PKIX Working Group D. Pinkas (Bull) INTERNET-DRAFT T. Gindin (IBM) Expires: February, 2001 August, 2000 Target category: Standard Track Internet X.509 Public Key Infrastructure Permanent Identifier Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of [RFC 2026]. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Copyright (C) The Internet Society (2000). All Rights Reserved. Abstract This document define a new form of name, called permanent identifier, that may be included in the subjectAltName extension of a public key certificate issued to a physical person. The permanent identifier is an optional feature that may be used by a CA to indicate that the certificate relates to the same individual even if the name or the affiliation of that individual has changed. The subject name when carried in the subject field is only unique for each subject entity certified by the one CA as defined by the issuer name field. This new form of name also allows to carry a name that is unique for each subject entity certified by any CA. 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 RFC 2119. Please send comments on this document to the ietf-pkix@imc.org mailing list. Pinkas, Gindin [ Page 1] Permanent Identifier Document Expiration: February 2001 1 Introduction This specification is one part of a family of standards for the X.509 Public Key Infrastructure (PKI) for the Internet. It is based on RFC 2459, which defines underlying certificate formats and semantics needed for a full implementation of this standard. The subject field of a public key certificate identifies the entity associated with the public key stored in the subject public key field. The subject name may be carried in the subject field and/or the subjectAltName extension. Where it is non-empty, the subject field MUST contain an X.500 distinguished name (DN). The DN MUST be unique for each subject entity certified by the one CA as defined by the issuer name field. The subject name changes as soon as one of the components of that name gets changed. There are several reasons for this change to happen. For companyÆs or organizationÆs employees, the person may get a different position within the same company and thus will move from an organization unit to another one. Including the organisation unit in the name may however be very useful to allow the relying parties (RPs) using that certificate to identify the right individual. For citizens, an individual may change their name by legal processes, especially women as a result of marriage. A permanent identifier may be useful both in the context of access control and of non repudiation. For access control, the permanent identifier may be used in an ACL (Access Control List) instead of the DN or any other form of name and would not need to be changed, even if the subject name of the individual changes. For non-repudiation, the permanent identifier may be used to link different transactions to the same individual, even when the subject name of the individual changes. When two certificates from the same CA contain the same permanent identifier, then these certificates relate to the same individual. 2. Definition A permanent identifier is a name assigned by an organization, unique within that organization, that singles out a particular individual from all other individuals. A CA which includes such an identifier in a certificate is certifying that any different public key certificate containing that identifier refers to the same individual. Pinkas, Gindin [ Page 2] Permanent Identifier Document Expiration: February 2001 The use of a permanent identifier is optional. This name is defined as a form of otherName from the GeneralName structure in SubjectAltName. The permanent identifier is defined as follows: id-on-permanentIdentifier AttributeType ::= { id-on 2 } PermanentIdentifier ::= SEQUENCE { assignerAuthority GeneralName OPTIONAL, identifier Name } The assignerAuthority field of this attribute, when present, identifies the organization responsible for assigning the content of the identifier field. When the assignerAuthority field is missing, the assigner Authority is the CA itself and it is assumed to be the issuer name of the certificate. Two forms of names are supported for the assignerAuthority. That field may either contain a directoryName (which is a Name) or a registeredID (which is an OID). If, directoryName is used, then the permanent identifier is locally unique to the CA. The CA must locally make ensure that that, once assigned, a name for an assignerAuthority is never re-used. If, registeredID is used, then the permanent identifier is globally unique to all CAs (i.e. the same OID can never be re-used). The identifier field may contain any series of directory attributes. In particular, it may contain a serialNumber attribute. A serialNumber attribute may be used for two different purposes in the DN of a person: 1) In a DN or a SubjectAltName to differentiate between two names (for two different individuals) that otherwise would not be different. 2) In the identifier field from a permanent identifier. This is the recommended use for national ID's and employee ID's, for example. Note: the full arc of the object identifier is derived using: id-pkix OBJECT IDENTIFIER ::= { iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) } id-on OBJECT IDENTIFIER ::= { id-pkix 8 } -- other name forms 3. Security considerations A given individual may have at an instant of time or at different instants of time multiple forms of identities. Pinkas, Gindin [ Page 3] Permanent Identifier Document Expiration: February 2001 If the permanent identifier is locally unique to the CA (i.e. in GeneralName from AssignerAuthority, directoryName is used), then two certificates from the same CA can be compared. When they contain two identical permanentIdentifiers, then a relying party may determine that they refer to the same individual. If the permanent identifier is globally unique to all CAs (i.e. in GeneralName from AssignerAuthority, registeredID is used), then two certificates from different CAs are, can be compared. When they contain two identical permanentIdentifiers, then a relying party may determine that they refer to the same individual. When a permanent identifier is present in a public key certificate which contains attribute extensions, the permanent identifier should not be used for access control purposes. The reason is that since these attributes may change and the permanent identifier will not, the permanent identifier identifies the individual, irrespective of any attribute extension. 4. References [RFC 2026] S. Bradner, ôThe Internet Standards Process û Revision 3 ©, November 1996. [RFC 2119] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", March 1997. [RFC 2459] R. Housley, W. Ford, W. Polk, and D. Solo, "Internet X.509 Public Key Infrastructure: Certificate and CRL Profile", January 1999. [X.501] ITU-T Recommendation X.501 (1997 E): Information Technology - Open Systems Interconnection - The Directory: Models, June 1997. [X.509] ITU-T Recommendation X.509 (1997 E): Information Technology - Open Systems Interconnection - The Directory: Authentication Framework, June 1997. [X.520] ITU-T Recommendation X.520: Information Technology - Open Systems Interconnection - The Directory: Selected Attribute Types, June 1997. [X.680] ITU-T Recommendation X.680: Information Technology - Abstract Syntax Notation One, 1997. 5. AuthorÆs Addresses Denis Pinkas Bull S.A. 12 rue de Paris B.P. 59 78231 Le Pecq FRANCE Email: Denis.Pinkas@bull.net Pinkas, Gindin [ Page 4] Permanent Identifier Document Expiration: February 2001 Thomas Gindin IBM Corporation 6710 Rockledge Drive Bethesda, MD 20817 USA Email: tgindin@us.ibm.com 6 Intellectual Property Rights The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. Pinkas, Gindin [ Page 5] Permanent Identifier Document Expiration: February 2001 APPENDIX ASN.1 definitions A.1 1988 ASN.1 Module PKIXpermanentidentifier88 {iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) id-mod(0) id-mod-permanent-identifier-88(14) } DEFINITIONS EXPLICIT TAGS ::= BEGIN -- EXPORTS ALL -- IMPORTS id-pkix, AttributeType, Name, GeneralName 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)} GeneralName FROM PKIX1Implicit88 {iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-implicit-88(2)}; -- Object Identifiers -- Externally defined OIDs -- Arc for other name forms id-on OBJECT IDENTIFIER ::= { id-pkix 8 } -- permanent identifier id-on-permanentIdentifier AttributeType ::= { id-on 2 } PermanentIdentifier ::= SEQUENCE { assignerAuthority GeneralName OPTIONAL, identifier Name } END Pinkas, Gindin [ Page 6] Permanent Identifier Document Expiration: February 2001 A.2 1993 ASN.1 Module PKIXpermanentidentifier93 {iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) id-mod(0) id-mod-permanent-identifier-93(15) } DEFINITIONS EXPLICIT TAGS ::= BEGIN -- EXPORTS ALL -- IMPORTS GeneralName FROM PKIX1Implicit93 {iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-implicit-93(4)} id-pkix, ATTRIBUTE, Name FROM PKIX1Explicit93 {iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-explicit-93(3)}; -- Object Identifiers -- Externally defined OIDs -- Arc for other name forms id-on OBJECT IDENTIFIER ::= { id-pkix 8 } -- Locally defined OIDs id-on-permanentIdentifier OBJECT IDENTIFIER ::= { id-on 2 } -- permanent identifier permanentIdentifier ATTRIBUTE ::= { WITH SYNTAX PermanentIdentifier, ID id-on-permanentIdentifier } PermanentIdentifier ::= SEQUENCE { assignerAuthority GeneralName OPTIONAL, identifier Name } END Pinkas, Gindin [ Page 7] Permanent Identifier Document Expiration: February 2001 A3. OIDs for organizations There are various ways for a company to obtain an OID. In some cases, they are provided for free. In other cases a one-time fee is required. The main difference lies in the nature of the information that is collected at the time of registration and how this information is verified for its accuracy. A.3.1. Using IANA (Internet Assigned Numbers Authority) The application form for a Private Enterprise Number in the IANA's OID list is: http://www.iana.org/cgi-bin/enterprise.pl. Currently IANA assigns numbers for free. The IANA-registered Private Enterprises prefix is: iso.org.dod.internet.private.enterprise (1.3.6.1.4.1) These numbers are used, among other things, for defining private SNMP MIBs. The official assignments under this OID are stored in the IANA file "enterprise-numbers" available at: ftp://ftp.isi.edu/in-notes/iana/assignments/enterprise-numbers A.3.2. Using an ISO member body ISO has defined the OID structure in a such a way so that every ISO member-body has its own unique OID. Then every ISO member-body is free to allocate its own arc space below. Organizations and enterprises may contact the ISO member-body where their organization or enterprise is established to obtain an organization/enterprise OID. Currently, ISO members do not assign organization/enterprise OIDs for free. Most of them do not publish registries of such OIDs which they have assigned, sometimes restricting the access to registered organizations or preferring to charge inquirers for the assignee of an OID on a per-inquiry basis. The use of OIDs from an ISO member organization which does not publish such a registry may impose extra costs on the CA that needs to make sure that the OID corresponds to the registered organization. As an example, AFNOR (Association Francaise de Normalisation - the French organization that is a member of ISO) has defined an arc to allocate OIDs for companies: {iso (1) member-body (2) fr (250) type-org (1) organisation (n)} Pinkas, Gindin [ Page 8] Permanent Identifier Document Expiration: February 2001 E. 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. In addition, the ASN.1 modules presented in Appendices A and B may be used in whole or in part without inclusion of the copyright notice. 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 of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process shall 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. Pinkas, Gindin [ Page 9]