Internet Engineering Task Force (IETF) J. Solinas
Request for Comments: 5759 L. Zieglar
Category: Informational NSA
ISSN: 2070-1721 January 2010
Suite B Certificate and Certificate Revocation List (CRL) Profile
Abstract
This document specifies a base profile for X.509 v3 Certificates and
X.509 v2 Certificate Revocation Lists (CRLs) for use with the United
States National Security Agency's Suite B Cryptography. The reader
is assumed to have familiarity with RFC 5280, "Internet X.509 Public
Key Infrastructure Certificate and Certificate Revocation List (CRL)
Profile".
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc5759.
Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction ....................................................2
2. Conventions Used in This Document ...............................3
3. Requirements and Assumptions ....................................3
3.1. Implementing Suite B .......................................3
3.2. Suite B Object Identifiers .................................4
4. Suite B Certificate and Certificate Extensions Profile ..........4
4.1. signatureAlgorithm .........................................4
4.2. signatureValue .............................................5
4.3. Version ....................................................6
4.4. SubjectPublicKeyInfo .......................................6
4.5. Certificate Extensions for Particular Types of
Certificates ...............................................7
4.5.1. Suite B Self-Signed CA Certificates .................7
4.5.2. Suite B Non-Self-Signed CA Certificates .............8
4.5.3. Suite B End Entity Signature and Key
Establishment Certificates ..........................8
5. Suite B CRL and CRL Extensions Profile ..........................9
6. Security Considerations .........................................9
7. IANA Considerations .............................................9
8. References .....................................................10
8.1. Normative References ......................................10
8.2. Informative References ....................................10
1. Introduction
This document specifies a base profile for X.509 v3 Certificates and
X.509 v2 Certificate Revocation Lists (CRLs) for use by applications
that support the United States National Security Agency's Suite B
Cryptography.
The reader is assumed to have familiarity with [RFC5280]. This Suite
B Certificate and CRL Profile is a profile of RFC 5280. All MUST-
level requirements of RFC 5280 apply throughout this profile and are
generally not repeated here. In cases where a MUST-level requirement
is repeated for emphasis, the text notes the requirement is "in
adherence with [RFC5280]". This profile contains changes that
elevate some MAY-level options in RFC 5280 to SHOULD-level and MUST-
level in this profile; this profile also contains changes that
elevate some SHOULD-level options in RFC 5280 to MUST-level for this
profile. All options from RFC 5280 that are not listed in this
profile remain at the requirement level of RFC 5280.
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The reader is also assumed to have familiarity with [RFC5480], which
specifies the syntax and semantics for the Subject Public Key
Information field in certificates that support Elliptic Curve
Cryptography and [RFC5758], which specifies algorithm identifiers for
Elliptic Curve Digital Signature Algorithm (ECDSA).
2. Conventions Used in This Document
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].
3. Requirements and Assumptions
The goal of this document is to define a base set of certificate and
CRL formats to support interoperability among Suite B solutions.
Specific communities, such as the US National Security Systems, may
define community profiles that further restrict certificate and CRL
formats by mandating the presence of extensions that are optional in
this base profile, defining new optional or critical extension types,
or restricting the values and/or presence of fields within existing
extensions. However, communications between distinct communities
MUST use the formats specified in this document when interoperability
is desired. (Applications may add additional non-critical extensions
to these formats but they MUST NOT assume that a remote peer will be
able to process them.)
3.1. Implementing Suite B
Every Suite B certificate MUST use the X.509 v3 format, and contain
either:
* An ECDSA-capable signing key, using curve P-256 or P-384; or
* An ECDH-capable (Elliptic Curve Diffie-Hellman) key
establishment key, using curve P-256 or P-384.
Every Suite B certificate and CRL MUST be signed using ECDSA. The
signing Certification Authority's (CA's) key MUST be on the curve
P-256 or P-384 if the certificate contains a key on the curve P-256.
If the certificate contains a key on the curve P-384, the signing
CA's key MUST be on the curve P-384. Any certificate and CRL MUST be
hashed using SHA-256 or SHA-384, matched to the size of the signing
CA's key.
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3.2. Suite B Object Identifiers
The primary OID structure for Suite B is as follows per [X9.62],
[SEC2], [RFC5480], and [RFC5758].
ansi-X9-62 OBJECT IDENTIFIER ::= {
iso(1) member-body(2) us(840) 10045 }
certicom-arc OBJECT IDENTIFIER ::= {
iso(1) identified-organization(3) certicom(132) }
id-ecPublicKey OBJECT IDENTIFIER ::= {
ansi-X9-62 keyType(2) 1 }
secp256r1 OBJECT IDENTIFIER ::= {
ansi-X9-62 curves(3) prime(1) 7 }
secp384r1 OBJECT IDENTIFIER ::= {
certicom-arc curve(0) 34 }
id-ecSigType OBJECT IDENTIFIER ::= {
ansi-X9-62 signatures(4) }
ecdsa-with-SHA256 OBJECT IDENTIFIER ::= {
id-ecSigType ecdsa-with-SHA2(3) 2 }
ecdsa-with-SHA384 OBJECT IDENTIFIER ::= {
id-ecSigType ecdsa-with-SHA2(3) 3 }
4. Suite B Certificate and Certificate Extensions Profile
This Suite B certificate profile is a profile of [RFC5280]. The
changes in the requirements from RFC 5280 are listed here. Note that
RFC 5280 has varying mandates for marking extensions as critical or
non-critical. This profile changes some of those mandates for
extensions that are included in Suite B certificates.
4.1. signatureAlgorithm
The two algorithm identifiers used by Suite B are:
1.2.840.10045.4.3.2 for ecdsa-with-SHA256 and 1.2.840.10045.4.3.3 for
ecdsa-with-SHA384, as described in [RFC5758] AND [X9.62].
The parameters MUST be absent as per [RFC5758].
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4.2. signatureValue
ECDSA digital signature generation is described in [FIPS186-3]. An
ECDSA signature value is comprised of two unsigned integers, denoted
as r and s. r and s MUST be represented as ASN.1 INTEGERs. If the
high order bit of the unsigned integer is a 1, an octet with the
value 0x00 MUST be prepended to the binary representation before
encoding it as an ASN.1 INTEGER. Unsigned integers for the P-256 and
P-384 curves can be a maximum of 32 and 48 bytes, respectively.
Therefore, converting each r and s to an ASN.1 INTEGER will result in
a maximum of 33 bytes for the P-256 curve and 49 bytes for the P-384
curve.
The ECDSA signatureValue in an X.509 certificate is encoded as a BIT
STRING value of a DER-encoded SEQUENCE of the two INTEGERS. As per
[RFC5480], the structure, included for convenience, is as follows:
ECDSA-Sig-Value ::= SEQUENCE {
r INTEGER,
s INTEGER
}
For example, in a signature using P-256 and hex notation:
r= 52e3f7b7 27fba9e8 eddb1d08 3b75c188
2517e6dc 63ded9c0 524f8f9a 45dc8661
s= b8930438 de8d33bd ab12c3a2 bdad9795
92a1fd65 76d1734c 3eb0af34 0456aef4
r represented as a DER-encoded INTEGER:
022052e3 f7b727fb a9e8eddb 1d083b75
c1882517 e6dc63de d9c0524f 8f9a45dc
8661
s represented as a DER-encoded INTEGER:
022100b8 930438de 8d33bdab 12c3a2bd
ad979592 a1fd6576 d1734c3e b0af3404
56aef4
Representation of SEQUENCE of r and s:
30450220 52e3f7b7 27fba9e8 eddb1d08
3b75c188 2517e6dc 63ded9c0 524f8f9a
45dc8661 022100b8 930438de 8d33bdab
12c3a2bd ad979592 a1fd6576 d1734c3e
b0af3404 56aef4
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Representation of resulting signatureValue:
03480030 45022052 e3f7b727 fba9e8ed
db1d083b 75c18825 17e6dc63 ded9c052
4f8f9a45 dc866102 2100b893 0438de8d
33bdab12 c3a2bdad 979592a1 fd6576d1
734c3eb0 af340456 aef4
4.3. Version
For this profile, Version MUST be 3, which means the value MUST be
set to 2.
4.4. SubjectPublicKeyInfo
For ECDSA signing keys and ECDH key agreement keys, the algorithm ID,
id-ecPublicKey, MUST be used.
The parameters of the AlgorithmIdentifier in this field MUST use the
namedCurve option. The specifiedCurve and implicitCurve options
described in [RFC5480] MUST NOT be used. The namedCurve MUST be
either the OID for secp256r1 (curve P-256) or secp384r1 (curve P-384)
[RFC5480].
The elliptic curve public key, ECPoint, SHALL be the OCTET STRING
representation of an elliptic curve point following the conversion
routine in section 2.2 of [RFC5480] and sections 2.3.1 and 2.3.2 of
[SEC1].
Suite B implementations MAY use either the uncompressed form or the
compressed form of the elliptic curve point [RFC5480]. For
interoperability purposes, all relying parties MUST be prepared to
process the uncompressed form.
The elliptic curve public key (an ECPoint that is an OCTET STRING) is
mapped to a subjectPublicKey (a BIT STRING) as follows: the most
significant bit of the OCTET STRING becomes the most significant bit
of the BIT STRING and the least significant bit of the OCTET STRING
becomes the least significant bit of the BIT STRING [RFC5480].
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An octet string representation of a P-256 uncompressed elliptic curve
point:
046cc93a 2cdb0308 47fa0734 2bc8e130
4c77f04f 63557372 43f3a5d7 f51baa82
23d21ebf b87d9944 f7ec170d 64f9924e
9ce20e4d 361c2db5 f1d52257 4259edad
5e
A DER-encoded bit string representation of the subject public key:
03420004 6cc93a2c db030847 fa07342b
c8e1304c 77f04f63 55737243 f3a5d7f5
1baa8223 d21ebfb8 7d9944f7 ec170d64
f9924e9c e20e4d36 1c2db5f1 d5225742
59edad5e
A DER-encoded representation of the AlgorithmIdentifier:
30130607 2a8648ce 3d020106 082a8648
ce3d0301 07
A DER-encoded representation of the subjectPublicKeyInfo using the
P-256 curve:
30593013 06072a86 48ce3d02 0106082a
8648ce3d 03010703 4200046c c93a2cdb
030847fa 07342bc8 e1304c77 f04f6355
737243f3 a5d7f51b aa8223d2 1ebfb87d
9944f7ec 170d64f9 924e9ce2 0e4d361c
2db5f1d5 22574259 edad5e
4.5. Certificate Extensions for Particular Types of Certificates
Different types of certificates in this profile have different
required and recommended extensions. Those are listed in this
section. Those extensions from RFC 5280 not explicitly listed in
this profile remain at the requirement levels of RFC 5280.
4.5.1. Suite B Self-Signed CA Certificates
In adherence with [RFC5280], self-signed CA certificates in this
profile MUST contain the subjectKeyIdentifier, keyUsage, and
basicConstraints extensions.
The keyUsage extension MUST be marked as critical. The keyCertSign
and cRLSign bits MUST be set. The digitalSignature and
nonRepudiation bits MAY be set. All other bits MUST NOT be set.
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In adherence with [RFC5280], the basicConstraints extension MUST be
marked as critical. The cA boolean MUST be set to indicate that the
subject is a CA and the pathLenConstraint MUST NOT be present.
4.5.2. Suite B Non-Self-Signed CA Certificates
Non-self-signed CA Certificates in this profile MUST contain the
authorityKeyIdentifier, keyUsage, and basicConstraints extensions. If
there is a policy to be asserted, then the certificatePolicies
extension MUST be included.
The keyUsage extension MUST be marked as critical. The keyCertSign
and CRLSign bits MUST be set. The digitalSignature and
nonRepudiation bits MAY be set. All other bits MUST NOT be set.
In adherence with [RFC5280], the basicConstraints extension MUST be
marked as critical. The cA boolean MUST be set to indicate that the
subject is a CA and the pathLenConstraint subfield is OPTIONAL.
If a policy is asserted, the certificatePolicies extension MUST be
marked as non-critical, MUST contain the OIDs for the applicable
certificate policies and SHOULD NOT use the policyQualifiers option.
If a policy is not asserted, the certificatePolicies extension MUST
be omitted.
Relying party applications conforming to this profile MUST be
prepared to process the policyMappings, policyConstraints, and
inhibitAnyPolicy extensions, regardless of criticality, following the
guidance in [RFC5280] when they appear in non-self-signed CA
certificates.
4.5.3. Suite B End Entity Signature and Key Establishment Certificates
In adherence with [RFC5280], end entity certificates in this profile
MUST contain the authorityKeyIdentifier and keyUsage extensions. If
there is a policy to be asserted, then the certificatePolicies
extension MUST be included. End entity certificates SHOULD contain
the subjectKeyIdentifier extension.
The keyUsage extension MUST be marked as critical.
For end entity digital signature certificates, the keyUsage extension
MUST be set for digitalSignature. The nonRepudiation bit MAY be set.
All other bits in the keyUsage extension MUST NOT be set.
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For end entity key establishment certificates, the keyUsage extension
MUST BE set for keyAgreement. The encipherOnly or decipherOnly bit
MAY be set. All other bits in the keyUsage extension MUST NOT be
set.
If a policy is asserted, the certificatePolicies extension MUST be
marked as non-critical, MUST contain the OIDs for the applicable
certificate policies and SHOULD NOT use the policyQualifiers option.
If a policy is not asserted, the certificatePolicies extension MUST
be omitted.
5. Suite B CRL and CRL Extensions Profile
This Suite B CRL profile is a profile of [RFC5280]. There are
changes in the requirements from [RFC5280] for the signatures on CRLs
of this profile.
The signatures on CRLs in this profile MUST follow the same rules
from this profile that apply to signatures in the certificates, see
section 4.
6. Security Considerations
The security considerations in [RFC5280], [RFC5480], and [RFC5758]
apply.
A single key pair SHOULD NOT be used for both signature and key
establishment per [SP-800-57].
The Suite B algorithms provide significantly improved performance
when compared to equivalent-strength cryptography that does not
employ elliptic curve cryptography. Where performance has previously
been an impediment, use of Suite B may permit employment of PKI-based
cryptographic security mechanisms.
7. IANA Considerations
This document makes extensive use of object identifiers to register
public key types, elliptic curves, and algorithms. Most of them are
registered in the ANSI X9.62 arc with the exception of some of the
curves, which are in the Certicom, Inc. arc (these curves have been
adopted by ANSI and NIST). Extensions in certificates and CRLs are
identified using the object identifiers defined in an arc delegated
by IANA to the PKIX working group. No further action by IANA is
necessary for this document or any anticipated updates.
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8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation
List (CRL) Profile", RFC 5280, May 2008.
[RFC5480] Turner, S., Brown, D., Yiu, K., Housley, R., and T.
Polk, "Elliptic Curve Cryptography Subject Public Key
Information", RFC 5480, March 2009.
[RFC5758] Dang, Q., Santesson, S., Moriarty, K., Brown, D., and T.
Polk, "Internet X.509 Public Key Infrastructure:
Additional Algorithms and Identifiers for DSA and
ECDSA", RFC 5758, January 2010.
8.2. Informative References
[FIPS186-3] "Digital Signature Standard (DSS)", June 2009.
[SEC1] Standards for Efficient Cryptography, "SEC1: Elliptic
Curve Cryptography", September 2000.
[SEC2] Standards for Efficient Cryptography, "SEC 2:
Recommended Elliptic Curve Domain Parameters", September
2000.
[SP-800-57] Barker, E., Barker, W., Burr, W., Polk, W. Smid, M.,
"NIST SP-800-57:Recommendation for Key Management-Part
1: General", March 2007.
[X9.62] ANS X9.62, "Public Key Cryptography for the Financial
Services Industry; The Elliptic Curve Digital Signature
Algorithm (ECDSA)", December 2005.
[X9.63] ANS X9.63, "Public Key Cryptography for the Financial
Services Industry; Key Agreement and Key Transport Using
Elliptic Curve Cryptography", December 2001.
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Authors' Addresses
Jerome Solinas
National Information Assurance Research Laboratory
National Security Agency
EMail: jasolin@orion.ncsc.mil
Lydia Zieglar
National Information Assurance Research Laboratory
National Security Agency
EMail: llziegl@tycho.ncsc.mil
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RFC, FYI, BCP