Network Working Group M. Nystrom
Request for Comments: 2986 B. Kaliski
Obsoletes: 2314 RSA Security
Category: Informational November 2000
PKCS #10: Certification Request Syntax Specification
Version 1.7
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved.
Abstract
This memo represents a republication of PKCS #10 v1.7 from RSA
Laboratories' Public-Key Cryptography Standards (PKCS) series, and
change control is retained within the PKCS process. The body of this
document, except for the security considerations section, is taken
directly from the PKCS #9 v2.0 or the PKCS #10 v1.7 document.
This memo describes a syntax for certification requests.
Table of Contents
1. Introduction ................................................. 2
2. Definitions and notation ..................................... 2
2.1 Definitions ................................................. 2
2.2 Notation .................................................... 4
3. Overview ..................................................... 4
4. Certification request syntax ................................. 5
4.1 CertificationRequestInfo .................................... 5
4.2 CertificationRequest ........................................ 7
5. Security Considerations ...................................... 8
6. Authors' Addresses ........................................... 8
A. ASN.1 module ................................................. 9
B. Intellectual property considerations ........................ 10
C. Revision history ............................................ 10
D. References .................................................. 11
E. Contact information & About PKCS ............................ 12
Full Copyright Statement ........................................ 14
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RFC 2986 Certification Request Syntax Specification November 2000 1. Introduction This document describes syntax for certification requests. A certification request consists of a distinguished name, a public key, and optionally a set of attributes, collectively signed by the entity requesting certification. Certification requests are sent to a certification authority, which transforms the request into an X.509 [9] public-key certificate. (In what form the certification authority returns the newly signed certificate is outside the scope of this document. A PKCS #7 [2] message is one possibility.) The intention of including a set of attributes is twofold: to provide other information about a given entity , or a "challenge password" by which the entity may later request certificate revocation; and to provide attributes for inclusion in X.509 certificates. A non- exhaustive list of attributes is given in PKCS #9 [3]. Certification authorities may also require non-electronic forms of request and may return non-electronic replies. It is expected that descriptions of such forms, which are outside the scope of this document, will be available from certification authorities. The preliminary intended application of this document is to support PKCS #7 cryptographic messages, but it is expected that other applications will be developed (see e.g. [4]). 2. Definitions and notation 2.1 Definitions For the purposes of this document, the following definitions apply. ALGORITHM An information object class defined in X.509 to describe objects composed of an algorithm (a unique object identifier) and its parameters (any ASN.1 type). The values of objects in this class can be represented by the ASN.1 type AlgorithmIdentifier{}. ALGORITHM is defined as the "useful" information object class TYPE-IDENTIFIER, specified in [11], Annex A. AlgorithmIdentifier{} A useful parameterized version of X.509 type AlgorithmIdentifier is defined in this document. This type tightly binds pairs of algorithm object identifiers to their associated parameter types. When referenced, the single parameter of AlgorithmIdentifier{} specifies a constraint on the Nystrom & Kaliski Informational [Page 2]
RFC 2986 Certification Request Syntax Specification November 2000 pairs of values that may appear in that instance of the type. The encoded values of AlgorithmIdentifier{} are equivalent to those of type AlgorithmIdentifier. ASN.1 Abstract Syntax Notation One, as defined in the ASN.1 standards ([10], [11], [12], and [13]). ATTRIBUTE This class describes objects composed of an attribute (a unique object identifier) and an associated set of attribute values (any ASN.1 type). The values of objects in this class can be represented by type Attribute{}. Attribute{} A useful parameterized version of X.501 [8] type Attribute is defined in this document. This type tightly binds pairs of attribute type object identifiers to one or more attribute values types. In the ASN.1 open type notation, an attribute type is defined as ATTRIBUTE.&id and an attribute value as ATTRIBUTE.&Type. When referenced, the single parameter of Attribute{} specifies a constraint on the pairs of values that may appear in an instance of the type. The encoded values of Attribute{} are equivalent to those of type Attribute. BER Basic Encoding Rules for ASN.1, as defined in X.690 ([14]). Certificate A type that binds a subject entity's distinguished name to a public key with a digital signature. This type is defined in X.509. This type also contains the distinguished name of the certificate issuer (the signer), an issuer-specific serial number, the issuer's signature algorithm identifier, a validity period, and an optional set of certificate extensions. DER Distinguished Encoding Rules for ASN.1, as defined in X.690. DER is a subset of BER. Name A type that uniquely identifies or "distinguishes" objects in an X.500 [7] directory. This type is defined in X.501. In an X.509 certificate, the type identifies the certificate issuer and the certificate subject, the entity whose public key is certified. Nystrom & Kaliski Informational [Page 3]
RFC 2986 Certification Request Syntax Specification November 2000 2.2 Notation No special notation is used in this document. 3. Overview A certification request consists of three parts: "certification request information," a signature algorithm identifier, and a digital signature on the certification request information. The certification request information consists of the entity's distinguished name, the entity's public key, and a set of attributes providing other information about the entity. The process by which a certification request is constructed involves the following steps: 1. A CertificationRequestInfo value containing a subject distinguished name, a subject public key, and optionally a set of attributes is constructed by an entity requesting certification. 2. The CertificationRequestInfo value is signed with the subject entity's private key. (See Section 4.2.) 3. The CertificationRequestInfo value, a signature algorithm identifier, and the entity's signature are collected together into a CertificationRequest value, defined below. A certification authority fulfills the request by authenticating the requesting entity and verifying the entity's signature, and, if the request is valid, constructing an X.509 certificate from the distinguished name and public key, the issuer name, and the certification authority's choice of serial number, validity period, and signature algorithm. If the certification request contains any PKCS #9 attributes, the certification authority may also use the values in these attributes as well as other information known to the certification authority to construct X.509 certificate extensions. In what form the certification authority returns the new certificate is outside the scope of this document. One possibility is a PKCS #7 cryptographic message with content type signedData, following the degenerate case where there are no signers. The return message may include a certification path from the new certificate to the certification authority. It may also include other certificates such as cross-certificates that the certification authority considers helpful, and it may include certificate-revocation lists (CRLs). Another possibility is that the certification authority inserts the new certificate into a central database. Nystrom & Kaliski Informational [Page 4]
RFC 2986 Certification Request Syntax Specification November 2000 Note 1 - An entity would typically send a certification request after generating a public-key/private-key pair, but may also do so after a change in the entity's distinguished name. Note 2 - The signature on the certification request prevents an entity from requesting a certificate with another party's public key. Such an attack would give the entity the minor ability to pretend to be the originator of any message signed by the other party. This attack is significant only if the entity does not know the message being signed and the signed part of the message does not identify the signer. The entity would still not be able to decrypt messages intended for the other party, of course. Note 3 - How the entity sends the certification request to a certification authority is outside the scope of this document. Both paper and electronic forms are possible. Note 4 - This document is not compatible with the certification request syntax for Privacy-Enhanced Mail, as described in RFC 1424 [5]. The syntax here differs in three respects: It allows a set of attributes; it does not include issuer name, serial number, or validity period; and it does not require an "innocuous" message to be signed. This document is designed to minimize request size, an important feature for certification authorities accepting requests on paper. 4. Certification request syntax This section is divided into two parts. The first part describes the certification-request-information type CertificationRequestInfo, and the second part describes the top-level type CertificationRequest. 4.1 CertificationRequestInfo Certification request information shall have ASN.1 type CertificationRequestInfo: CertificationRequestInfo ::= SEQUENCE { version INTEGER { v1(0) } (v1,...), subject Name, subjectPKInfo SubjectPublicKeyInfo{{ PKInfoAlgorithms }}, attributes [0] Attributes{{ CRIAttributes }} } SubjectPublicKeyInfo { ALGORITHM : IOSet} ::= SEQUENCE { algorithm AlgorithmIdentifier {{IOSet}}, subjectPublicKey BIT STRING } Nystrom & Kaliski Informational [Page 5]
RFC 2986 Certification Request Syntax Specification November 2000 PKInfoAlgorithms ALGORITHM ::= { ... -- add any locally defined algorithms here -- } Attributes { ATTRIBUTE:IOSet } ::= SET OF Attribute{{ IOSet }} CRIAttributes ATTRIBUTE ::= { ... -- add any locally defined attributes here -- } Attribute { ATTRIBUTE:IOSet } ::= SEQUENCE { type ATTRIBUTE.&id({IOSet}), values SET SIZE(1..MAX) OF ATTRIBUTE.&Type({IOSet}{@type}) } The components of type CertificationRequestInfo have the following meanings: version is the version number, for compatibility with future revisions of this document. It shall be 0 for this version of the standard. subject is the distinguished name of the certificate subject (the entity whose public key is to be certified). subjectPublicKeyInfo contains information about the public key being certified. The information identifies the entity's public-key algorithm (and any associated parameters); examples of public-key algorithms include the rsaEncryption object identifier from PKCS #1 [1]. The information also includes a bit-string representation of the entity's public key. For the public-key algorithm just mentioned, the bit string contains the DER encoding of a value of PKCS #1 type RSAPublicKey. The values of type SubjectPublicKeyInfo{} allowed for subjectPKInfo are constrained to the values specified by the information object set PKInfoAlgorithms, which includes the extension marker (...). Definitions of specific algorithm objects are left to specifications that reference this document. Such specifications will be interoperable with their future versions if any additional algorithm objects are added after the extension marker. attributes is a collection of attributes providing additional information about the subject of the certificate. Some attribute types that might be useful here are defined in PKCS #9. An example is the challenge-password attribute, which specifies a password by which the entity may request certificate revocation. Another example is information to appear in X.509 certificate extensions (e.g. the extensionRequest attribute from PKCS #9). The values of type Nystrom & Kaliski Informational [Page 6]
RFC 2986 Certification Request Syntax Specification November 2000 Attributes{} allowed for attributes are constrained to the values specified by the information object set CRIAttributes. Definitions of specific attribute objects are left to specifications that reference this document. Such specifications will be interoperable with their future versions if any additional attribute objects are added after the extension marker. 4.2 CertificationRequest A certification request shall have ASN.1 type CertificationRequest: CertificationRequest ::= SEQUENCE { certificationRequestInfo CertificationRequestInfo, signatureAlgorithm AlgorithmIdentifier{{ SignatureAlgorithms }}, signature BIT STRING } AlgorithmIdentifier {ALGORITHM:IOSet } ::= SEQUENCE { algorithm ALGORITHM.&id({IOSet}), parameters ALGORITHM.&Type({IOSet}{@algorithm}) OPTIONAL } SignatureAlgorithms ALGORITHM ::= { ... -- add any locally defined algorithms here -- } The components of type CertificationRequest have the following meanings: certificateRequestInfo is the "certification request information." It is the value being signed. signatureAlgorithm identifies the signature algorithm (and any associated parameters) under which the certification-request information is signed. For example, a specification might include an ALGORITHM object for PKCS #1's md5WithRSAEncryption in the information object set SignatureAlgorithms: SignatureAlgorithms ALGORITHM ::= { ..., { NULL IDENTIFIED BY md5WithRSAEncryption } } signature is the result of signing the certification request information with the certification request subject's private key. Nystrom & Kaliski Informational [Page 7]
RFC 2986 Certification Request Syntax Specification November 2000 The signature process consists of two steps: 1. The value of the certificationRequestInfo component is DER encoded, yielding an octet string. 2. The result of step 1 is signed with the certification request subject's private key under the specified signature algorithm, yielding a bit string, the signature. Note - An equivalent syntax for CertificationRequest could be written: CertificationRequest ::= SIGNED { EncodedCertificationRequestInfo } (CONSTRAINED BY { -- Verify or sign encoded -- CertificationRequestInfo -- }) EncodedCertificationRequestInfo ::= TYPE-IDENTIFIER.&Type(CertificationRequestInfo) SIGNED { ToBeSigned } ::= SEQUENCE { toBeSigned ToBeSigned, algorithm AlgorithmIdentifier { {SignatureAlgorithms} }, signature BIT STRING } 5. Security Considerations Security issues are discussed throughout this memo. 6. Authors' Addresses Magnus Nystrom RSA Security Box 10704 S-121 29 Stockholm Sweden EMail: magnus@rsasecurity.com Burt Kaliski RSA Security 20 Crosby Drive Bedford, MA 01730 USA EMail: bkaliski@rsasecurity.com Nystrom & Kaliski Informational [Page 8]
RFC 2986 Certification Request Syntax Specification November 2000 APPENDICES A. ASN.1 Module This appendix includes all of the ASN.1 type and value definitions contained in this document in the form of the ASN.1 module PKCS-10. PKCS-10 {iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-10(10) modules(1) pkcs-10(1)} DEFINITIONS IMPLICIT TAGS ::= BEGIN -- EXPORTS All -- -- All types and values defined in this module are exported for use -- in other ASN.1 modules. IMPORTS informationFramework, authenticationFramework FROM UsefulDefinitions {joint-iso-itu-t(2) ds(5) module(1) usefulDefinitions(0) 3} ATTRIBUTE, Name FROM InformationFramework informationFramework ALGORITHM FROM AuthenticationFramework authenticationFramework; -- Certificate requests CertificationRequestInfo ::= SEQUENCE { version INTEGER { v1(0) } (v1,...), subject Name, subjectPKInfo SubjectPublicKeyInfo{{ PKInfoAlgorithms }}, attributes [0] Attributes{{ CRIAttributes }} } SubjectPublicKeyInfo {ALGORITHM: IOSet} ::= SEQUENCE { algorithm AlgorithmIdentifier {{IOSet}}, subjectPublicKey BIT STRING } PKInfoAlgorithms ALGORITHM ::= { ... -- add any locally defined algorithms here -- } Attributes { ATTRIBUTE:IOSet } ::= SET OF Attribute{{ IOSet }} Nystrom & Kaliski Informational [Page 9]
RFC 2986 Certification Request Syntax Specification November 2000 CRIAttributes ATTRIBUTE ::= { ... -- add any locally defined attributes here -- } Attribute { ATTRIBUTE:IOSet } ::= SEQUENCE { type ATTRIBUTE.&id({IOSet}), values SET SIZE(1..MAX) OF ATTRIBUTE.&Type({IOSet}{@type}) } CertificationRequest ::= SEQUENCE { certificationRequestInfo CertificationRequestInfo, signatureAlgorithm AlgorithmIdentifier{{ SignatureAlgorithms }}, signature BIT STRING } AlgorithmIdentifier {ALGORITHM:IOSet } ::= SEQUENCE { algorithm ALGORITHM.&id({IOSet}), parameters ALGORITHM.&Type({IOSet}{@algorithm}) OPTIONAL } SignatureAlgorithms ALGORITHM ::= { ... -- add any locally defined algorithms here -- } END B. Intellectual property considerations RSA Security makes no patent claims on the general constructions described in this document, although specific underlying techniques may be covered. License to copy this document is granted provided that it is identified as "RSA Security Inc. Public-Key Cryptography Standards (PKCS)" in all material mentioning or referencing this document. RSA Security makes no representations regarding intellectual property claims by other parties. Such determination is the responsibility of the user. C. Revision history Version 1.0 Version 1.0 was the previous version of this document (also published as "version 1.5" in [6]). Nystrom & Kaliski Informational [Page 10]
RFC 2986 Certification Request Syntax Specification November 2000 Version 1.7 This version incorporates several editorial changes, including updates to the references, and changes to ASN.1 type definitions. The following substantive changes have been made: - This version refers to X.680-X.690, the current international standards for ASN.1 and its encoding rules. All references to X.208 and X.209 have been eliminated. - The X.690 standard requires that the encoded values of SET OF components be sorted in ascending order under DER. Regardless of this, applications should not rely on the ordering of attribute components. - All references to PKCS #6 Extended-Certificate Syntax Standard have been removed. With the addition of extensions to X.509 version 3 certificates, RSA Laboratories is withdrawing support for PKCS #6. Note - The reason for using version 1.7 for this document is to avoid confusion with [6], which is named version 1.5, and an unsupported PKCS #10 version named Version 1.6. D. References [1] RSA Laboratories. PKCS #1: RSA Encryption Standard. Version 2.0, October 1998. [2] RSA Laboratories. PKCS #7: Cryptographic Message Syntax Standard. Version 1.5, November 1993. [3] RSA Laboratories. PKCS #9: Selected Attribute Types. Version 2.0, February 2000. [4] Adams, C. and S. Farrell, "Internet X.509 Public Key Infrastructure - Certificate Management Protocols", RFC 2510, March 1999. [5] Kaliski, B., "Privacy Enhancement for Internet Electronic Mail: Part IV: Key Certification and Related Services", RFC 1424, February 1993. [6] Kaliski, B., "PKCS #10: Certification Request Syntax Version 1.5", RFC 2314, March 1998. Nystrom & Kaliski Informational [Page 11]
RFC 2986 Certification Request Syntax Specification November 2000 [7] ITU-T Recommendation X.500 (1997) | ISO/IEC 9594-1:1998, Information technology - Open Systems Interconnection - The Directory: Overview of concepts, models and services. [8] ITU-T Recommendation X.501 (1993) | ISO/IEC 9594-2:1995, Information technology - Open Systems Interconnection - The Directory: Models. [9] ITU-T Recommendation X.509 (1997) | ISO/IEC 9594-8:1998, Information technology - Open Systems Interconnection -The Directory: Authentication framework. [10] ITU-T Recommendation X.680 (1997) | ISO/IEC 8824-1:1998, Information Technology - Abstract Syntax Notation One (ASN.1): Specification of Basic Notation. [11] ITU-T Recommendation X.681 (1997) | ISO/IEC 8824-2:1998, Information Technology - Abstract Syntax Notation One (ASN.1): Information Object Specification. [12] ITU-T Recommendation X.682 (1997) | ISO/IEC 8824-3:1998, Information Technology - Abstract Syntax Notation One (ASN.1): Constraint Specification. [13] ITU-T Recommendation X.683 (1997) | ISO/IEC 8824-4:1998, Information Technology - Abstract Syntax Notation One (ASN.1): Parameterization of ASN.1 Specifications. [14] ITU-T Recommendation X.690 (1997) | ISO/IEC 8825-1:1998, Information Technology - ASN.1 Encoding Rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER). E. Contact Information & About PKCS The Public-Key Cryptography Standards are specifications produced by RSA Laboratories in cooperation with secure systems developers worldwide for the purpose of accelerating the deployment of public- key cryptography. First published in 1991 as a result of meetings with a small group of early adopters of public-key technology, the PKCS documents have become widely referenced and implemented. Contributions from the PKCS series have become part of many formal and de facto standards, including ANSI X9 documents, PKIX, SET, S/MIME, and SSL. Nystrom & Kaliski Informational [Page 12]
RFC 2986 Certification Request Syntax Specification November 2000 Further development of PKCS occurs through mailing list discussions and occasional workshops, and suggestions for improvement are welcome. For more information, contact: PKCS Editor RSA Laboratories 20 Crosby Drive Bedford, MA 01730 USA pkcs-editor@rsasecurity.com http://www.rsasecurity.com/rsalabs/pkcs Nystrom & Kaliski Informational [Page 13]
RFC 2986 Certification Request Syntax Specification November 2000
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