttrs [0] IMPLICIT SignedAttributes OPTIONAL,
signatureAlgorithm SignatureAlgorithmIdentifier,
signature SignatureValue,
unsignedAttrs [1] IMPLICIT UnsignedAttributes OPTIONAL }
4.1.6.1. version
The version number MUST be 3, corresponding with the choice of
SubjectKeyIdentifier for the sid.
4.1.6.2. sid
The sid is defined as:
SignerIdentifier ::= CHOICE {
issuerAndSerialNumber IssuerAndSerialNumber,
subjectKeyIdentifier [0] SubjectKeyIdentifier }
For a Manifest, the sid MUST be a SubjectKeyIdentifier.
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4.1.6.3. digestAlgorithm
The digestAlgorithm field contains the OIDs of the algorithm used to
sign the data. The algorithm used to sign the data MUST conform to
the RPKI Algorithms and Key Size Profile specification
[I-D.sidr-rpki-algs].
4.1.6.4. signedAttrs
The signedAttrs is defined as signedAttributes:
SignedAttributes ::= SET SIZE (1..MAX) OF Attribute
UnsignedAttributes ::= SET SIZE (1..MAX) OF Attribute
Attribute ::= SEQUENCE {
attrType OBJECT IDENTIFIER,
attrValues SET OF AttributeValue }
AttributeValue ::= ANY
The signedAttr element MUST be present and MUST include the content-
type and message-digest attributes. The signer MAY also include the
signing-time signed attribute, the binary-signing-time signed
attribute, or both signing-time attributes. Other signed attributes
that are deemed appropriate MAY also be included. The intent is to
allow additional signed attributes to be included if a future need is
identified. This does not cause an interoperability concern because
unrecognized signed attributes are ignored by the relying party.
The signedAttr MUST include only a single instance of any particular
attribute. Additionally, even though the syntax allows for a SET OF
AttributeValue, in a Manifest the attrValues MUST consist of only a
single AttributeValue.
4.1.6.4.1. Content-Type Attribute
The ContentType attribute MUST be present. The attrType OID for the
ContentType attribute is 1.2.840.113549.1.9.3.
The attrValues for the ContentType attribute in a Manifest MUST be
1.2.840.113549.1.9.16.1.26, matching the eContentType in the
EncapsulatedContentInfo.
4.1.6.4.2. Message-Digest Attribute
The MessageDigest Attribute MUST be present. The attrType OID for
the MessageDigest Attribute is 1.2.840.113549.1.9.4.
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The attrValues for the MessageDigest attribute contains the output of
the digest algorithm applied to the content being signed, as
specified in Section 11.1 of [RFC3852].
4.1.6.4.3. SigningTime Attribute
The SigningTime attribute MAY be present. The presence of absence of
the SigningTime attribute in no way affects the validation of the
Manifest (as specified in Section Section 7).
The attrType OID for the SigningTime attribute is
1.2.840.113549.1.9.5.
The attrValues for the SigningTime attribute is defined as:
id-signingTime OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs9(9) 5 }
SigningTime ::= Time
Time ::= CHOICE {
utcTime UTCTime,
generalizedTime GeneralizedTime }
The Time element specifies the time, based on the local system clock,
at which the digital signature was applied to the content.
4.1.6.4.4. BinarySigningTime Attribute
The signer MAY include a BinarySigningTime attribute, specifying the
time at which the digital signature was applied to the content. If
both the BinarySigningTime and SigningTime attributes are present,
the time that is represented by the binary-signing-time attribute
MUST represent the same time value as the signing-time attribute.
The presence or absence of the Binary-SigningTime attribute in no way
affects the validation of the Manifest (as specified in Section
Section 7).
The binary-signing-time attribute is defined in [RFC4049] as:
id-aa-binarySigningTime OBJECT IDENTIFIER ::= { iso(1)
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
smime(16) aa(2) 46 }
BinarySigningTime ::= BinaryTime
BinaryTime ::= INTEGER (0..MAX)
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4.1.6.5. signatureAlgorithm
The signatureAlgorithm MUST conform to the RPKI Algorithms and Key
Size Profile specification [I-D.sidr-rpki-algs].
4.1.6.6. signature
The signature value is defined as:
SignatureValue ::= OCTET STRING
The signature characteristics are defined by the digest and signature
algorithms.
4.1.6.7. unsignedAttrs
unsignedAttrs MUST be omitted.
4.2. ASN.1
The following is the ASN.1 specification of the CMS-signed Manifest.
ContentInfo ::= SEQUENCE {
contentType ContentType,
content [0] EXPLICIT ANY DEFINED BY contentType }
ContentType ::= OBJECT IDENTIFIER
id-smime OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
rsadsi(113549) pkcs(1) pkcs9(9) 16 }
id-ct OBJECT IDENTIFIER ::= { id-smime 1 }
id-ct-rpkiManifest OBJECT IDENTIFIER ::= { id-ct 26 }
Manifest ::= SEQUENCE {
version [0] INTEGER DEFAULT 0,
manifestNumber INTEGER,
thisUpdate GeneralizedTime,
nextUpdate GeneralizedTime,
fileHashAlg OBJECT IDENTIFIER,
fileList SEQUENCE OF (SIZE 0..MAX) FileAndHash}
FileAndHash ::= SEQUENCE {
file IA5String
hash BIT STRING}
id-signedData OBJECT IDENTIFIER ::= { iso(1) member-body(2)
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us(840) rsadsi(113549) pkcs(1) pkcs7(7) 2 }
SignedData ::= SEQUENCE {
version CMSVersion,
digestAlgorithms DigestAlgorithmIdentifiers,
encapContentInfo EncapsulatedContentInfo,
certificates [0] IMPLICIT CertificateSet OPTIONAL,
crls [1] IMPLICIT RevocationInfoChoices OPTIONAL,
signerInfos SignerInfos }
DigestAlgorithmIdentifiers ::= SET OF DigestAlgorithmIdentifier
SignerInfos ::= SET OF SignerInfo
SignerInfo ::= SEQUENCE {
version CMSVersion,
sid SignerIdentifier,
digestAlgorithm DigestAlgorithmIdentifier,
signedAttrs [0] IMPLICIT SignedAttributes OPTIONAL,
signatureAlgorithm SignatureAlgorithmIdentifier,
signature SignatureValue,
unsignedAttrs [1] IMPLICIT UnsignedAttributes OPTIONAL }
SignerIdentifier ::= CHOICE {
issuerAndSerialNumber IssuerAndSerialNumber,
subjectKeyIdentifier [0] SubjectKeyIdentifier }
SignedAttributes ::= SET SIZE (1..MAX) OF Attribute
UnsignedAttributes ::= SET SIZE (1..MAX) OF Attribute
Attribute ::= SEQUENCE {
attrType OBJECT IDENTIFIER,
attrValues SET OF AttributeValue }
AttributeValue ::= ANY
SignatureValue ::= OCTET STRING
id-contentType OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs9(9) 3 }
ContentType ::= OBJECT IDENTIFIER
id-messageDigest OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs9(9) 4 }
MessageDigest ::= OCTET STRING
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id-signingTime OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs9(9) 5 }
SigningTime ::= Time
Time ::= CHOICE {
utcTime UTCTime,
generalizedTime GeneralizedTime }
id-aa-binarySigningTime OBJECT IDENTIFIER ::= { iso(1)
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
smime(16) aa(2) 46 }
BinarySigningTime ::= BinaryTime
BinaryTime ::= INTEGER (0..MAX)
5. Manifest Generation
5.1. CA Manifest Generation
Each CA in the RPKI publishes the certificates and CRLs it issues at
a publication point in the RPKI repository system. To create a
manifest, each CA MUST perform the following steps:
1. If no key pair exists, or if using a "one-time-use" EE
certificate with a new key pair, then generate a key pair.
2. If using a "one-time-use" EE certificate, or if a key pair was
generated in step 1, issue a "single-use" EE certificate for this
key pair to enable relying parties to verify the signature on the
manifest.
* This EE certificate has an SIA extension access description
field with an accessMethod OID value of id-ad-signedobject
where the associated accessLocation references the publication
point of the manifest as an object URL.
* This EE certificate MUST describe its IP number resources
using the "inherit" attribute, rather than explicit
description of a resource set.
* In the case of a "one-time-use" EE certificate, the validity
times of the EE certificate SHOULD exactly match the
thisUpdate and nextUpdate times of the manifest, and MUST
encompass the interval from thisUpdate to nextUpdate.
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* In the case of a "sequential-use" EE certificate the validity
times of the EE certificate MUST encompass the time interval
from thisUpdate to nextUpdate.
3. The EE certificate SHOULD NOT be published in the authority's
repository publication point.
4. Construct the manifest content. Note that the manifest does not
include a self reference (i.e., its own file name and hash),
since it would be impossible to compute the hash of the manifest
itself prior to it being signed. The manifest content is
described in Section 4.1.3.2.1. The manifest's fileList includes
the file names and hash pair for all objects associated with this
CA that have been published at the CA's repository publication
point. The collection of objects to be included in the manifest
includes all subordinate certificates issued by this CA that are
published at the CA's repository publication point, the most
recent CRL issued by the CA , and all objects verified by
"single-use" EE certificates that were issued by this CA that are
published at the CA's repository publication point.
5. Encapsulate the Manifest content using the CMS SignedData content
type (as specified in Section Section 4), sign the manifest using
the private key corresponding to the EE certificate, and publish
the manifest in repository system publication point that is
described by the manifest.
6. In the case of a key pair that is to be used only once, in
conjunction with a "one-time-use" EE certificate, the private key
associated with this key pair SHOULD now be destroyed.
5.2. End Entity Manifest Generation
EE repository publication points are only used in conjunction with
"multi-use" EE Certificates. In this case the EE Certificate has two
accessMethods specified in its SIA field. The id-ad-
signedObjectRepository accessMethod has an associated accessLocation
that points to the repository publication point of the objects signed
by this EE certificate, as specified in [I-D.sidr-res-certs]. The
id-ad-rpkiManifest accessMethod has an associated access location
that points to the manifest object as an object URL, that is
associated with this repository publication point. This manifest
describes all the signed objects that are to be found in that
publication point that have been signed by this EE certificate, and
the hash value of each product (excluding the manifest itself).
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To create a manifest, each "multi-use" EE MUST perform the following
steps:.
o Construct the Manifest content. Note that the manifest does not
include a self reference (i.e., its own file name and hash), since
it would be impossible to compute the hash of the manifest itself
prior to it being signed. The manifest content is described in
Section 4.1.3.2.1. The manifest's fileList includes the file
names and hash pair for all objects verified using that EE
certificate that have been published at the EE's repository
publication point.
o Encapsulate the Manifest content using the CMS SignedData content
type (as specified in Section Section 4), sign the manifest using
the EE certificate, and publish the manifest in repository system
publication point that is described by the manifest.
"Single Use" EE certificates (EE certificates with an SIA
accessMethod OID of id-as-signedObject) do not have repository
publication points. The object signed by the "Single Use" EE
certificate is published in the repository publication point of the
CA certificate that issued the EE certificate, and is listed in the
corresponding manifest for this CA certificate.
5.3. Common Considerations for Manifest Generation
o A new manifest MUST be issued on or before the nextUpdate time.
o An authority MUST issue a new manifest in conjunction with the
finalization of changes made to objects in the publication point.
An authority MAY perform a number of object operations on a
publication repository within the scope of a repository change
before issuing a single manifest that covers all the operations
within the scope of this change. Repository operators SHOULD
implement some form of synchronization function on the repository
to ensure that relying parties who are performing retrieval
operations on the repository are not exposed to intermediate
states during changes to the repository and the associated
manifest.
o Since the manifest object URL is included in the SIA of issued
certificates then a new manifest MUST NOT invalidate the manifest
object URL of previously issued certificates. This implies that
the manifest's publication name in the repository, in the form of
an object URL, is one that is unchanged across manifest generation
cycles.
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o In the case of a CA publication point manifest, when the entity is
performing a key rollover the entity MAY chose to have multiple
CAs publishing at the same publication point. In this case there
will be one manifest associated with each active CA that is
publishing into the common repository publication point.
o In the case of an EE publication point the manifest lists all
published objects verified using that EE certificate. Multiple
EEs may share a common repository publication point, in which case
there will be one manifest associated with each active EE that is
publishing into the common repository publication point.
6. Processing Certificate Requests
When an EE certificate is intended for use in verifying multiple
objects, the certificate request for the EE certificate MUST include
in the SIA of the request an access method OID of id-ad-
signedObjectRepository where the associated access location refers to
the publication point for objects signed by this EE certificate, and
MUST include in the SIA of the request an access method OID of id-ad-
rpkiManifest, where the associated access location refers to the
publication point of the manifest that is associated with published
objects that are verified using this EE certificate
[I-D.sidr-res-certs].
When an EE certificate is used to sign a single object, the
certificate request for the EE certificate MUST include in the SIA of
the request an access method OID of id-ad-signedObject, where the
associated access location refers to the publication point of the
single object that is verified using this EE certificate. The
certificate request MUST NOT include in the SIA of the request the
access method OID of id-ad-rpkiManifest.
In accordance with the provisions of [I-D.sidr-res-certs], all
certificate issuance requests for a CA certificate SHOULD include in
the SIA of the request the id-ad-caRepository access method, and also
the id-ad-rpkiManifest access method that references the intended
publication point of the manifest in the associated access location
in the request.
The issuer MUST either honor these values in the issued certificate
or reject the request entirely.
7. Manifest Validation
To determine whether a manifest is valid, the relying party must
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perform the following checks:
1. Verify that the Manifest complies with this specification. In
particular, verify the following:
a. The contentType of the CMS object is SignedData (OID
1.2.840.113549.1.7.2)
b. The version of the SignedData object is 3.
c. The digestAlgorithm in the SignedData object conforms to the
RPKI Algorithms and Key Size Profile specification
[I-D.sidr-rpki-algs].
d. The certificates field in the SignedData object is present
and contains an EE certificate whose Subject Key Identifier
(SKI) matches the sid field of the SignerInfo object.
e. The crls field in the SignedData object is omitted.
f. The eContentType in the EncapsulatedContentInfo is id-ad-
rpkiManifest (OID 1.2.840.113549.1.9.16.1.26).
g. The version of the rpkiManifest is 0.
h. In the rpkiManifest, thisUpdate precedes nextUpdate.
i. The version of the SignerInfo is 3.
j. The digestAlgorithm in the SignerInfo object conforms to the
RPKI Algorithms and Key Size Profile specification
[I-D.sidr-rpki-algs].
k. The signatureAlgorithm in the SignerInfo object conforms to
the RPKI Algorithms and Key Size Profile specification
[I-D.sidr-rpki-algs].
l. The signedAttrs field in the SignerInfo object is present and
contains both the ContentType attribute (OID
1.2.840.113549.1.9.3) and the MessageDigest attribute (OID
1.2.840.113549.1.9.4).
m. The unsignedAttrs field in the SignerInfo object is omitted.
2. Use the public key in the EE certificate to verify the signature
on the Manifest.
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3. Verify that the EE certificate is a valid end-entity certificate
in the resource PKI by constructing a valid certificate path to a
trust anchor. (See [I-D.sidr-res-certs] for more details.)
If the above procedure indicates that the manifest is invalid, then
the manifest MUST be discarded and treated as though no manifest were
present.
8. Relying Party Use of Manifests
The goal of the relying party is to determine which signed objects to
use for routing-related tasks, (e.g., which ROAs to use in the
construction of route filters). Ultimately, this is a matter of
local policy. However, in the following sections, we describe a
sequence of tests that the relying party SHOULD perform to determine
the manifest state of the given publication point. We then discuss
the risks associated with using signed objects in the publication
point, given the manifest state; and provide suitable warning text
that should placed in a user-accessible log file. It is the
responsibility of the relying party to weigh these risks against the
risk of routing failure that could occur if valid data is rejected,
and construct a suitable local policy. Note that if a certificate is
deemed unfit for use do to local policy, then any descendant object
that is validated using this certificate should also be deemed unfit
for use (regardless of the status of the manifest at its own
publication point).
8.1. Tests for Determining Manifest State
For a given publication point, the relying party should perform the
following tests to determine the manifest state of the publication
point:
1. For each entity using this publication point, select the entity's
manifest having highest manifestNumber among all valid manifests
(where manifest validity is defined in Section Section 7).
* If the publication point does not contain a valid manifest,
see Section Section 8.2. Lacking a valid manifest, the
following tests cannot be performed.
2. Check that the current time is between thisUpdate and nextUpdate.
* If the current time does not lie within this interval then see
Section 8.4, but still continue with the following tests.
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3. Check that every file at the publication point appears in one and
only one manifest, and that every file listed in each manifest
appears at the publication point.
* If there exists files at the publication point that do not
appear on any manifest, or files listed in a manifest that do
not appear at the publication point then see Section 8.5 but
still continue with the following test.
4. Check that listed hash value of every file listed in each
manifest matches the value obtained by hashing the file at the
publication point.
* If there exist files at the publication point whose hash does
not match the hash value listed in the manifest, then see
Section 8.6.
For a particular signed object, if all of the following conditions
hold:
* the manifest for its publication, and the associated
publication point, pass all of the above checks;
* the signed object is valid; and
* the manifests for every certificate on the certificate path
used to validate the signed object, and the associated
publication points, pass all of the above checks;
then the relying party can conclude that no attack against the
repository system has compromised the given signed object, and the
signed object MUST be treated as valid.
8.2. Missing Manifests
The absence of a valid manifest at a publication point could occur
due to an error by the publisher or due to (malicious or accidental)
deletion or corruption of all valid manifests.
When no valid manifest is available, there is no protection against
attacks that delete signed objects or replay old versions of signed
objects. All signed objects at the publication point, and all
descendant objects that are validated using a certificate at this
publication point should be viewed as somewhat suspect, but may be
used by the relying party, as per local policy.
The primary risk in using signed objects at this publication point is
that a deleted CRL causes the relying party to improperly treat a
revoked certificate as valid (and thus rely upon signed objects that
are validated using that certificate). This risk is somewhat
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mitigated if the CRL for this publication point has a short time
between thisUpdate and nextUpdate (and the current time is within
this interval). The risk in discarding signed objects at this
publication point is that the relying party may incorrectly discard a
large number of valid objects. This gives significant power to an
adversary that is able to delete all manifests at the publication
point.
Regardless of whether signed objects from this publication are deemed
fit for use by the relying party, this situation should result in a
warning to the effect that: "No manifest is available for <pub point
name>, and thus there may have been undetected deletions or replay
substitutions from the publication point."
In the case where the relying party has access to a local cache of
previously issued manifests that are valid, the relying party MAY use
the most recently previously issued valid manifests for this RPKI
repository publication collection in this case for each entity that
publishes at his publication point.
8.3. Invalid Manifests
The presence of invalid manifests at a publication point could occur
due to an error by the publisher or due to (malicious or accidental)
corruption of a valid manifest. An invalid manifest MUST never be
used even if the manifestNumber is greater than that on valid
manifests.
There are no risks associated with using signed objects at a
publication point containing an invalid manifest, provided that valid
manifests the collectively cover all the signed objects are also
present.
If an invalid manifest is present at a publication point that also
contains one or more valid manifests, this situation should result in
a warning to the effect that: "An invalid manifest was found at <pub
point name>, this indicates an attack against the publication point
or an error by the publisher. Processing for this publication point
will continue using the most recent valid manifest."
In the case where the relying party has access to a local cache of
previously issued manifests that are valid, the relying party MAY use
the locally cached most recently previously issued valid manifest
issued by the entity that issued the invalid manifest in this case.
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8.4. Stale Manifests
A manifest is considered stale if the current time is after the
nextUpdate time for the manifest. This could be due to publisher
failure to promptly publish a new manifest, or due to (malicious or
accidental) corruption of a more recent manifest.
All signed objects at the publication point, and all descendant
objects that are validated using a certificate at this publication
point should be viewed as somewhat suspect, but may be used by the
relying party as per local policy.
The primary risk in using signed objects at this publication point is
that a newer manifest exists that, if present, would indicate that
certain objects are have been removed or replaced. (e.g., the new
manifest if present might show the existence of a newer CRL and the
removal of several revoked certificates). Thus use of objects on a
stale manifest may cause the relying party to incorrectly treat
several invalid objects as valid. The risk is that a stale CRL
causes the relying party to improperly treat a revoked certificate as
valid. This risk is somewhat mitigated if the time between the
nextUpdate field of the manifest and the current time is short. The
risk in discarding signed objects at this publication point is that
the relying party may incorrectly discard a large number of valid
objects. This gives significant power to an adversary that is able
to prevent the publication of a new manifest at a given publication
point.
Regardless of whether signed objects from this publication are deemed
fit for use by the relying party, this situation should result in a
warning to the effect that: "The manifest for <pub point name> is no
longer current. It is possible that undetected deletions have
occurred at this publication point."
Note that there is also a less common case where the current time is
before the thisUpdate time for the manifest. This case could be due
to publisher error, or a local clock error, and in such a case this
situation should result in a warning to the effect that: "The
manifest found at <pub point name> has an incorrect thisUpdate field.
This could be due to publisher error, or a local clock error, and
processing for this publication point will continue using this
otherwise valid manifest."
8.5. Mismatch between Manifest and Publication Point
If there exist otherwise valid signed objects that do not appear in
any manifest, then provided the manifest is not stale (see Section
Section 8.4) it is likely that their omission is an error by the
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publisher. It is also possible that this state could be the result
of a (malicious or accidental) replacement of a current manifest with
an older, but still valid manifest. However, regarding the
appropriate interpretation such objects, it remains the case that if
the objects were intended to be invalid, then they should have been
revoked using whatever revocation mechanism is appropriate for the
signed object in question.) Therefore, there is little risk in using
such signed objects. If the manifest in question is stale, then
there is a greater risk that the objects in question were revoked
with a missing CRL, whose absence is undetectable since the manifest
is stale. In any case, the use of signed objects not present on a
manifest, or descendant objects that are validated using such signed
objects, is a matter of local policy.
Regardless of whether objects not appearing on a manifest are deemed
fit for use by the relying party, this situation should result in a
warning to the effect that: "The following files are present in the
repository at <pub point name>, but are not on the manifest <file
list>."
If there exist files listed on the manifest that do not appear in the
repository, then these objects are likely to have been improperly
(via malice or accident) deleted from the manifest. A primary
purpose of manifests is to detect such deletions. Therefore, in such
a case this situation should result in a warning to the effect that:
"The following files that should have been present in the repository
at <pub point name>, are missing <file list>. This indicates an
attack against this publication point, or the repository, or an error
by the publisher."
8.6. Hash Values Not Matching Manifests
A file appearing on a manifest with an incorrect hash value could
occur because of publisher error, but it is likely to indicate that a
serious error has occurred.
If an object appeared on a previous valid manifest with a correct
hash value and now appears with an invalid hash value, then it is
likely that the object has been superseded by a new (unavailable)
version of the object. If the object is used there is a risk that
the relying party will be treating a stale object as valid. This
risk is more significant if the object in question is a CRL.
Assuming that the object is validated in the RPKI, the use of these
objects is a matter of local policy.
If an object appears on a manifest with an invalid hash and has never
previously appeared on a manifest, then it is unclear whether the
available version of the object is more or less recent than the
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version whose hash appears in the manifest. If the manifest is stale
(see Section 8.4) then it becomes more likely that the available
version is more recent that the version indicated on the manifest,
but this is never certain. Whether to use such objects is a matter
of local policy. However, in general, it is better to use a possibly
outdated version of the object than to discard the object completely.
While it is a matter of local policy, in the case of CRLs a relying
party should endeavor to use the most recently issued valid CRL even
where the hash value in the manifest matches an older CRL, or does
not match any CRL hand. The thisUpdate field of the CRL can be used
to establish the most recent CRL in the case where a relying party
has more than one valid CRL at hand.
Regardless of whether objects with incorrect hashes are deemed fit
for use by the relying party, this situation should result in a
warning to the effect that: "The following files at the repository
<pub point name> appear on a manifest with incorrect hash values
<file list>. It is possible that these objects have been superseded
by a more recent version. It is very likely that this problem is due
to an attack on the publication point, although it could also be due
to a publisher error."
9. Publication Repositories
The RPKI publication system model requires that every publication
point be associated with one or more CAs or one or more EEs, and be
non-empty. Upon creation of the publication point associated with a
CA, the CA MUST create and publish a manifest as well as a CRL. The
manifest will contain at least one entry, the CRL issued by the CA
upon repository creation. Upon the creation of the publication point
associated with an EE, the EE MUST create and publish a manifest.
The manifest in an otherwise empty repository publication point
associated with an EE will contain no entries in the manifest's
fileList sequence (i.e., the ASN.1 SEQUENCE will have a length of
zero). [I-D.sidr-repos-struct]
For each signed object, the EE certificate used to verify the object
is either a single-use certificate, used to verify a single signed
object, or a multiple-use certificate. In the case of a single-use
EE certificate, the signed object is published in the repository
publication point of the CA that issued the single use EE
certificate, and is listed in the manifest associated with that CA
certificate. In the case where an EE certificate is used to verify
multiple objects, each signed object is published in the EE
certificate's repository publication point and listed in the manifest
associated with the EE certificate.
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10. Security Considerations
Manifests provide an additional level of protection for relying
parties of the repository system. Manifests can assist a relying
party to determine if repository objects have been occluded or other
removed from view, and to determine if an older version of an object
has been substituted for the current object .
Manifests cannot repair the effects of such forms of attempted
corruption of repository retrieval operations, but are capable of
allowing a relying party to determine if a locally maintained copy of
a repository is a complete and up to date copy, even when the
repository retrieval operation is conduction over an insecure
channel. In those cases where the manifest and the retrieved
repository contents differ, the manifest can assist in determining
which repository objects form the difference set in terms of missing,
extraneous or older objects .
The signing structure of a manifest and the use of the nextUpdate
value allows the relying party to determine if the manifest itself is
the subject of attempted alteration. The requirement for every
repository publication point to contain at least one manifest allows
a relying party to determine is the manifest itself has been occluded
from view. Such attacks against the manifest are detectable within
the time frame of the regular schedule of manifest updates. Forms of
replay attack within finer-grained time frames are not necessarily
detectable by the manifest structure .
11. IANA Considerations
[Note to IANA, to be removed prior to publication: there are no IANA
considerations stated in this version of the document.]
12. Acknowledgements
The authors would like to acknowledge the contributions from George
Michelson and Randy Bush in the preparation of the manifest
specification. Additionally, the authors would like to thank Mark
Reynolds and Christopher Small for assistance in clarifying manifest
validation and relying party behavior.
13. Notes
[Note to Reviewers: These notes are part of the working group draft
document, and will be removed prior to publication.]
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13.1. Changes in the draft from -04 to -05
Removed references to RSA and SHA-256 from the specification of the
DigestAlgorithms field of CMS SignedData, the SignatureAlgorithm and
digestAlgorithm fields of the SignerInfo field and from the
fileHashAlg field of the Manifest, replacing them with a reference to
the RPKI Algorithm and Hash Profile, to allow for RPKI-wide algorithm
agility.
14. Normative References
[I-D.sidr-arch]
Lepinski, M. and S. Kent, "An Infrastructure to Support
Secure Internet Routing", draft-ietf-sidr-arch-08.txt
(work in progress), July 2009.
[I-D.sidr-repos-struct]
Huston, G., Loomans, R., and G. Michaleson, "A Profile for
Resource Certificate Repository Structure",
draft-ietf-sidr-repos-struct-02.txt (work in progress),
August 2009.
[I-D.sidr-res-certs]
Huston, G., Michaleson, G., and R. Loomans, "A Profile for
X.509 PKIX Resource Certificates",
draft-ietf-sidr-res-certs-16.txt (work in progress),
February 2009.
[I-D.sidr-rpki-algs]
Huston, G., "A Profile for Algorithms and Key Sizes for
use in the Resource Public Key Infrastructure",
draft-huston-sidr-rpki-algs-00.txt (work in progress),
July 2009.
[RFC3779] Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP
Addresses and AS Identifiers", RFC 3779, June 2004.
[RFC3852] Housley, R., "Cryptographic Message Syntax (CMS)",
RFC 3852, July 2004.
[RFC4049] Housley, R., "BinaryTime: An Alternate Format for
Representing Date and Time in ASN.1", RFC 4049,
April 2005.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
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(CRL) Profile", RFC 5280, May 2008.
Authors' Addresses
Rob Austein
Internet Systems Consortium
950 Charter St.
Redwood City, CA 94063
USA
Email: sra@isc.org
Geoff Huston
Asia Pacific Network Information Centre
33 Park Rd.
Milton, QLD 4064
Australia
Email: gih@apnic.net
URI: http://www.apnic.net
Stephen Kent
BBN Technologies
10 Moulton St.
Cambridge, MA 02138
USA
Email: kent@bbn.com
Matt Lepinski
BBN Technologies
10 Moulton St.
Cambridge, MA 02138
USA
Email: mlepinski@bbn.com
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