Network Working Group J. Schaad
Request for Comments: 5035 Soaring Hawk Consulting
Updates: 2634 August 2007
Category: Standards Track
Enhanced Security Services (ESS) Update:
Adding CertID Algorithm Agility
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Abstract
In the original Enhanced Security Services for S/MIME document (RFC
2634), a structure for cryptographically linking the certificate to
be used in validation with the signature was introduced; this
structure was hardwired to use SHA-1. This document allows for the
structure to have algorithm agility and defines a new attribute for
this purpose.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Notation . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2. Updates to RFC 2634 . . . . . . . . . . . . . . . . . . . 2
2. Replace Section 5.4 'Signing Certificate Attribute
Definitions' . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Insert New Section 5.4.1 'Signing Certificate Attribute
Definition Version 2' . . . . . . . . . . . . . . . . . . . . 4
4. Insert New Section 5.4.1.1 'Certificate Identification
Version 2' . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Insert New Section 5.4.2 'Signing Certificate Attribute
Definition Version 1' . . . . . . . . . . . . . . . . . . . . 7
6. Insert New Section 5.4.2.1 'Certificate Identification
Version 1' . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. Normative References . . . . . . . . . . . . . . . . . . . . . 10
Appendix A. ASN.1 Module . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
In the original Enhanced Security Services (ESS) for S/MIME document
[ESS], a structure for cryptographically linking the certificate to
be used in validation with the signature was defined. This
structure, called ESSCertID, identifies a certificate by its hash.
The structure is hardwired to use a SHA-1 hash value. The recent
attacks on SHA-1 require that we define a new attribute that allows
for the use of different algorithms. This document performs that
task.
This document defines the structure ESSCertIDv2 along with a new
attribute SigningCertificateV2, which uses the updated structure.
This document allows for the structure to have algorithm agility by
including an algorithm identifier and defines a new signed attribute
to use the new structure.
This document specifies the continued use of ESSCertID to ensure
compatibility when SHA-1 is used for certificate disambiguation.
1.1. Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
1.2. Updates to RFC 2634
This document updates Section 5.4 of RFC 2634. Once the updates are
applied, the revised section will have the following structure:
5.4 Signing Certificate Attribute Definitions
5.4.1 Signing Certificate Attribute Definition Version 2
5.4.1.1 Certificate Identification Version 2
5.4.2 Signing Certificate Attribute Definition Version 1
5.4.2.1 Certificate Identification Version 1
In addition, the ASN.1 module in Appendix A is replaced.
2. Replace Section 5.4 'Signing Certificate Attribute Definitions'
5.4 Signing Certificate Attribute Definitions
The signing certificate attribute is designed to prevent simple
substitution and re-issue attacks, and to allow for a restricted set
of certificates to be used in verifying a signature.
Two different attributes exist for this due to a flaw in the original
design. The only substantial difference between the two attributes
is that SigningCertificateV2 allows for hash algorithm agility, while
SigningCertificate forces the use of the SHA-1 hash algorithm. With
the recent advances in the ability to create hash collisions for
SHA-1, it is wise to move forward sooner rather than later.
When the SHA-1 hash function is used, the SigningCertificate
attribute MUST be used. The SigningCertificateV2 attribute MUST be
used if any algorithm other than SHA-1 is used and SHOULD NOT be used
for SHA-1. Applications SHOULD recognize both attributes as long as
they consider SHA-1 able to distinguish between two different
certificates, (i.e., the possibility of a collision is sufficiently
low). If both attributes exist in a single message, they are
independently evaluated.
Four cases exist that need to be taken into account when using this
attribute for correct processing:
1. Signature validates and the hashes match: This is the success
case.
2. Signature validates and the hashes do not match: In this case,
the certificate contained the correct public key, but the
certificate containing the public key is not the one that the
signer intended to be used. In this case the application should
attempt a search for a different certificate with the same public
key and for which the hashes match. If no such certificate can
be found, this is a failure case.
3. Signature fails validation and the hashes match: In this case, it
can be assumed that the signature has been modified in some
fashion. This is a failure case.
4. Signature fails validation and the hashes do not match: In this
case, it can be either that the signature has been modified, or
that the wrong certificate has been used. Applications should
attempt a search for a different certificate that matches the
hash value in the attribute and use the new certificate to retry
the signature validation.
3. Insert New Section 5.4.1 'Signing Certificate Attribute Definition
Version 2'
5.4.1 Signing Certificate Attribute Definition Version 2
The signing certificate attribute is designed to prevent the simple
substitution and re-issue attacks, and to allow for a restricted set
of certificates to be used in verifying a signature.
SigningCertificateV2 is identified by the OID:
id-aa-signingCertificateV2 OBJECT IDENTIFIER ::= { iso(1)
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
smime(16) id-aa(2) 47 }
The attribute has the ASN.1 definition:
SigningCertificateV2 ::= SEQUENCE {
certs SEQUENCE OF ESSCertIDv2,
policies SEQUENCE OF PolicyInformation OPTIONAL
}
certs
contains the list of certificates that are to be used in
validating the message. The first certificate identified in the
sequence of certificate identifiers MUST be the certificate used
to verify the signature. The encoding of the ESSCertIDv2 for this
certificate SHOULD include the issuerSerial field. If other
constraints ensure that issuerAndSerialNumber will be present in
the SignerInfo, the issuerSerial field MAY be omitted. The
certificate identified is used during the signature verification
process. If the hash of the certificate does not match the
certificate used to verify the signature, the signature MUST be
considered invalid.
If more than one certificate is present, subsequent certificates
limit the set of certificates that are used during validation.
Certificates can be either attribute certificates (limiting
authorizations) or public key certificates (limiting path
validation). The issuerSerial field (in the ESSCertIDv2
structure) SHOULD be present for these certificates, unless the
client who is validating the signature is expected to have easy
access to all the certificates required for validation. If only
the signing certificate is present in the sequence, there are no
restrictions on the set of certificates used in validating the
signature.
policies
contains a sequence of policy information terms that identify
those certificate policies that the signer asserts apply to the
certificate, and under which the certificate should be relied
upon. This value suggests a policy value to be used in the
relying party's certification path validation. The definition of
PolicyInformation can be found in [RFC3280].
If present, the SigningCertificateV2 attribute MUST be a signed
attribute; it MUST NOT be an unsigned attribute. CMS defines
SignedAttributes as a SET OF Attribute. A SignerInfo MUST NOT
include multiple instances of the SigningCertificateV2 attribute.
CMS defines the ASN.1 syntax for the signed attributes to include
attrValues SET OF AttributeValue. A SigningCertificateV2 attribute
MUST include only a single instance of AttributeValue. There MUST
NOT be zero or multiple instances of AttributeValue present in the
attrValues SET OF AttributeValue.
4. Insert New Section 5.4.1.1 'Certificate Identification Version 2'
Insert the following text as a new section.
5.4.1.1 Certificate Identification Version 2
The best way to identify certificates is an often-discussed issue.
The ESSCertIDv2 structure supplies two different fields that are used
for this purpose.
The hash of the entire certificate allows for a verifier to check
that the certificate used in the verification process was the same
certificate the signer intended. Hashes are convenient in that they
are frequently used by certificate stores as a method of indexing and
retrieving certificates as well. The use of the hash is required by
this structure since the detection of substituted certificates is
based on the fact they would map to different hash values.
The issuer/serial number pair is the method of identification of
certificates used in [RFC3280]. That document imposes a restriction
for certificates that the issuer distinguished name must be present.
The issuer/serial number pair would therefore normally be sufficient
to identify the correct signing certificate. (This assumes the same
issuer name is not reused from the set of trust anchors.) The
issuer/serial number pair can be stored in the sid field of the
SignerInfo object. However, the sid field is not covered by the
signature. In the cases where the issuer/serial number pair is not
used in the sid or the issuer/serial number pair needs to be signed,
it SHOULD be placed in the issuerSerial field of the ESSCertIDv2
structure.
Attribute certificates and additional public key certificates
containing information do not have an issuer/serial number pair
represented anywhere in a SignerInfo object. When an attribute
certificate or an additional public key certificate is not included
in the SignedData object, it becomes much more difficult to get the
correct set of certificates based only on a hash of the certificate.
For this reason, these certificates SHOULD be identified by the
IssuerSerial object.
This document defines a certificate identifier as:
ESSCertIDv2 ::= SEQUENCE {
hashAlgorithm AlgorithmIdentifier
DEFAULT {algorithm id-sha256},
certHash Hash,
issuerSerial IssuerSerial OPTIONAL
}
Hash ::= OCTET STRING
IssuerSerial ::= SEQUENCE {
issuer GeneralNames,
serialNumber CertificateSerialNumber
}
The fields of ESSCertIDv2 are defined as follows:
hashAlgorithm
contains the identifier of the algorithm used in computing
certHash.
certHash
is computed over the entire DER-encoded certificate (including the
signature) using the SHA-1 algorithm.
issuerSerial
holds the identification of the certificate. The issuerSerial
would normally be present unless the value can be inferred from
other information (e.g., the sid field of the SignerInfo object).
The fields of IssuerSerial are defined as follows:
issuer
contains the issuer name of the certificate. For non-attribute
certificates, the issuer MUST contain only the issuer name from
the certificate encoded in the directoryName choice of
GeneralNames. For attribute certificates, the issuer MUST contain
the issuer name field from the attribute certificate.
serialNumber
holds the serial number that uniquely identifies the certificate
for the issuer.
5. Insert New Section 5.4.2 'Signing Certificate Attribute Definition
Version 1'
(Note: This section does not present new material. This section
contains the original contents of Section 5.4 in [ESS], which are
retained with minor changes in this specification to achieve
backwards compatibility.)
Insert the following text as a new section.
5.4.2 Signing Certificate Attribute Definition Version 1
The signing certificate attribute is designed to prevent the simple
substitution and re-issue attacks, and to allow for a restricted set
of certificates to be used in verifying a signature.
The definition of SigningCertificate is
SigningCertificate ::= SEQUENCE {
certs SEQUENCE OF ESSCertID,
policies SEQUENCE OF PolicyInformation OPTIONAL
}
id-aa-signingCertificate OBJECT IDENTIFIER ::= { iso(1)
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
smime(16) id-aa(2) 12 }
The first certificate identified in the sequence of certificate
identifiers MUST be the certificate used to verify the signature.
The encoding of the ESSCertID for this certificate SHOULD include the
issuerSerial field. If other constraints ensure that
issuerAndSerialNumber will be present in the SignerInfo, the
issuerSerial field MAY be omitted. The certificate identified is
used during the signature verification process. If the hash of the
certificate does not match the certificate used to verify the
signature, the signature MUST be considered invalid.
If more than one certificate is present in the sequence of
ESSCertIDs, the certificates after the first one limit the set of
certificates that are used during validation. Certificates can be
either attribute certificates (limiting authorizations) or public key
certificates (limiting path validation). The issuerSerial field (in
the ESSCertID structure) SHOULD be present for these certificates,
unless the client who is validating the signature is expected to have
easy access to all the certificates required for validation. If only
the signing certificate is present in the sequence, there are no
restrictions on the set of certificates used in validating the
signature.
The sequence of policy information terms identifies those certificate
policies that the signer asserts apply to the certificate, and under
which the certificate should be relied upon. This value suggests a
policy value to be used in the relying party's certification path
validation.
If present, the SigningCertificate attribute MUST be a signed
attribute; it MUST NOT be an unsigned attribute. Cryptographic
Message Syntax (CMS) defines SignedAttributes as a SET OF Attribute.
A SignerInfo MUST NOT include multiple instances of the
SigningCertificate attribute. CMS defines the ASN.1 syntax for the
signed attributes to include attrValues SET OF AttributeValue. A
SigningCertificate attribute MUST include only a single instance of
AttributeValue. There MUST NOT be zero or multiple instances of
AttributeValue present in the attrValues SET OF AttributeValue.
6. Insert New Section 5.4.2.1 'Certificate Identification Version 1'
(Note: This section does not present new material. This section
contains the original contents of Section 5.4 in [ESS], which are
retained with minor changes in this specification to achieve
backwards compatibility.)
Delete old Section 5.4.1
Insert the following as new text
5.4.2.1 Certificate Identification Version 1
Certificates are uniquely identified using the information in the
ESSCertID structure. Discussion can be found in Section 5.4.1.1.
This document defines a certificate identifier as:
ESSCertID ::= SEQUENCE {
certHash Hash,
issuerSerial IssuerSerial OPTIONAL
}
The fields of ESSCertID are defined as follows:
certHash
is computed over the entire DER-encoded certificate (including the
signature).
issuerSerial
holds the identification of the certificate. This field would
normally be present unless the value can be inferred from other
information (e.g., the sid field of the SignerInfo object).
The fields of IssuerSerial are discussed in Section 5.4.1.1
7. Security Considerations
This document is designed to address the security issue of a
substituted certificate used by the validator. If a different
certificate is used by the validator than the signer, the validator
may not get the correct result. An example of this would be that the
original certificate was revoked and a new certificate with the same
public key was issued for a different individual. Since the issuer/
serial number field is not protected, the attacker could replace this
and point to the new certificate and validation would be successful.
The attributes defined in this document are to be placed in locations
that are protected by the signature. This attribute does not provide
any additional security if placed in an unsigned or un-authenticated
location.
The attributes defined in this document permit a signer to select a
hash algorithm to identify a certificate. A poorly selected hash
algorithm may provide inadequate protection against certificate
substitution or result in denial of service for this protection. By
employing the attributes defined in this specification with the same
hash algorithm used for message signing, the sender can ensure that
these attributes provide commensurate security.
Since recipients must support the hash algorithm to verify the
signature, selecting the same hash algorithm also increases the
likelihood that the hash algorithm is supported in the context of
certificate identification. Note that an unsupported hash algorithm
for certificate identification does not preclude validating the
message but does deny the message recipient protection against
certificate substitution.
To ensure that legacy implementations are provided protection against
certificate substitution, clients are permitted to include both
ESScertID and ESScertIDv2 in the same message. Since these
attributes are generated and evaluated independently, the contents
could conceivably be in conflict. Specifically, where a signer has
multiple certificates containing the same public key, the two
attributes could specify different signing certificates. The result
of signature processing may vary depending on which certificate is
used to validate the signature.
Recipients that attempt to evaluate both attributes may choose to
reject such a message.
8. Normative References
[ESS] Hoffman, P., "Enhanced Security Services for S/MIME",
RFC 2634, June 1999.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, BCP 14, March 1997.
[RFC3280] Housley, R., Ford, W., Polk, W., and D. Solo, "Internet
X.509 Public Key Infrastructure Certificate and
Certificate Revocation List (CRL) Profile", RFC 3280,
April 2002.
[RFC3852] Housley, R., "Cryptographic Message Syntax (CMS)",
RFC 3852, July 2004.
[UTF8] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003.
Appendix A. ASN.1 Module
Replace the ASN.1 module in RFC 2634 with this one.
ExtendedSecurityServices-2006
{ iso(1) member-body(2) us(840) rsadsi(113549)
pkcs(1) pkcs-9(9) smime(16) modules(0) id-mod-ess-2006(30) }
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
IMPORTS
-- Cryptographic Message Syntax (CMS) [RFC3852]
ContentType, IssuerAndSerialNumber, SubjectKeyIdentifier
FROM CryptographicMessageSyntax2004 { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16)
modules(0) cms-2004(24)}
-- PKIX Certificate and CRL Profile, Section A.1 Explicity Tagged Module
-- 1988 Syntax [RFC3280]
AlgorithmIdentifier, CertificateSerialNumber
FROM PKIX1Explicit88 { iso(1) identified-organization(3) dod(6)
internet(1) security(5) mechanisms(5) pkix(7) id-mod(0)
id-pkix1-explicit(18) }
-- PKIX Certificate and CRL Profile, Sec A.2 Implicitly Tagged Module,
-- 1988 Syntax [RFC3280]
PolicyInformation, GeneralNames
FROM PKIX1Implicit88 {iso(1) identified-organization(3) dod(6)
internet(1) security(5) mechanisms(5) pkix(7) id-mod(0)
id-pkix1-implicit(19)};
-- Extended Security Services
-- The construct "SEQUENCE SIZE (1..MAX) OF" appears in several ASN.1
-- constructs in this module. A valid ASN.1 SEQUENCE can have zero or
-- more entries. The SIZE (1..MAX) construct constrains the SEQUENCE to
-- have at least one entry. MAX indicates the upper bound is
-- unspecified. Implementations are free to choose an upper bound that
-- suits their environment.
-- UTF8String ::= [UNIVERSAL 12] IMPLICIT OCTET STRING
-- The contents are formatted as described in [UTF8]
-- Section 2.7
ReceiptRequest ::= SEQUENCE {
signedContentIdentifier ContentIdentifier,
receiptsFrom ReceiptsFrom,
receiptsTo SEQUENCE SIZE (1..ub-receiptsTo) OF GeneralNames
}
ub-receiptsTo INTEGER ::= 16
id-aa-receiptRequest OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 1}
ContentIdentifier ::= OCTET STRING
id-aa-contentIdentifier OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 7}
ReceiptsFrom ::= CHOICE {
allOrFirstTier [0] AllOrFirstTier, -- formerly "allOrNone [0]AllOrNone"
receiptList [1] SEQUENCE OF GeneralNames
}
AllOrFirstTier ::= INTEGER { -- Formerly AllOrNone
allReceipts (0),
firstTierRecipients (1)
}
-- Section 2.8
Receipt ::= SEQUENCE {
version ESSVersion,
contentType ContentType,
signedContentIdentifier ContentIdentifier,
originatorSignatureValue OCTET STRING
}
id-ct-receipt OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-ct(1) 1}
ESSVersion ::= INTEGER { v1(1) }
-- Section 2.9
ContentHints ::= SEQUENCE {
contentDescription UTF8String (SIZE (1..MAX)) OPTIONAL,
contentType ContentType
}
id-aa-contentHint OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 4}
-- Section 2.10
MsgSigDigest ::= OCTET STRING
id-aa-msgSigDigest OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 5}
-- Section 2.11
ContentReference ::= SEQUENCE {
contentType ContentType,
signedContentIdentifier ContentIdentifier,
originatorSignatureValue OCTET STRING
}
id-aa-contentReference OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 10 }
-- Section 3.2
ESSSecurityLabel ::= SET {
security-policy-identifier SecurityPolicyIdentifier,
security-classification SecurityClassification OPTIONAL,
privacy-mark ESSPrivacyMark OPTIONAL,
security-categories SecurityCategories OPTIONAL
}
id-aa-securityLabel OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 2}
SecurityPolicyIdentifier ::= OBJECT IDENTIFIER
SecurityClassification ::= INTEGER {
unmarked (0),
unclassified (1),
restricted (2),
confidential (3),
secret (4),
top-secret (5)
}(0..ub-integer-options)
ub-integer-options INTEGER ::= 256
ESSPrivacyMark ::= CHOICE {
pString PrintableString (SIZE (1..ub-privacy-mark-length)),
utf8String UTF8String (SIZE (1..MAX))
}
ub-privacy-mark-length INTEGER ::= 128
SecurityCategories ::= SET SIZE (1..ub-security-categories) OF
SecurityCategory
ub-security-categories INTEGER ::= 64
SecurityCategory ::= SEQUENCE {
type [0] OBJECT IDENTIFIER,
value [1] ANY DEFINED BY type
}
--Note: The aforementioned SecurityCategory syntax produces identical
--hex encodings as the following SecurityCategory syntax that is
--documented in the X.411 specification:
--
--SecurityCategory ::= SEQUENCE {
-- type [0] SECURITY-CATEGORY,
-- value [1] ANY DEFINED BY type }
--
--SECURITY-CATEGORY MACRO ::=
--BEGIN
--TYPE NOTATION ::= type | empty
--VALUE NOTATION ::= value (VALUE OBJECT IDENTIFIER)
--END
-- Section 3.4
EquivalentLabels ::= SEQUENCE OF ESSSecurityLabel
id-aa-equivalentLabels OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 9}
-- Section 4.4
MLExpansionHistory ::= SEQUENCE
SIZE (1..ub-ml-expansion-history) OF MLData
id-aa-mlExpandHistory OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 3 }
ub-ml-expansion-history INTEGER ::= 64 MLData ::= SEQUENCE {
mailListIdentifier EntityIdentifier,
expansionTime GeneralizedTime,
mlReceiptPolicy MLReceiptPolicy OPTIONAL
}
EntityIdentifier ::= CHOICE {
issuerAndSerialNumber IssuerAndSerialNumber,
subjectKeyIdentifier SubjectKeyIdentifier
}
MLReceiptPolicy ::= CHOICE {
none [0] NULL,
insteadOf [1] SEQUENCE SIZE (1..MAX) OF GeneralNames,
inAdditionTo [2] SEQUENCE SIZE (1..MAX) OF GeneralNames
}
-- Section 5.4
SigningCertificate ::= SEQUENCE {
certs SEQUENCE OF ESSCertID,
policies SEQUENCE OF PolicyInformation OPTIONAL
}
id-aa-signingCertificate OBJECT IDENTIFIER ::= { iso(1)
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
smime(16) id-aa(2) 12 }
SigningCertificateV2 ::= SEQUENCE {
certs SEQUENCE OF ESSCertIDv2,
policies SEQUENCE OF PolicyInformation OPTIONAL
}
id-aa-signingCertificateV2 OBJECT IDENTIFIER ::= { iso(1)
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
smime(16) id-aa(2) 47 }
id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2)
country(16) us(840) organization(1) gov(101)
csor(3) nistalgorithm(4) hashalgs(2) 1 }
ESSCertIDv2 ::= SEQUENCE {
hashAlgorithm AlgorithmIdentifier
DEFAULT {algorithm id-sha256},
certHash Hash,
issuerSerial IssuerSerial OPTIONAL
}
ESSCertID ::= SEQUENCE {
certHash Hash,
issuerSerial IssuerSerial OPTIONAL
}
Hash ::= OCTET STRING IssuerSerial ::= SEQUENCE {
issuer GeneralNames,
serialNumber CertificateSerialNumber
}
END
-- of ExtendedSecurityServices-2006
Author's Address
Jim Schaad
Soaring Hawk Consulting
PO Box 675
Gold Bar, WA 98251
EMail: jimsch@exmsft.com
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