Internet Draft ETSI TC-SEC (ETSI)
S/MIME Working Group J Ross (Security & Standards)
expires in six months D Pinkas (Bull)
Target Category: Experimental N Pope (Security & Standards)
July 2000
Electronic Signature Policies
<draft-ietf-smime-espolicies-00.txt>
Status of this Memo
This document is an Internet-Draft and is in full conformance with all
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Abstract
This RFC defines signature policies for electronic signatures.
A signature policy is a set of rules for the creation and validation
of an electronic signature, under which the validity of signature can
be determined. A given legal/contractual context may recognize a
particular signature policy as meeting its requirements.
A signature policy has a globally unique reference, which is bound to
an electronic signature by the signer as part of the signature
calculation.
The signature policy needs to be available in human readable form so
that it can be assessed to meet the requirements of the legal and
contractual context in which it is being applied.
To allow for the automatic processing of an electronic signature
another part of the signature policy specifies the electronic
rules for the creation and validation of the electronic signature in
a computer processable form. In the current document the format of the
signature policy is defined using ASN.1.
The contents of this RFC is based on the signature policy defined in
ETSI ES 201 733 V.1.1.3(2000-05) Copyright (C).
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TABLE OF CONTENTS
Abstract 1
Table of contents 2
1. Introduction 3
2. Major Parties 3
3. Signature Policy Specification 5
3.1 Overall ASN.1 Structure 5
3.2 Signature Validation Policy 6
3.3 Common Rules 7
3.4 Commitment Rules 8
3.5 Signer and Verifier Rules 9
3.5.1 Signer Rules 9
3.5.2 Verifier Rules 10
3.6 Certificate and Revocation Requirements 11
3.6.1 Certificate Requirements 11
3.6.2 Revocation Requirements 13
3.7 Signing Certificate Trust Conditions 14
3.8 TimeStamp Trust Conditions 15
3.9 Attribute Trust Conditions 15
3.10 Algorithm Constraints 16
3.11 Signature Policy Extensions 17
4. Security considerations 18
5. Conformance Requirements 18
6. References 18
7. Authors' Addresses 19
8. Full Copyright Statement 20
Annex A (normative): 21
A.1 Definitions Using X.208 (1988) ASN.1 Syntax 21
A.2 Definitions Using X.680 (1997) ASN.1 Syntax 27
Annex B (informative): 34
B.1 Signature Policy and Signature Validation Policy 34
B.2 Identification of Signature Policy 36
B.3 General Signature Policy Information 36
B.4 Recognized Commitment Types 37
B.5 Rules for Use of Certification Authorities 37
B.5.1 Trust Points 37
B.5.2 Certification Path 38
B.6 Revocation Rules 39
B.7 Rules for the Use of Roles 39
B.7.1 Attribute Values 39
B.7.2 Trust Points for Certified Attributes 39
B.7.3 Certification Path for Certified Attributes 40
B.8 Rules for the Use of Timestamping and Timing 40
B.8.1 Trust Points and Certificate Paths 40
B.8.2 Timestamping Authority Names 40
B.8.3 Timing Constraints - Caution Period 40
B.8.4 Timing Constraints - Timestamp Delay 41
B.9 Rules for Verification Data to be followed 41
B.10 Rules for Algorithm Constraints and Key Lengths 41
B.11 Other Signature Policy Rules 41
B.12 Signature Policy Protection 41
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1. Introduction
This document is intended to cover signature policies which can be
used with electronic signatures for various types of transactions,
including business transactions (e.g. purchase requisition, contract,
and invoice applications). Electronic signatures can be used for any
transaction between an individual and a company, between two
companies, between an individual and a governmental body, etc.
This document is independent of any environment. It can be applied
to any environment e.g. smart cards, GSM SIM cards, special programs
for electronic signatures etc.
The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "MAY", and "OPTIONAL" in this document (in uppercase,
as shown) are to be interpreted as described in [RFC2119].
2.3 Major Parties
The document uses the following terms:
* the Signature Policy Issuer;
* the Signer;
* the Verifier;
* the Arbitrator;
* Trusted Service Providers (TSP);
The Signature Policy Issuer (which is a Trusted Service Provider (TSP))
issues signatures policies that define the technical and procedural
requirements for electronic signature creation, and validation/
verification, in order to meet a particular business need.
The Signer is the entity that creates the electronic signature. When
the signer digitally signs over an signature policy identifier, it
represents a commitment on behalf of the signing entity that the data
being signed is signed under the rules defined by the signature policy.
The Verifier is the entity that validates the electronic signature, it
may be a single entity or multiple entities. The verifier MUST validate
the electronic signature under the rules defined by the electronic signature
policy for the signature to be valid.
An arbitrator, is an entity which arbitrates disputes between a signer
and a verifier. It acts as verifier when it verifies the electronic
signature after it has been previously validated.
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The Trusted Service Providers (TSPs) are one or more entities that help
to build trust relationships between the signer and verifier. Use of TSP
specific services MAY be mandated by signature policy. TSP supporting
services include: user certificates, cross-certificates, timestamping
tokens,CRLs, ARLs, OCSP responses.
A Trusted Service Providers (TSPs) MAY be a Signature Policy Issuer, as
Such, the TSP MUST define the technical and procedural requirements for
electronic signature creation and validation, in order to meet a
particular business need.
The following other TSPs are used to support the
functions defined in this document:
* Certification Authorities;
* Registration Authorities;
* Repository Authorities (e.g. a Directory);
* TimeStamping Authorities;
* One-line Certificate Status Protocol responders;
* Attribute Authorities.
Certification Authorities provide users with public key certificates.
Registration Authorities allows the registration of entities before a
CA generates certificates.
Repository Authorities publish CRLs issued by CAs, , cross-certificates
(i.e. CA certificates) issued by CAs, signature policies
issued by Signature Policy Issuers and optionally public key
certificates (i.e. leaf certificates) issued by CAs.
TimeStamping Authorities attest that some data was formed before a
given trusted time.
One-line Certificate Status Protocol responders (OSCP responders)
provide information about the status (i.e. revoked, not revoked,
unknown) of a particular certificate.
Attributes Authorities provide users with attributes linked to public
key certificates
An Arbitrator is an entity that arbitrates disputes between a signer
and a verifier.
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3. Signature Policy Specification
A signature policy specification includes general information about the
policy, the validation policy rules and other signature policy
information.
This document mandates that:
* an electronic signature must be processed by the signer and
verifier in accordance with the signature policy referenced by
the signer;
* the signature policy referenced by the signer must be
identifiable by an Object Identifier;
* there must exist a specification of the signature policy;
* for a given signature policy there must be one definitive form
of the specification which has a unique binary encoding;
* a hash of the definitive specification, using an agreed
algorithm, must be provided by the signer and checked by the
verifier.
This document defines but does not mandate the form of the signature
policy specification. The signature policy may be specified either:
* in a free form document for human interpretation; or
* in a structured form using an agreed syntax and encoding.
This document defines an ASN.1 based syntax that may be used to define
a structured signature policy. Future versions of this document may
include structured a signature policy specification using XML.
3.1 Overall ASN.1 Structure
The overall structure of a signature policy defined using ASN.1 is
given in this clause. Use of this ASN.1 structure is optional.
This ASN.1 syntax is encoded using the Distinguished Encoding Rules
(DER).
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In this structure the policy information is preceded by an identifier
for the hashing algorithm used to protect the signature policy and
followed by the hash value which must be re-calculated and checked
whenever the signature policy is passed between the issuer and
signer/verifier.
The hash is calculated without the outer type and length fields.
SignaturePolicy ::= SEQUENCE {
signPolicyHashAlg AlgorithmIdentifier,
signPolicyInfo SignPolicyInfo,
signPolicyHash SignPolicyHash OPTIONAL }
SignPolicyHash ::= OCTET STRING
SignPolicyInfo ::= SEQUENCE {
signPolicyIdentifier SignPolicyId,
dateOfIssue GeneralizedTime,
policyIssuerName PolicyIssuerName,
fieldOfApplication FieldOfApplication,
signatureValidationPolicy SignatureValidationPolicy,
signPolExtensions SignPolExtensions
OPTIONAL
}
SignPolicyId ::= OBJECT IDENTIFIER
PolicyIssuerName ::= GeneralNames
FieldOfApplication ::= DirectoryString
The policyIssuerName field identifies the policy issuer in one or more
of the general name forms.
The fieldofApplication is a description of the expected application of
this policy.
The signature validation policy rules are fully processable to allow
the validation of electronic signatures issued under that form of
signature policy. They are described in the rest of this clause.
The signPolExtensions is a generic way to extend the definition of any
sub-component of a signature policy.
3.2 Signature Validation Policy
The signature validation policy defines for the signer which data
elements must be present in the electronic signature he provides and
for the verifier which data elements must be present under that
signature policy for an electronic signature to be potentially valid.
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The signature validation policy is described as follows:
SignatureValidationPolicy ::= SEQUENCE {
signingPeriod SigningPeriod,
commonRules CommonRules,
commitmentRules CommitmentRules,
signPolExtensions SignPolExtensions OPTIONAL
}
The signingPeriod identifies the date and time before which the
signature policy SHOULD NOT be used for creating signatures, and an
optional date after which it should not be used for creating
signatures.
SigningPeriod ::= SEQUENCE {
notBefore GeneralizedTime,
notAfter GeneralizedTime OPTIONAL }
3.3 Common Rules
The CommonRules define rules that are common to all commitment types.
These rules are defined in terms of trust conditions for certificates,
timestamps and attributes, along with any constraints on attributes
that may be included in the electronic signature.
CommonRules ::= SEQUENCE {
signerAndVeriferRules [0] SignerAndVerifierRules
OPTIONAL,
signingCertTrustCondition [1] SigningCertTrustCondition
OPTIONAL,
timeStampTrustCondition [2] TimestampTrustCondition
OPTIONAL,
attributeTrustCondition [3] AttributeTrustCondition
OPTIONAL,
algorithmConstraintSet [4] AlgorithmConstraintSet
OPTIONAL,
signPolExtensions [5] SignPolExtensions
OPTIONAL
}
If a field is present in CommonRules then the equivalent field must
not be present in any of the CommitmentRules (see below). If any of the
following fields are not present in CommonRules then it must be
present in each CommitmentRule:
* signerAndVeriferRules;
* signingCertTrustCondition;
* timeStampTrustCondition.
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3.4 Commitment Rules
The CommitmentRules consists of the validation rules which apply to
given commitment types:
CommitmentRules ::= SEQUENCE OF CommitmentRule
The CommitmentRule for given commitment types are defined in terms of
trust conditions for certificates, timestamps and attributes, along
with any constraints on attributes that may be included in the
electronic signature.
CommitmentRule ::= SEQUENCE {
selCommitmentTypes SelectedCommitmentTypes,
signerAndVeriferRules [0] SignerAndVerifierRules
OPTIONAL,
signingCertTrustCondition [1] SigningCertTrustCondition
OPTIONAL,
timeStampTrustCondition [2] TimestampTrustCondition
OPTIONAL,
attributeTrustCondition [3] AttributeTrustCondition
OPTIONAL,
algorithmConstraintSet [4] AlgorithmConstraintSet
OPTIONAL,
signPolExtensions [5] SignPolExtensions
OPTIONAL
}
SelectedCommitmentTypes ::= SEQUENCE OF CHOICE {
empty NULL,
recognizedCommitmentType CommitmentType }
If the SelectedCommitmentTypes indicates "empty" then this rule applied
when a commitment type is not present (i.e. the type of commitment is
indicated in the semantics of the message). Otherwise, the electronic
signature must contain a commitment type indication that must fit one
of the commitments types that are mentioned in CommitmentType.
A specific commitment type identifier must not appear in more than one
commitment rule.
CommitmentType ::= SEQUENCE {
identifier CommitmentTypeIdentifier,
fieldOfApplication [0] FieldOfApplication OPTIONAL,
semantics [1] DirectoryString OPTIONAL }
The fieldOfApplication and semantics fields define the specific use and
meaning of the commitment within the overall field of application
defined for the policy.
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3.5 Signer and Verifier Rules
The following rules apply to the format of electronic signatures defined using
[ES-FORMATS].
The SignerAndVerifierRules consists of signer rule and verification
rules as defined below:
SignerAndVerifierRules ::= SEQUENCE {
signerRules SignerRules,
verifierRules VerifierRules }
3.5.1 Signer Rules
The signer rules identify:
* if the eContent is empty and the signature is calculated using
a hash of signed data external to CMS structure.
* the CMS signed attributes that must be provided by the signer
under this policy;
* the CMS unsigned attribute that must be provided by the signer
under this policy;
* whether the certificate identifiers from the full certification
path up to the trust point must be provided by the signer in
the SigningCertificate attribute;
* whether a signer's certificate, or all certificates in the
certification path to the trust point must be provided by the
signer in the certificates field of SignedData.
SignerRules ::= SEQUENCE {
externalSignedData BOOLEAN OPTIONAL,
-- True if signed data is external to CMS structure
-- False if signed data part of CMS structure
-- not present if either allowed
mandatedSignedAttr CMSAttrs,
-- Mandated CMS signed attributes
mandatedUnsignedAttr CMSAttrs,
-- Mandated CMS unsigned attributed
mandatedCertificateRef [0] CertRefReq DEFAULT signerOnly,
-- Mandated Certificate Reference
mandatedCertificateInfo [1] CertInfoReq DEFAULT none,
-- Mandated Certificate Info
signPolExtensions [2] SignPolExtensions OPTIONAL
}
CMSAttrs ::= SEQUENCE OF OBJECT IDENTIFIER
The mandatedSignedAttr field must include the object identifier for
all those signed attributes required by this document as well as
additional attributes required by this policy.
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The mandatedUnsignedAttr field must include the object identifier for
all those unsigned attributes required by this document as well as
additional attributes required this policy. For example, if a signature
timestamp (see clause 1.1) is required by the signer the object
identifier for this attribute must be included.
The mandatedCertificateRef identifies whether just the signer's
certificate, or all the full certificate path must be provided by the
signer.
CertRefReq ::= ENUMERATED {
signerOnly (1),
-- Only reference to signer cert mandated
fullPath (2)
-- References for full cert path up to a trust point required
}
The mandatedCertificateInfo field identifies whether a signer's
certificate, or all certificates in the certification path to the trust
point must be provided by the signer in the certificates field of
SignedData.
CertInfoReq ::= ENUMERATED {
none (0) ,
-- No mandatory requirements
signerOnly (1) ,
-- Only reference to signer cert mandated
fullPath (2)
-- References for full cert path up to a
-- trust point mandated
}
3.5.2 Verifier Rules
The verifier rules identify:
* The CMS unsigned attributes that must be present under this policy
and must be added by the verifier if not added by the signer.
VerifierRules ::= SEQUENCE {
mandatedUnsignedAttr MandatedUnsignedAttr,
signPolExtensions SignPolExtensions OPTIONAL
}
MandatedUnsignedAttr ::= CMSAttrs
-- Mandated CMS unsigned attributed
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3.6 Certificate and Revocation Requirement
The SigningCertTrustCondition, TimestampTrustCondition and
AttributeTrustCondition (defined in subsequent sub-clauses) make use of
two ASN1 structures which are defined below: CertificateTrustTrees and
CertRevReq.
3.6.1 Certificate Requirements
The certificateTrustTrees identifies a set of self signed certificates
for the trust points used to start (or end) certificate path processing
and the initial conditions for certificate path validation as defined
RFC 2459 [7] section 4. This ASN1 structure is used to define policy
for validating the signing certificate, the TSA's certificate and
attribute certificates.
CertificateTrustTrees ::= SEQUENCE OF CertificateTrustPoint
CertificateTrustPoint ::= SEQUENCE {
trustpoint Certificate,
-- self-signed certificate
pathLenConstraint [0] PathLenConstraint OPTIONAL,
acceptablePolicySet [1] AcceptablePolicySet OPTIONAL,
-- If not present "any policy"
nameConstraints [2] NameConstraints OPTIONAL,
policyConstraints [3] PolicyConstraints OPTIONAL }
The trustPoint field gives the self signed certificate for the CA that
is used as the trust point for the start of certificate path
processing.
The pathLenConstraint field gives the maximum number of CA certificates
that may be in a certification path following the trustpoint. A value
of zero indicates that only the given trustpoint certificate and an
end-entity certificate may be used. If present, the pathLenConstraint
field must be greater than or equal to zero. Where pathLenConstraint
is not present, there is no limit to the allowed length of the
certification path.
PathLenConstraint ::= INTEGER (0..MAX)
The acceptablePolicySet field identifies the initial set of certificate
policies, any of which are acceptable under the signature policy.
AcceptablePolicySet ::= SEQUENCE OF CertPolicyId
CertPolicyId ::= OBJECT IDENTIFIER
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The nameConstraints field indicates a name space within which all
subject names in subsequent certificates in a certification path must
be located. Restrictions may apply to the subject distinguished name or
subject alternative names. Restrictions apply only when the specified
name form is present. If no name of the type is in the certificate, the
certificate is acceptable.
Restrictions are defined in terms of permitted or excluded name
subtrees. Any name matching a restriction in the excludedSubtrees field
is invalid regardless of information appearing in the ermittedSubtrees.
NameConstraints ::= SEQUENCE {
permittedSubtrees [0] GeneralSubtrees OPTIONAL,
excludedSubtrees [1] GeneralSubtrees OPTIONAL }
GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree
GeneralSubtree ::= SEQUENCE {
base GeneralName,
minimum [0] BaseDistance DEFAULT 0,
maximum [1] BaseDistance OPTIONAL }
BaseDistance ::= INTEGER (0..MAX)
The policyConstraints extension constrains path processing in two ways.
It can be used to prohibit policy mapping or require that each
certificate in a path contain an acceptable policy identifier.
The policyConstraints field, if present specifies requirement for
explicit indication of the certificate policy and/or the constraints on
policy mapping.
PolicyConstraints ::= SEQUENCE {
requireExplicitPolicy [0] SkipCerts OPTIONAL,
inhibitPolicyMapping [1] SkipCerts OPTIONAL }
SkipCerts ::= INTEGER (0..MAX)
If the inhibitPolicyMapping field is present, the value indicates the
number of additional certificates that may appear in the path
(including the trustpoint's self certificate) before policy mapping is
no longer permitted. For example, a value of one indicates that policy
mapping may be processed in certificates issued by the subject of this
certificate, but not in additional certificates in the path.
If the requireExplicitPolicy field is present, subsequent certificates
must include an acceptable policy identifier. The value of
requireExplicitPolicy indicates the number of additional certificates
that may appear in the path (including the trustpoint's self
certificate) before an explicit policy is required. An acceptable
policy identifier is the identifier of a policy required by the user of
the certification path or the identifier of a policy which has been
declared equivalent through policy mapping.
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3.6.2 Revocation Requirements
The RevocRequirements field specifies minimum requirements for
revocation information, obtained through CRLs and/or OCSP responses, to
be used in checking the revocation status of certificates. This ASN1
structure is used to define policy for validating the signing
certificate, the TSA's certificate and attribute certificates.
CertRevReq ::= SEQUENCE {
endCertRevReq RevReq,
caCerts [0] RevReq
}
Certificate revocation requirements are specified in terms of checks
required on:
* endCertRevReq: end certificates (i.e. the signers certificate,
the attribute certificate or the timestamping authority
certificate).
* caCerts: CA certificates.
RevReq ::= SEQUENCE {
enuRevReq EnuRevReq,
exRevReq SignPolExtensions OPTIONAL}
An authority certificate is certificate issued to an authority (e.g.
either to a certification authority or to an attribute authority (AA)).
A TimeStamping Authority (TSA) is a trusted third party that creates
time stamp tokens in order to indicate that a datum existed at a
particular point in time. See [TSP]
EnuRevReq ::= ENUMERATED {
clrCheck (0),
--Checks must be made against current CRLs
-- (or authority revocation lists (ARL))
ocspCheck (1), -- The revocation status must be checked
-- using the Online Certificate Status Protocol
-- (OCSP),RFC 2450.
bothCheck (2),
-- Both CRL and OCSP checks must be carried out
eitherCheck (3),
-- At least one of CRL or OCSP checks must be
-- carried out
noCheck (4),
-- no check is mandated
other (5)
-- Other mechanism as defined by signature policy
-- extension
}
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Revocation requirements are specified in terms of:
* clrCheck: Checks must be made against current CRLs (or
authority revocation lists);
* ocspCheck: The revocation status must be checked using the
Online Certificate Status Protocol (RFC 2450);
* bothCheck: Both OCSP and CRL checks must be carried out;
* eitherCheck: Either OCSP or CRL checks must be carried out;
* noCheck: No check is mandated.
3.7 Signing Certificate Trust Conditions
The SigningCertTrustCondition field identifies trust conditions for
certificate path processing used to validate the signing certificate.
SigningCertTrustCondition ::= SEQUENCE {
signerTrustTrees CertificateTrustTrees,
signerRevReq CertRevReq
}
3.8 TimeStamp Trust Conditions
The TimeStampTrustCondition field identifies trust conditions for
certificate path processing used to authenticate the timstamping
authority and constraints on the name of the timestamping authority.
This applies to the timestamp that must be present in every ES-T.
TimestampTrustCondition ::= SEQUENCE {
ttsCertificateTrustTrees [0] CertificateTrustTrees
OPTIONAL,
ttsRevReq [1] CertRevReq
OPTIONAL,
ttsNameConstraints [2] NameConstraints
OPTIONAL,
cautionPeriod [3] DeltaTime
OPTIONAL,
signatureTimestampDelay [4] DeltaTime
OPTIONAL }
DeltaTime ::= SEQUENCE {
deltaSeconds INTEGER,
deltaMinutes INTEGER,
deltaHours INTEGER,
deltaDays INTEGER }
If ttsCertificateTrustTrees is not present then the same rule as
defined in certificateTrustCondition applies to certification of the
timestamping authorities public key.
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The tstrRevReq specifies minimum requirements for revocation
information, obtained through CRLs and/or OCSP responses, to be used in
checking the revocation status of the time stamp that must be present
in the ES-T.
If ttsNameConstraints is not present then there are no additional
naming constraints on the trusted timestamping authority other than
those implied by the ttsCertificateTrustTrees.
The cautionPeriod field specifies a caution period after the signing
time that it is mandated the verifier must wait to get high assurance
of the validity of the signer's key and that any relevant revocation
has been notified. The revocation status information forming the ES
with Complete validation data must not be collected and used to
validate the electronic signature until after this caution period.
The signatureTimestampDelay field specifies a maximum acceptable time
between the signing time and the time at which the signature timestamp,
as used to form the ES Timestamped, is created for the verifier. If the
signature timestamp is later that the time in the signing-time
attribute by more than the value given in signatureTimestampDelay, the
signature must be considered invalid.
3.9 Attribute Trust Conditions
If the attributeTrustCondition field is not present then any certified
attributes may not considered to be valid under this validation policy.
The AttributeTrustCondition field is defined as follows:
AttributeTrustCondition ::= SEQUENCE {
attributeMandated BOOLEAN,
-- Attribute must be present
howCertAttribute HowCertAttribute,
attrCertificateTrustTrees [0] CertificateTrustTrees OPTIONAL,
attrRevReq [1] CertRevReq OPTIONAL,
attributeConstraints [2] AttributeConstraints OPTIONAL }
If attributeMandated is true then an attribute, certified within the
following constraints, must be present. If false, then the signature
is still valid if no attribute is specified.
The howCertAttribute field specifies whether attributes uncertified
attributes "claimed" by the signer, or certified attributes
(i.e. Attribute Certificates) or either using the signer
attributes attribute defined in [ES-FORMATS] section 3.12.3.
HowCertAttribute ::= ENUMERATED {
claimedAttribute (0),
certifiedAttribtes (1),
either (2) }
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The attrCertificateTrustTrees specifies certificate path conditions for
any attribute certificate. If not present the same rules apply as in
certificateTrustCondition.
The attrRevReq specifies minimum requirements for revocation
information, obtained through CRLs and/or OCSP responses, to be used in
checking the revocation status of Attribute Certificates, if any are
present.
If the attributeConstraints field is not present then there are no
constraints on the attributes that may be validated under this policy.
The attributeConstraints field is defined as follows:
AttributeConstraints ::= SEQUENCE {
attributeTypeConstarints [0] AttributeTypeConstraints
OPTIONAL,
attributeValueConstarints [1] AttributeValueConstraints
OPTIONAL }
If present, the attributeTypeConstarints field specifies the attribute
types which are considered valid under the signature policy. Any value
for that attribute is considered valid.
AttributeTypeConstraints ::= SEQUENCE OF AttributeType
If present, the attributeTypeConstraints field specifies the specific
attribute values which are considered valid under the signature policy.
AttributeValueConstraints ::= SEQUENCE OF AttributeTypeAndValue
3.10 Algorithm Constraints
The algorithmConstrains fields, if present, identifies the signing
algorithms (hash, public key cryptography, combined hash and public key
cryptography) that may be used for specific purposes and any minimum
length. If this field is not present then the policy applies no
constraints.
AlgorithmConstraintSet ::= SEQUENCE { -- Algorithm constrains on:
signerAlgorithmConstraints [0] AlgorithmConstraints OPTIONAL,
-- signer
eeCertAlgorithmConstraints [1] AlgorithmConstraints OPTIONAL,
-- issuer of end entity certs.
caCertAlgorithmConstraints [2] AlgorithmConstraints OPTIONAL,
-- issuer of CA certificates
aaCertAlgorithmConstraints [3] AlgorithmConstraints OPTIONAL,
-- Attribute Authority
tsaCertAlgorithmConstraints [4] AlgorithmConstraints OPTIONAL
-- TimeStamping Authority
}
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AlgorithmConstraints ::= SEQUENCE OF AlgAndLength
AlgAndLength ::= SEQUENCE {
algID OBJECT IDENTIFIER,
minKeyLength INTEGER OPTIONAL,
-- Minimum key length in bits
other SignPolExtensions OPTIONAL
}
An Attribute Authority (AA)is authority which assigns privileges by
issuing attribute certificates
3.11 Signature Policy Extensions
Additional signature policy rules may be added to:
* the overall signature policy structure, as defined in
clause 3.1;
* the signature validation policy structure, as defined in
clause 3.2;
* the common rules, as defined in clause 3.3;
* the commitment rules, as defined in clause 3.4;
* the signer rules, as defined in clause 3.5.1;
* the verifier rules, as defined in clause 3.5.2;
* the revocation requirements in clause 3.6.2;
* the algorithm constraints in clause 3.10.
These extensions to the signature policy rules must be defined using
an ASN.1 syntax with an associated object identifier carried in the
SignPolExtn as defined below:
SignPolExtensions ::= SEQUENCE OF SignPolExtn
SignPolExtn ::= SEQUENCE {
extnID OBJECT IDENTIFIER,
extnValue OCTET STRING }
The extnID field must contain the object identifier for the extension.
The extnValue field must contain the DER (see ITU-T Recommendation
X.690 [4]) encoded value of the extension. The definition of an
extension, as identified by extnID must include a definition of the
syntax and semantics of the extension.
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 17]
Internet Draft Electronic Signature Policies
4. Security considerations
To be defined
5. Conformance Requirements
To be defined
6. References
[ES201733] ETSI Standard ES 201 733 V1.1.3 (2000-05) Electronic
Signature Formats. Note: copies of ETSI ES 201 733 can be freely download
from the ETSI web site www.etsi.org.
[ES-FORMATS] ETSI TC-SEC, D.Pinkas, J.Ross, N.Pope. Electronic Signature
formats for long term electronic signatures <draft-ietf-smime-esformats>
To be published as an INFORMATIONAL RFC.
[TSP] C. Adams, D. Pinkas, R. Zuccherato, P. Cain. Time Stamp Protocol <draft-
ietf-pkix-tsp>.
[OCSP] M. Myers, R. Ankney, A. Malpani, S. Galperin, C. Adams.
On-line Status Certificate Protocol, RFC 2560.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[ESS] P. Hoffman, "Enhanced Security Services for S/MIME", RFC 2634
June 1999
[CMS] R. Housley, "Cryptographic Message Syntax", RFC 2630, RFC 2630,
June 1999.
[RFC2459] R. Housley, W. Ford, W. Polk, D. Solo, "Internet X.509 Public
Key Infrastructure, Certificate and CRL Profile," RFC 2459, January
1999.
[PKCS9] RSA Laboratories, "The Public-Key Cryptography Standards
(PKCS)", RSA Data Security Inc., Redwood City, California, November
1993 Release.
[ISONR] ISO/IEC 10181-5: Security Frameworks in Open Systems.
Non-Repudiation Framework. April 1997.
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 18]
Internet Draft Electronic Signature Policies
7. Authors' Addresses
This Experimental RFC has been produced in ETSI TC-SEC.
ETSI
F-06921 Sophia Antipolis, Cedex - FRANCE
650 Route des Lucioles - Sophia Antipolis
Valbonne - FranceTel: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16
secretariat@etsi.fr
http://www.etsi.org
Contact Point
Harri Rasilainen
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex
FRANCE
harri.rasilainen@etsi.fr
John Ross
Security & Standards
192 Moulsham Street
Chelmsford, Essex
CM2 0LG
United Kingdom
ross@secstan.com
Denis Pinkas Nick Pope
Bull S.A. Security & Standards
12, rue de Paris 192 Moulsham Street
B.P. 59 Chelmsford, Essex
78231 Le Pecq CM2 0LG
FRANCE United Kingdom
pinkas.denis@bull.net pope@secstan.com
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 19]
Internet Draft Electronic Signature Policies
8. Full Copyright Statement
Copyright (C) The Internet Society (2000). All Rights Reserved.
This document and translations of it may be copied and furnished to
others,and derivative works that comment on or otherwise explain it or
assist in its implementation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are included
on all such copies and derivative works. However, this document itself may
not be modified in any way, such as by removing the copyright notice or
references to the Internet Society or other Internet organizations, except
as needed for the purpose ofdeveloping Internet standards in which case
the procedures for copyrights defined in the Internet Standards process
must be followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be revoked
by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL
NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE.
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 20]
Internet Draft Electronic Signature Policies
Annex A (normative):
ASN.1 Definitions
This annex provides the reference definition of the ASN.1 syntax
signature policies definitions for new syntax defined in this document.
A.1 Definitions Using X.208 (1988) ASN.1 Syntax
NOTE: The ASN.1 Module defined in clause A.1 has precedence over that defined in
Annex A-2 in the case of any conflict.
ETS-ElectronicSignaturePolicies-88syntax { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-mod(0) 7}
DEFINITIONS EXPLICIT TAGS ::=
BEGIN
-- EXPORTS All
IMPORTS
-- Internet X.509 Public Key Infrastructure
- Certificate and CRL Profile: RFC 2459
Certificate, AlgorithmIdentifier, CertificateList, Name,
GeneralNames, GeneralName, DirectoryString,Attribute,
AttributeTypeAndValue, AttributeType, AttributeValue,
PolicyInformation, BMPString, UTF8String
FROM PKIX1Explicit88
{iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-pkix1-explicit-88(1)}
;
-- Signature Policy Specification
-- ==============================
SignaturePolicy ::= SEQUENCE {
signPolicyHashAlg AlgorithmIdentifier,
signPolicyInfo SignPolicyInfo,
signPolicyHash SignPolicyHash OPTIONAL }
SignPolicyHash ::= OCTET STRING
SignPolicyInfo ::= SEQUENCE {
signPolicyIdentifier SignPolicyId,
dateOfIssue GeneralizedTime,
policyIssuerName PolicyIssuerName,
fieldOfApplication FieldOfApplication,
signatureValidationPolicy SignatureValidationPolicy,
signPolExtensions SignPolExtensions
OPTIONAL
}
SignPolicyId ::= OBJECT IDENTIFIER
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 21]
Internet Draft Electronic Signature Policies
PolicyIssuerName ::= GeneralNames
FieldOfApplication ::= DirectoryString
SignatureValidationPolicy ::= SEQUENCE {
signingPeriod SigningPeriod,
commonRules CommonRules,
commitmentRules CommitmentRules,
signPolExtensions SignPolExtensions
OPTIONAL
}
SigningPeriod ::= SEQUENCE {
notBefore GeneralizedTime,
notAfter GeneralizedTime OPTIONAL }
CommonRules ::= SEQUENCE {
signerAndVeriferRules [0] SignerAndVerifierRules
OPTIONAL,
signingCertTrustCondition [1] SigningCertTrustCondition
OPTIONAL,
timeStampTrustCondition [2] TimestampTrustCondition
OPTIONAL,
attributeTrustCondition [3] AttributeTrustCondition
OPTIONAL,
algorithmConstraintSet [4] AlgorithmConstraintSet
OPTIONAL,
signPolExtensions [5] SignPolExtensions
OPTIONAL
}
CommitmentRules ::= SEQUENCE OF CommitmentRule
CommitmentRule ::= SEQUENCE {
selCommitmentTypes SelectedCommitmentTypes,
signerAndVeriferRules [0] SignerAndVerifierRules
OPTIONAL,
signingCertTrustCondition [1] SigningCertTrustCondition
OPTIONAL,
timeStampTrustCondition [2] TimestampTrustCondition
OPTIONAL,
attributeTrustCondition [3] AttributeTrustCondition
OPTIONAL,
algorithmConstraintSet [4] AlgorithmConstraintSet
OPTIONAL,
signPolExtensions [5] SignPolExtensions
OPTIONAL
}
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 22]
Internet Draft Electronic Signature Policies
SelectedCommitmentTypes ::= SEQUENCE OF CHOICE {
empty NULL,
recognizedCommitmentType CommitmentType }
CommitmentType ::= SEQUENCE {
identifier CommitmentTypeIdentifier,
fieldOfApplication [0] FieldOfApplication OPTIONAL,
semantics [1] DirectoryString OPTIONAL }
SignerAndVerifierRules ::= SEQUENCE {
signerRules SignerRules,
verifierRules VerifierRules }
SignerRules ::= SEQUENCE {
externalSignedData BOOLEAN OPTIONAL,
-- True if signed data is external to CMS structure
-- False if signed data part of CMS structure
-- not present if either allowed
mandatedSignedAttr CMSAttrs,
-- Mandated CMS signed attributes
mandatedUnsignedAttr CMSAttrs,
-- Mandated CMS unsigned attributed
mandatedCertificateRef [0] CertRefReq DEFAULT signerOnly,
-- Mandated Certificate Reference
mandatedCertificateInfo [1] CertInfoReq DEFAULT none,
-- Mandated Certificate Info
signPolExtensions [2] SignPolExtensions
OPTIONAL}
CMSAttrs ::= SEQUENCE OF OBJECT IDENTIFIER
CertRefReq ::= ENUMERATED {
signerOnly (1),
-- Only reference to signer cert mandated
fullPath (2)
-- References for full cert path up to a trust point required
}
CertInfoReq ::= ENUMERATED {
none (0),
-- No mandatory requirements
signerOnly (1),
-- Only reference to signer cert mandated
fullPath (2)
-- References for full cert path up to a trust point mandated
}
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 23]
Internet Draft Electronic Signature Policies
VerifierRules ::= SEQUENCE {
mandatedUnsignedAttr MandatedUnsignedAttr,
signPolExtensions SignPolExtensions OPTIONAL
}
MandatedUnsignedAttr ::= CMSAttrs
-- Mandated CMS unsigned attributed
CertificateTrustTrees ::= SEQUENCE OF CertificateTrustPoint
CertificateTrustPoint ::= SEQUENCE {
trustpoint Certificate,
-- self-signed certificate
pathLenConstraint [0] PathLenConstraint OPTIONAL,
acceptablePolicySet [1] AcceptablePolicySet OPTIONAL,
-- If not present "any policy"
nameConstraints [2] NameConstraints OPTIONAL,
policyConstraints [3] PolicyConstraints OPTIONAL }
PathLenConstraint ::= INTEGER (0..MAX)
AcceptablePolicySet ::= SEQUENCE OF CertPolicyId
CertPolicyId ::= OBJECT IDENTIFIER
NameConstraints ::= SEQUENCE {
permittedSubtrees [0] GeneralSubtrees OPTIONAL,
excludedSubtrees [1] GeneralSubtrees OPTIONAL }
GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree
GeneralSubtree ::= SEQUENCE {
base GeneralName,
minimum [0] BaseDistance DEFAULT 0,
maximum [1] BaseDistance OPTIONAL }
BaseDistance ::= INTEGER (0..MAX)
PolicyConstraints ::= SEQUENCE {
requireExplicitPolicy [0] SkipCerts OPTIONAL,
inhibitPolicyMapping [1] SkipCerts OPTIONAL }
SkipCerts ::= INTEGER (0..MAX)
CertRevReq ::= SEQUENCE {
endCertRevReq RevReq,
caCerts [0] RevReq
}
RevReq ::= SEQUENCE {
enuRevReq EnuRevReq,
exRevReq SignPolExtensions OPTIONAL}
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 24]
Internet Draft Electronic Signature Policies
EnuRevReq ::= ENUMERATED {
clrCheck (0), --Checks must be made against current CRLs
-- (or authority revocation lists)
ocspCheck (1), -- The revocation status must be checked
-- using the Online Certificate Status Protocol (RFC 2450)
bothCheck (2),
-- Both CRL and OCSP checks must be carried out
eitherCheck (3),
-- At least one of CRL or OCSP checks must be carried out
noCheck (4),
-- no check is mandated
other (5)
-- Other mechanism as defined by signature policy extension
}
SigningCertTrustCondition ::= SEQUENCE {
signerTrustTrees CertificateTrustTrees,
signerRevReq CertRevReq
}
TimestampTrustCondition ::= SEQUENCE {
ttsCertificateTrustTrees [0] CertificateTrustTrees
OPTIONAL,
ttsRevReq [1] CertRevReq
OPTIONAL,
ttsNameConstraints [2] NameConstraints
OPTIONAL,
cautionPeriod [3] DeltaTime
OPTIONAL,
signatureTimestampDelay [4] DeltaTime
OPTIONAL }
DeltaTime ::= SEQUENCE {
deltaSeconds INTEGER,
deltaMinutes INTEGER,
deltaHours INTEGER,
deltaDays INTEGER }
AttributeTrustCondition ::= SEQUENCE {
attributeMandated BOOLEAN,
-- Attribute must be present
howCertAttribute HowCertAttribute,
attrCertificateTrustTrees [0] CertificateTrustTrees OPTIONAL,
attrRevReq [1] CertRevReq OPTIONAL,
attributeConstraints [2] AttributeConstraints OPTIONAL }
HowCertAttribute ::= ENUMERATED {
claimedAttribute (0),
certifiedAttribtes (1),
either (2) }
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 25]
Internet Draft Electronic Signature Policies
AttributeConstraints ::= SEQUENCE {
attributeTypeConstarints [0] AttributeTypeConstraints
OPTIONAL,
attributeValueConstarints [1] AttributeValueConstraints
OPTIONAL }
AttributeTypeConstraints ::= SEQUENCE OF AttributeType
AttributeValueConstraints ::= SEQUENCE OF AttributeTypeAndValue
AlgorithmConstraintSet ::= SEQUENCE { -- Algorithm constrains on:
signerAlgorithmConstraints [0] AlgorithmConstraints OPTIONAL,
-- signer
eeCertAlgorithmConstraints [1] AlgorithmConstraints OPTIONAL,
-- issuer of end entity certs.
caCertAlgorithmConstraints [2] AlgorithmConstraints OPTIONAL,
-- issuer of CA certificates
aaCertAlgorithmConstraints [3] AlgorithmConstraints OPTIONAL,
-- Attribute Authority
tsaCertAlgorithmConstraints [4] AlgorithmConstraints OPTIONAL
-- TimeStamping Authority
}
AlgorithmConstraints ::= SEQUENCE OF AlgAndLength
AlgAndLength ::= SEQUENCE {
algID OBJECT IDENTIFIER,
minKeyLength INTEGER OPTIONAL,
-- Minimum key length in bits other
SignPolExtensions OPTIONAL
}
SignPolExtensions ::= SEQUENCE OF SignPolExtn
SignPolExtn ::= SEQUENCE {
extnID OBJECT IDENTIFIER,
extnValue OCTET STRING }
END -- ETS-ElectronicSignaturePolicies-88syntax --
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 26]
Internet Draft Electronic Signature Policies
A.2 Definitions Using X.680 1997 ASN.1 Syntax
NOTE: The ASN.1 module defined in clause A.1 has precedence over that
defined in clause A.2 in the case of any conflict.
ETS-ElectronicSignaturePolicies-97Syntax { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-mod(0) 8}
DEFINITIONS EXPLICIT TAGS ::=
BEGIN
-- EXPORTS All -
IMPORTS
-- Internet X.509 Public Key Infrastructure
-- Certificate and CRL Profile: RFC 2459
Certificate, AlgorithmIdentifier, CertificateList, Name,
GeneralNames, GeneralName, DirectoryString, Attribute,
AttributeTypeAndValue, AttributeType, AttributeValue,
PolicyInformation
FROM PKIX1Explicit93
{iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-explicit-88(1)}
;
-- S/MIME Object Identifier arcs used in the present document
-- ==================================================================
-- S/MIME OID arc used in the present document
-- id-smime OBJECT IDENTIFIER ::= { iso(1) member-body(2)
-- us(840) rsadsi(113549) pkcs(1) pkcs-9(9) 16 }
-- S/MIME Arcs
-- id-mod OBJECT IDENTIFIER ::= { id-smime 0 }
-- modules
-- id-ct OBJECT IDENTIFIER ::= { id-smime 1 }
-- content types
-- id-aa OBJECT IDENTIFIER ::= { id-smime 2 }
-- attributes
-- id-spq OBJECT IDENTIFIER ::= { id-smime 5 }
-- signature policy qualifier
-- id-cti OBJECT IDENTIFIER ::= { id-smime 6 }
-- commitment type identifier
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 27]
Internet Draft Electronic Signature Policies
-- Signature Policy Specification
-- ==============================
SignaturePolicy ::= SEQUENCE {
signPolicyHashAlg AlgorithmIdentifier,
signPolicyInfo SignPolicyInfo,
signPolicyHash SignPolicyHash OPTIONAL }
SignPolicyHash ::= OCTET STRING
SignPolicyInfo ::= SEQUENCE {
signPolicyIdentifier SignPolicyId,
dateOfIssue GeneralizedTime,
policyIssuerName PolicyIssuerName,
fieldOfApplication FieldOfApplication,
signatureValidationPolicy SignatureValidationPolicy,
signPolExtensions SignPolExtensions
OPTIONAL
}
SignPolicyId ::= OBJECT IDENTIFIER
PolicyIssuerName ::= GeneralNames
FieldOfApplication ::= DirectoryString
SignatureValidationPolicy ::= SEQUENCE {
signingPeriod SigningPeriod,
commonRules CommonRules,
commitmentRules CommitmentRules,
signPolExtensions SignPolExtensions OPTIONAL
}
SigningPeriod ::= SEQUENCE {
notBefore GeneralizedTime,
notAfter GeneralizedTime OPTIONAL }
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 28]
Internet Draft Electronic Signature Policies
CommonRules ::= SEQUENCE {
signerAndVeriferRules [0] SignerAndVerifierRules
OPTIONAL,
signingCertTrustCondition [1] SigningCertTrustCondition
OPTIONAL,
timeStampTrustCondition [2] TimestampTrustCondition
OPTIONAL,
attributeTrustCondition [3] AttributeTrustCondition
OPTIONAL,
algorithmConstraintSet [4] AlgorithmConstraintSet
OPTIONAL,
signPolExtensions [5] SignPolExtensions
OPTIONAL
}
CommitmentRules ::= SEQUENCE OF CommitmentRule
CommitmentRule ::= SEQUENCE {
selCommitmentTypes SelectedCommitmentTypes,
signerAndVeriferRules [0] SignerAndVerifierRules
OPTIONAL,
signingCertTrustCondition [1] SigningCertTrustCondition
OPTIONAL,
timeStampTrustCondition [2] TimestampTrustCondition
OPTIONAL,
attributeTrustCondition [3] AttributeTrustCondition
OPTIONAL,
algorithmConstraintSet [4] AlgorithmConstraintSet
OPTIONAL,
signPolExtensions [5] SignPolExtensions
OPTIONAL
}
SelectedCommitmentTypes ::= SEQUENCE OF CHOICE {
empty NULL,
recognizedCommitmentType CommitmentType }
CommitmentType ::= SEQUENCE {
identifier CommitmentTypeIdentifier,
fieldOfApplication [0] FieldOfApplication OPTIONAL,
semantics [1] DirectoryString OPTIONAL }
SignerAndVerifierRules ::= SEQUENCE {
signerRules SignerRules,
verifierRules VerifierRules }
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 29]
Internet Draft Electronic Signature Policies
SignerRules ::= SEQUENCE {
externalSignedData BOOLEAN OPTIONAL,
-- True if signed data is external to CMS structure
-- False if signed data part of CMS structure
-- not present if either allowed
mandatedSignedAttr CMSAttrs,
-- Mandated CMS signed attributes
mandatedUnsignedAttr CMSAttrs,
-- Mandated CMS unsigned attributed
mandatedCertificateRef [0] CertRefReq DEFAULT signerOnly,
-- Mandated Certificate Reference
mandatedCertificateInfo [1] CertInfoReq DEFAULT none,
-- Mandated Certificate Info
signPolExtensions [2] SignPolExtensions OPTIONAL
}
CMSAttrs ::= SEQUENCE OF OBJECT IDENTIFIER
CertRefReq ::= ENUMERATED {
signerOnly (1),
-- Only reference to signer cert mandated
fullPath (2)
-- References for full cert path up to a trust
-- point required
}
CertInfoReq ::= ENUMERATED {
none (0) ,
-- No mandatory requirements
signerOnly (1) ,
-- Only reference to signer cert mandated
fullPath (2)
-- References for full cert path up to a
-- trust point mandated
}
VerifierRules ::= SEQUENCE {
mandatedUnsignedAttr MandatedUnsignedAttr,
signPolExtensions SignPolExtensions OPTIONAL
}
MandatedUnsignedAttr ::= CMSAttrs
-- Mandated CMS unsigned attributed
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 30]
Internet Draft Electronic Signature Policies
CertificateTrustTrees ::= SEQUENCE OF CertificateTrustPoint
CertificateTrustPoint ::= SEQUENCE {
trustpoint Certificate,
-- self-signed certificate
pathLenConstraint [0] PathLenConstraint OPTIONAL,
acceptablePolicySet [1] AcceptablePolicySet OPTIONAL,
-- If not present "any policy"
nameConstraints [2] NameConstraints OPTIONAL,
policyConstraints [3] PolicyConstraints OPTIONAL }
PathLenConstraint ::= INTEGER (0..MAX)
AcceptablePolicySet ::= SEQUENCE OF CertPolicyId
CertPolicyId ::= OBJECT IDENTIFIER
NameConstraints ::= SEQUENCE {
permittedSubtrees [0] GeneralSubtrees OPTIONAL,
excludedSubtrees [1] GeneralSubtrees OPTIONAL }
GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree
GeneralSubtree ::= SEQUENCE {
base GeneralName,
minimum [0] BaseDistance DEFAULT 0,
maximum [1] BaseDistance OPTIONAL }
BaseDistance ::= INTEGER (0..MAX)
PolicyConstraints ::= SEQUENCE {
requireExplicitPolicy [0] SkipCerts OPTIONAL,
inhibitPolicyMapping [1] SkipCerts OPTIONAL }
SkipCerts ::= INTEGER (0..MAX)
CertRevReq ::= SEQUENCE {
endCertRevReq RevReq,
caCerts [0] RevReq
}
RevReq ::= SEQUENCE {
enuRevReq EnuRevReq,
exRevReq SignPolExtensions OPTIONAL}
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 31]
Internet Draft Electronic Signature Policies
EnuRevReq ::= ENUMERATED {
clrCheck (0),
-- Checks must be made against current CRLs
-- (or authority revocation lists)
ocspCheck (1),
-- The revocation status must be checked using
-- the Online Certificate Status Protocol (RFC 2450)
bothCheck (2),
-- Both CRL and OCSP checks must be carried out
eitherCheck (3),
-- At least one of CRL or OCSP checks must be carried out
noCheck (4),
-- no check is mandated
other (5)
-- Other mechanism as defined by signature policy
-- extension
}
SigningCertTrustCondition ::= SEQUENCE {
signerTrustTrees CertificateTrustTrees,
signerRevReq CertRevReq
}
TimestampTrustCondition ::= SEQUENCE {
ttsCertificateTrustTrees [0] CertificateTrustTrees
OPTIONAL,
ttsRevReq [1] CertRevReq
OPTIONAL,
ttsNameConstraints [2] NameConstraints
OPTIONAL,
cautionPeriod [3] DeltaTime
OPTIONAL,
signatureTimestampDelay [4] DeltaTime
OPTIONAL }
DeltaTime ::= SEQUENCE {
deltaSeconds INTEGER,
deltaMinutes INTEGER,
deltaHours INTEGER,
deltaDays INTEGER }
AttributeTrustCondition ::= SEQUENCE {
attributeMandated BOOLEAN,
-- Attribute must be present
howCertAttribute HowCertAttribute,
attrCertificateTrustTrees [0] CertificateTrustTrees OPTIONAL,
attrRevReq [1] CertRevReq OPTIONAL,
attributeConstraints [2] AttributeConstraints OPTIONAL }
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 32]
Internet Draft Electronic Signature Policies
HowCertAttribute ::= ENUMERATED {
claimedAttribute (0),
certifiedAttribtes (1),
either (2) }
AttributeConstraints ::= SEQUENCE {
attributeTypeConstarints [0] AttributeTypeConstraints
OPTIONAL,
attributeValueConstarints [1] AttributeValueConstraints
OPTIONAL }
AttributeTypeConstraints ::= SEQUENCE OF AttributeType
AttributeValueConstraints ::= SEQUENCE OF AttributeTypeAndValue
AlgorithmConstraintSet ::= SEQUENCE {
-- Algorithm constrains on:
signerAlgorithmConstraints [0] AlgorithmConstraints OPTIONAL,
-- signer
eeCertAlgorithmConstraints [1] AlgorithmConstraints OPTIONAL,
-- issuer of end entity certs.
caCertAlgorithmConstraints [2] AlgorithmConstraints OPTIONAL,
-- issuer of CA certificates
aaCertAlgorithmConstraints [3] AlgorithmConstraints OPTIONAL,
-- Attribute Authority
tsaCertAlgorithmConstraints [4] AlgorithmConstraints OPTIONAL
-- TimeStamping Authority
}
AlgorithmConstraints ::= SEQUENCE OF AlgAndLength
AlgAndLength ::= SEQUENCE {
algID OBJECT IDENTIFIER,
minKeyLength INTEGER OPTIONAL,
-- Minimum key length in bits
other SignPolExtensions OPTIONAL
}
SignPolExtensions ::= SEQUENCE OF SignPolExtn
SignPolExtn ::= SEQUENCE {
extnID OBJECT IDENTIFIER,
extnValue OCTET STRING }
END -- ETS-ElectronicPolicies-97Syntax
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 33]
Internet Draft Electronic Signature Policies
Annex B (informative):
B.1 Signature Policy and Signature Validation Policy
The definition of electronic signature mentions: "a commitment has been
explicitly endorsed under a "Signature Policy", at a given time, by a
signer under an identifier, e.g. a name or a pseudonym, and optionally
a role. "
Electronic signatures are commonly applied within the context of a
legal or contractual framework. This establishes the requirements on
the electronic signatures and any special semantics (e.g. agreement,
intent). These requirements may be defined in very general abstract
terms or in terms of detailed rules. The specific semantics associated
with an electronic signature implied by a legal or contractual
framework are outside the scope of this document.
If the signature policy is recognized, within the legal/contractual
context, as providing commitment, then the signer explicitly agrees
with terms and conditions which are implicitly or explicitly part of
the signed data.
When two independent parties want to evaluate an electronic signature,
it is fundamental that they get the same result. It is therefore
important that the conditions agreed by the signer at the time of
signing are indicated to the verifier and any arbitrator. An aspect
that enables this to be known by all parties is the signature policy.
The technical implications of the signature policy on the electronic
signature with all the validation data are called the "Signature
Validation Policy". The signature validation policy specifies
the rules used to validate the signature.
This document does not mandate the form and encoding of the
specification of the signature policy. However, for a given signature
policy there must be one definitive form that has a unique binary
encoded value.
This document includes, as an option, a formal structure for signature
validation policy based on the use of Abstract Syntax Notation 1
(ASN.1).
Given the specification of the signature policy and its hash value an
implementation of a verification process must obey the rules defined
in the specification.
This document places no restriction on how it should be implemented.
Provide the implementation conforms to the conformance requirements as
define in clause 5 implementation options include:
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 34]
Internet Draft Electronic Signature Policies
A validation process that supports a specific signature policy as
identified by the signature policy OID. Such an implementation should
conform to a human readable description provided all the processing
rules of the signature policy are clearly defined. However, if
additional policies need to be supported, then such an implementation
would need to be customized for each additional policy. This type of
implementation may be simpler to implement initially, but can be
difficult to enhance to support numerous additional signature policies.
A validation process that is dynamically programmable and able to adapt
its validation rules in accordance with a description of the signature
policy provided in a computer-processable language. This present
document defines such a policy using an ASN.1 structure (see 6.1). This
type of implementation could support multiple signature policies
without being modified every time, provided all the validation rules
specified as part of the signature policy are known by the
implementation. (i.e. only requires modification if there are
additional rules specified).
The precise content of a signature policy is not mandated by the
current document. However, a signature policy must be sufficiently
definitive to avoid any ambiguity as to its implementation
requirements. It must be absolutely clear under which conditions an
electronic signature should be accepted. For this reason, it should
contain the following information:
* General information about the signature policy which includes:
- a unique identifier of the policy;
- the name of the issuer of the policy;
- the date the policy was issued;
- the field of application of the policy.
* The signature verification policy which includes:
- the signing period,
- a list of recognized commitment types;
- rules for Use of Certification Authorities;
- rules for Use of Revocation Status Information;
- rules for Use of Roles;
- rules for use of Timestamping and Timing;
- signature verification data to be provided by the
signer/collected by verifier;
- any constraints on signature algorithms and key lengths.
* Other signature policy rules required to meet the objectives of
the signature.
Variations of the validation policy rules may apply to different
commitment types.
ETSI TC-SEC, Ross, Pinkas, Pope Experimental RFC [Page 35]
Internet Draft Electronic Signature Policies
B.2 Identification of Signature Policy
When data is signed the signer indicates the signature policy
applicable to that electronic signature by including an object
identifier for the signature policy with the signature. The signer and
verifier must apply the rules specified by the identified policy. In
addition to the identifier of the signature policy the signer must
include the hash of the signature policy, so it can be verified that
the policy selected by the signer is the identical to the one being
used the verifier.
A signature policy may be qualified by additional information. This can
includes:
* A URL where a copy of the Signature Policy may be obtained;
* A user notice that should be displayed when the signature is
verified;
If no signature policy is identified then the signature may be assumed
to have been generated/verified without any policy constraints, and
hence may be given no specific legal or contractual significance
through the context of a signature policy.
A "Signature Policy" will be identifiable by an OID (Object Identifier)
and verifiable using a hash of the signature policy.
B.3 General Signature Policy Information
General information should be recorded about the signature policy along
with the definition of the rules which form the signature policy as
described in subsequent subclauses. This should include:
* Policy Object Identifier: The "Signature Policy" will be
identifiable by an OID (Object Identifier) whose last component
(i.e. right most) is an integer that is specific to a particular
version issued on the given date.
* Date of issue: When the "Signature Policy" was issued.
* Signature Policy Issuer name: An identifier for the body
responsible for issuing the Signature Policy. This may be used
by the signer or verifying in deciding if a policy is to be
trusted, in which case the signer/verifier must authenticate
the origin of the signature policy as coming from the identified
issuer.
* Signing period: The start time and date, optionally with an end
time and date, for the period over which the signature policy
may be used to generate electronic signatures.
* Field of application: This defines in general terms the general
legal/contract/application contexts in which the signature
policy is to be used and the specific purposes for which the
electronic signature is to be applied.
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B.4 Recognized Commitment Types
The signature validation policy may recognize one or more types of
commitment as being supported by electronic signatures produced under
the security policy. If an electronic signature does not contain a
recognized commitment type then the semantics of the electronic
signature is dependent on the data being signed and the context in
which it is being used.
Only recognized commitment types are allowed in an electronic
signature.
The definition of a commitment type includes:
* the object identifier for the commitment;
* the contractual/legal/application context in which the signature
may be used (e.g. submission of messages);
* a description of the support provided within the terms of the
context (e.g. proof that the identified source submitted the
message if the signature is created when message submission is
initiated).
The definition of a commitment type can be registered:
* as part of the validation policy;
* as part of the application/contract/legal environment;
* as part of generic register of definitions.
The legal/contractual context will determine the rules applied to the
signature, as defined by the signature policy and its recognized
commitment types, make it fit for purpose intended.
B.5 Rules for Use of Certification Authorities
The certificate validation process of the verifier, and hence the
certificates that may be used by the signer for a valid electronic
signature, may be constrained by the combination of the trust point and
certificate path constraints in the signature validation policy.
B.5.1 Trust Points
The signature validation policy defines the certification authority
trust points that are to be used for signature verification. Several
trust points may be specified under one signature policy. Specific
trust points may be specified for a particular type of commitment
defined under the signature policy. For a signature to be valid a
certification path must exists between the Certification Authority
that has granted the certificate selected by the signer (i.e. the used
user-certificate) and one of the trust point of the "Signature
Validation Policy".
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B.5.2 Certification Path
There may be constraints on the use of certificates issued by one or
more CA(s) in the certificate chain and trust points. The two prime
constraints are certificate policy constraints and naming constraints:
* Certificate policy constraints limit the certification chain
between the user certificate and the certificate of the trusted
point to a given set of certificate policies, or equivalents
identified through certificate policy mapping.
* The naming constraints limit the forms of names that the CA is
allowed to certify.
Name constraints are particularly important when a "Signature policy"
identifies more than one trust point. In this case, a certificate of a
particular trusted point may only be used to verify signatures from
users with names permitted under the name constraint.
Certificate Authorities may be organized in a tree structure, this tree
structure may represent the trust relationship between various CA(s)
and the users CA. Alternatively, a mesh relationship may exist where a
combination of tree and peer cross-certificates may be used. The
requirement of the certificate path in this document is that it
provides the trust relationship between all the CAs and the signers
user certificate. The starting point from a verification point of view,
is the "trust point". A trust point is usually a CA that publishes
self-certified certificates, is the starting point from which the
verifier verifies the certificate chain. Naming constraints may
apply from the trust point, in which case they apply throughout the set
of certificates that make up the certificate path down to the signer's
user certificate.
Policy constraints can be easier to process but to be effective require
the presence of a certificate policy identifier in the certificates
used in a certification path.
Certificate path processing, thus generally starts with one of the
trust point from the signature policy and ends with the user
certificate. The certificate path processing procedures defined in RFC
2459 clause 6 identifies the following initial parameters that are
selected by the verifier in certificate path processing:
* acceptable certificate policies;
* naming constraints in terms of constrained and excluded naming
subtree;
* requirements for explicit certificate policy indication and
whether certificate policy mapping are allowed;
* restrictions on the certificate path length.
The signature validation policy identifies constraints on these
parameters.
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B.6 Revocation Rules
The signature policy should defines rules specifying requirements for
the use of certificate revocation lists (CRLs) and/or on-line
certificate status check service to check the validity of a certificate.
These rules specify the mandated minimum checks that must be carried
out.
It is expected that in many cases either check may be selected with
CRLs checks being carried out for certificate status that are
unavailable from OCSP servers. The verifier may take into account
information in the certificate in deciding how best to check the
revocation status (e.g. a certificate extension field about authority
information access or a CRL distribution point) provided that it does
not conflict with the signature policy revocation rules.
B.7 Rules for the Use of Roles
Roles can be supported as claimed roles or as certified roles using
Attribute Certificates.
B.7.1 Attribute Values
When signature under a role is mandated by the signature policy, then
either Attribute Certificates may be used or the signer may provide a
claimed role attribute. The acceptable attribute types or values may be
dependent on the type of commitment. For example, a user may have
several roles that allow the user to sign data that imply commitments
based on one or more of his roles.
B.7.2 Trust Points for Certified Attributes
When a signature under a certified role is mandated by the signature
policy, Attribute Authorities are used and need to be validated as part
of the overall validation of the electronic signature. The trust points
for Attribute Authorities do not need to be the same as the trust
points to evaluate a certificate from the CA of the signer. Thus the
trust point for verifying roles need not be the same as trust point
used to validate the certificate path of the user's key.
Naming and certification policy constraints may apply to the AA in
similar circumstance to when they apply to CA. Constraints on the AA
and CA need not be exactly the same.
AA(s) may be used when a signer is creating a signature on behalf of an
organization, they can be particularly useful when the signature
represents an organizational role. AA(s) may or may not be the same
authority as CA(s).
Thus, the Signature Policy identifies trust points that can be used for
Attribute Authorities, either by reference to the same trust points as
used for Certification Authorities, or by an independent list.
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B.7.3 Certification Path for Certified Attributes
Attribute Authorities may be organized in a tree structure in similar
way to CA where the AAs are the leafs of such a tree. Naming and other
constraints may be required on attribute certificate paths in a similar
manner to other electronic signature certificate paths.
Thus, the Signature Policy identify constraints on the following
parameters used as input to the certificate path processing:
* acceptable certificate policies, including requirements for
explicit certificate policy indication and whether certificate
policy mapping is allowed;
* naming constraints in terms of constrained and excluded naming
subtrees;
* restrictions on the certificate path length.
B.8 Rules for the Use of Timestamping and Timing
The following rules should be used when specifying, constraints on the
certificate paths for timestamping authorities, constraints on the
timestamping authority names and general timing constraints.
B.8.1 Trust Points and Certificate Paths
Signature keys from timestamping authorities will need to be supported
by a certification path. The certification path used for timestamping
authorities requires a trustpoint and possibly path constraints in the
same way that the certificate path for the signer's key.
B.8.2 Timestamping Authority Names
Restrictions may need to be placed by the validation policy on the
named entities that may act a timestamping authorities.
B.8.3 Timing Constraints - Caution Period
Before an electronic signature may really be valid, the verifier has to
be sure that the holder of the private key was really the only one in
possession of key at the time of signing. However, there is an
inevitable delay between a compromise or loss of key being noted, and a
report of revocation being distributed. To allow greater confidence in
the validity of a signature, a "cautionary period" may be identified
before a signature may be said to be valid with high confidence. A
verifier may revalidate a signature after this cautionary signature, or
wait for this period before validating a signature.
The validation policy may specify such a cautionary period.
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B.8.4 Timing Constraints - Timestamp Delay
There will be some delay between the time that a signature is created
and the time the signer's digital signature is timestamped. However,
the longer this elapsed period the greater the risk of the signature
being invalidated due to compromise or deliberate revocation of its
private signing key by the signer. Thus the signature policy should
specify a maximum acceptable delay between the signing time as claimed
by the signer and the time included within the timestamp.
B.9 Rules for Verification Data to be followed
By specifying the requirements on the signer and verifier the
responsibilities of the two parties can be clearly defined to establish
all the necessary information.
These verification data rules should include:
* requirements on the signer to provide given signed attributes;
* requirements on the verifier to obtain additional certificates, CRLs,
results of on line certificate status checks and to use timestamps (if
no already provided by the signer).
B.10 Rules for Algorithm Constraints and Key Lengths
The signature validation policy may identify a set of signing
algorithms (hashing, public key, combinations) and minimum key lengths
that may be used:
* by the signer in creating the signature;
* in end entity public key Certificates;
* CA Certificates;
* attribute Certificates;
* by the timestamping authority.
B.11 Other Signature Policy Rules
The signature policy may specify additional policy rules, for example
rules that relate to the environment used by the signer. These
additional rules may be defined in computer processable and/or human
readable form.
B.12 Signature Policy Protection
When signer or verifier obtains a copy of the Signature Policy from an
issuer, the source should be authenticated (for example by using
electronic signatures). When the signer references a signature policy
the Object Identifier (OID) of the policy, the hash value and the hash
algorithm OID of that policy must be included in the Electronic
Signature.
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It is a mandatory requirement of this present document that the
signature policy value computes to one, and only one hash value using
the specified hash algorithm. This means that there must be a single
binary value of the encoded form of the signature policy for the unique
hash value to be calculated. For example, there may exist a particular
file type, length and format on which the hash value is calculated
which is fixed and definitive for a particular signature policy.
The hash value may be obtained by:
the signer performing his own computation of the hash over the
signature policy using his preferred hash algorithm permitted by
the signature policy, and the definitive binary encoded form.
the signer, having verified the source of the policy, may use
both the hash algorithm and the hash value included in the
computer processable form of the policy (see section 6.1).
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