Network Working Group                                           C. AdamsRequest for Comments: 3029                          Entrust TechnologiesCategory: Experimental                                      P. Sylvester                                     EdelWeb SA - Groupe ON-X Consulting                                                            M. Zolotarev                                      Baltimore Technologies Pty Limited                                                           R. Zuccherato                                                    Entrust Technologies                                                           February 2001                Internet X.509 Public Key Infrastructure           Data Validation and Certification Server ProtocolsStatus of this Memo   This memo defines an Experimental Protocol for the Internet   community.  It does not specify an Internet standard of any kind.   Discussion and suggestions for improvement are requested.   Distribution of this memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2001).  All Rights Reserved.Abstract   This document describes a general Data Validation and Certification   Server (DVCS) and the protocols to be used when communicating with   it.  The Data Validation and Certification Server is a Trusted Third   Party (TTP) that can be used as one component in building reliable   non-repudiation services.   Useful Data Validation and Certification Server responsibilities in a   PKI are to assert the validity of signed documents, public key   certificates, and the possession or existence of data.   Assertions created by this protocol are called Data Validation   Certificates (DVC).   We give examples of how to use the Data Validation and Certification   Server to extend the lifetime of a signature beyond key expiry or   revocation and to query the Data Validation and Certification Server   regarding the status of a public key certificate.  The document   includes a complete example of a time stamping transaction.Adams, et al.                 Experimental                      [Page 1]RFC 3029                     DVCS Protocols                February 2001Table of Contents   1. Introduction .................................................  2   2. Services provided by DVCS ....................................  4    2.1 Certification of Possession of Data ........................  4    2.2 Certification of Claim of Possession of Data ...............  4    2.3 Validation of Digitally Signed Documents ...................  4    2.4 Validation of Public Key Certificates ......................  5   3. Data Certification Server Usage and Scenarii .................  5   4. Functional Requirements for DVCS .............................  7   5. Data Certification Server Transactions .......................  7   6. Identification of the DVCS ...................................  8   7. Common Data Types ............................................  9    7.1 Version ....................................................  9    7.2 DigestInfo ................................................. 10    7.3. Time Values ............................................... 10    7.4. PKIStatusInfo ............................................. 11    7.5. TargetEtcChain ............................................ 11    7.6. DVCSRequestInformation .................................... 12    7.7. GeneralName and GeneralNames .............................. 13   8. Data Validation and Certification Requests ................... 13   9. DVCS Responses ............................................... 17    9.1. Data Validation Certificate ............................... 18    9.2. DVCS Error Notification ................................... 21   10. Transports .................................................. 22    10.1 DVCS Protocol via HTTP or HTTPS ........................... 22    10.2 DVCS Protocol Using Email ................................. 22   11. Security Considerations ..................................... 23   12. Patent Information .......................................... 23   13. References .................................................. 25   14. Authors' Addresses .......................................... 26   APPENDIX A - PKCS #9 Attribute .................................. 27   APPENDIX B - Signed document validation ......................... 27   APPENDIX C - Verifying the Status of a Public Key Certificate ... 28   Appendix D - MIME Registration .................................. 30   Appendix E - ASN.1 Module using 1988 Syntax ..................... 31   Appendix F - Examples ........................................... 34   Appendix G - Acknowledgements ................................... 50   Full Copyright Statement ........................................ 511. Introduction   This document is the result of work that has been proposed and   discussed within the IETF PKIX working group.  The authors and some   members of the group felt that promoting the rather new concepts into   the standards process seemed premature.  The concepts presented have   been stable for some time and partially implemented.  It was agreed   that a publication as experimental RFC was an appropriate means toAdams, et al.                 Experimental                      [Page 2]RFC 3029                     DVCS Protocols                February 2001   get a stable reference document to permit other implementations to   occur.   The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",   "RECOMMENDED", "MAY", and "OPTIONAL" in this document (in uppercase,   as shown) are to be interpreted as described in [RFC2119].   A Data Validation and Certification Server (DVCS) is a Trusted Third   Party (TTP) providing data validation services, asserting correctness   of digitally signed documents, validity of public key certificates,   and possession or existence of data.   As a result of the validation, a DVCS generates a Data Validation   Certificate (DVC).  The data validation certificate can be used for   constructing evidence of non-repudiation relating to the validity and   correctness of an entity's claim to possess data, the validity and   revocation status of an entity's public key certificate and the   validity and correctness of a digitally signed document.   Services provided by a DVCS do not replace the usage of CRLs and OCSP   for public key certificate revocation checking in large open   environments, due to concerns about the scalability of the protocol.   It should be rather used to support non-repudiation or to supplement   more traditional services concerning paperless document environments.   The presence of a data validation certificate supports   non-repudiation by providing evidence that a digitally signed   document or public key certificate was valid at the time indicated in   the DVC.   A DVC validating a public key certificate can for example be used   even after the public key certificate expires and its revocation   information is no longer or not easily available.  Determining the   validity of a DVC is assumed to be a simpler task, for example, if   the population of DVCS is significantly smaller than the population   of public key certificate owners.   An important feature of the protocol is that DVCs can be validated by   using the same protocol (not necessarily using the same service), and   the validity of a signed document, in particular a DVC, can also be   determined by means other than by verifying its signature(s), e.g.,   by comparing against an archive.   The production of a data validation certificate in response to a   signed request for validation of a signed document or public key   certificate also provides evidence that due diligence was performed   by the requester in validating a digital signature or public key   certificate.Adams, et al.                 Experimental                      [Page 3]RFC 3029                     DVCS Protocols                February 2001   This document defines the use of digital signatures to insure the   authenticity of documents and DVCs, and uses a corresponding   terminology; the use of other methods to provide evidence for   authenticity is not excluded, in particular it is possible to replace   a SignedData security envelope by another one.2. Services provided by DVCS   The current specification defines 4 types of validation and   certification services:   - Certification of Possession of Data (cpd),   - Certification of Claim of Possession of Data (ccpd),   - Validation of Digitally Signed Document (vsd), and   - Validation of Public Key Certificates (vpkc).   A DVCS MUST support at least a subset of these services.  A DVCS may   support a restricted vsd service allowing to validate data validation   certificates.   On completion of each service, the DVCS produces a data validation   certificate - a signed document containing the validation results and   trustworthy time information.2.1 Certification of Possession of Data   The Certification of Possession of Data service provides evidence   that the requester possessed data at the time indicated and that the   actual data were presented to the Data Validation Server.2.2 Certification of Claim of Possession of Data   The Certification of Claim of Possession of Data service is similar   to the previous one, except that the requester does not present the   data itself but a message digest.2.3 Validation of Digitally Signed Documents   The Validation of Digitally Signed Document service is used when   validity of a signed document is to be asserted.   The DVCS verifies all signatures attached to the signed document   using all appropriate status information and public key certificates.   The DVCS verifies the mathematical correctness of all signatures   attached to the document and also checks whether the signing entities   can be trusted, for example by validating the full certification path   from the signing entities to a trusted point (e.g., the DVCS's CA, or   the root CA in a hierarchy).Adams, et al.                 Experimental                      [Page 4]RFC 3029                     DVCS Protocols                February 2001   The DVCS may be able to rely on relevant CRLs or may need to   supplement this with access to more current status information from   the CAs for example by accessing an OCSP service, a trusted directory   service, or other DVCS services.   The DVCS will perform verification of all signatures attached to the   signed document.  A failure of the verification of one of the   signatures does not necessarily result in the failure of the entire   validation, and vice versa, a global failure may occur if the   document has an insufficient number of signatures.2.4 Validation of Public Key Certificates   The Validation of Public Key Certificates service is used to verify   and assert the validity (according to [RFC2459]) of one or more   public key certificates at the specified time.   When verifying a public key certificate, the DVCS verifies that the   certificate included in the request is a valid certificate and   determines its revocation status at a specified time.  DVS checks the   full certification path from the certificate's issuer to a trusted   point.  Again, the DVCS MAY be able to rely on external information   (CRL, OCSP, DVCS).3. Data Certification Server Usage and Scenarii.   It is outside the scope of this document to completely describe   different operational scenarii or usages for DVCS.   See Appendix B and C for a set of some basic examples and use cases.   The Validate Signed Document service can be used to support non-   repudiation services, to allow use of the signed document beyond   public key certificate revocation or expiry, or simply to delegate   signature validation to a trusted central (company wide) service.   The Validate Public Key Certificate service can be used when timely   information regarding a certificate's revocation status is required   (e.g., high value funds transfer or the compromise of a highly   sensitive key) or when evidence supporting non-repudiation is   required.   A data validation certificate may be used to simplify the validation   of a signature beyond the expiry or subsequent revocation of the   signing certificate: a Data validation certificate used as an   authenticated attribute in a signature includes an additionalAdams, et al.                 Experimental                      [Page 5]RFC 3029                     DVCS Protocols                February 2001   assertion about the usability of a certificate that was used for   signing.  In order to validate such a signature it may be sufficient   to only validate the data validation certificate.   A DVCS may include additional key exchange certificates in a data   validation certificate to validate a key exchange certificate in   order to provide to an application a set of additional authorised   recipients for which a session key should also be encrypted.  This   can be used for example to provide central management of a company   wide recovery scheme.  Note, that the additional certificates may not   only depend on the requested certificate, but also on the requester's   identity.   The Certification of Claim of Possession of Data service is also   known as time stamping.   The Certification of Possession of Data service can be used to assert   legal deposit of documents, or to implement archival services as a   trusted third party service.   The Data Validation and Certification Server Protocols can be used in   different service contexts.  Examples include company-wide   centralised services (verification of signatures, certification of   company certificates), services to cooperate in a multi-organization   community, or general third party services for time stamping or data   archival.   An important application of DVCS is an enterprise environment where   all security decisions are based on company wide rules.  A company   wide DVCS service can be used to delegate all technical decisions   (e.g., path validation, trust configuration) to a centrally managed   service.   In all cases, the trust that PKI entities have in the Data Validation   and Certification Server is transferred to the contents of the Data   Validation Certificate  (just as trust in a CA is transferred to the   public key certificates that it issues).   A DVCS service may be combined with or use archiving and logging   systems, in order to serve as a strong building block in non-   repudiation services.  In this sense it can be regarded as an   Evidence Recording Authority [ISO-NR].Adams, et al.                 Experimental                      [Page 6]RFC 3029                     DVCS Protocols                February 2001