RFC2986
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.
Contents
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]).
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
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.
2.2 Notation
No special notation is used in this document.
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.
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.
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 SubjectPublicKeyInfoTemplate:PKInfoAlgorithms,
attributes [0] AttributesTemplate:CRIAttributes
}
SubjectPublicKeyInfo { ALGORITHM : IOSet} ::= SEQUENCE {
algorithm AlgorithmIdentifier Template:IOSet, subjectPublicKey BIT STRING
}
PKInfoAlgorithms ALGORITHM ::= {
... -- add any locally defined algorithms here -- }
Attributes { ATTRIBUTE:IOSet } ::= SET OF AttributeTemplate: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
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 AlgorithmIdentifierTemplate: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.
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
}
Security Considerations
Security issues are discussed throughout this memo.
Authors' Addresses
Magnus Nystrom RSA Security Box 10704 S-121 29 Stockholm Sweden
EMail: [email protected]
Burt Kaliski RSA Security 20 Crosby Drive Bedford, MA 01730 USA
EMail: [email protected]
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 SubjectPublicKeyInfoTemplate:PKInfoAlgorithms,
attributes [0] AttributesTemplate:CRIAttributes
}
SubjectPublicKeyInfo {ALGORITHM: IOSet} ::= SEQUENCE {
algorithm AlgorithmIdentifier Template:IOSet, subjectPublicKey BIT STRING
}
PKInfoAlgorithms ALGORITHM ::= {
... -- add any locally defined algorithms here -- }
Attributes { ATTRIBUTE:IOSet } ::= SET OF AttributeTemplate: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})
}
CertificationRequest ::= SEQUENCE {
certificationRequestInfo CertificationRequestInfo,
signatureAlgorithm AlgorithmIdentifierTemplate: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]).
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.
[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.
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
[email protected]
http://www.rsasecurity.com/rsalabs/pkcs
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