Using the Server-Based Certificate Validation Protocol (SCVP) to Convey Long-Term Evidence Records
RFC 5276

Network Working Group                                         C. Wallace
Request for Comments: 5276                            Cygnacom Solutions
Category: Standards Track                                    August 2008

   Using the Server-Based Certificate Validation Protocol (SCVP) to
                   Convey Long-Term Evidence Records

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Abstract

   The Server-based Certificate Validation Protocol (SCVP) defines an
   extensible means of delegating the development and validation of
   certification paths to a server.  It can be used to support the
   development and validation of certification paths well after the
   expiration of the certificates in the path by specifying a time of
   interest in the past.  The Evidence Record Syntax (ERS) defines
   structures, called evidence records, to support the non-repudiation
   of the existence of data.  Evidence records can be used to preserve
   materials that comprise a certification path such that trust in the
   certificates can be established after the expiration of the
   certificates in the path and after the cryptographic algorithms used
   to sign the certificates in the path are no longer secure.  This
   document describes usage of the SCVP WantBack feature to convey
   evidence records, enabling SCVP responders to provide preservation
   evidence for certificates and certificate revocation lists (CRLs).

Wallace                     Standards Track                     [Page 1]
RFC 5276               Evidence Records via SCVP             August 2008

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Requirements Notation  . . . . . . . . . . . . . . . . . .  3
   2.  Concept of Operations  . . . . . . . . . . . . . . . . . . . .  4
   3.  Requests . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
   4.  Responses  . . . . . . . . . . . . . . . . . . . . . . . . . .  6
   5.  WantBacks  . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     5.1.  Evidence Record for a Complete Certification Path  . . . .  7
     5.2.  Evidence Record for a Partial Certification Path . . . . .  7
     5.3.  Evidence Record for a Public Key Certificate . . . . . . .  8
     5.4.  Evidence Record for Revocation Information . . . . . . . .  8
     5.5.  Evidence Record for Any replyWantBack  . . . . . . . . . .  8
     5.6.  Partial Certification Path . . . . . . . . . . . . . . . .  9
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 10
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 10
   Appendix A.  ASN.1 Module  . . . . . . . . . . . . . . . . . . . . 11

Wallace                     Standards Track                     [Page 2]
RFC 5276               Evidence Records via SCVP             August 2008

1.  Introduction

   Digital signatures are frequently verified using public key
   infrastructure (PKI) artifacts, including public key certificates and
   certificate revocation information.  Verifiers construct and validate
   certification paths from a public key certificate containing the
   public key used to verify the signature to a trusted public key.
   Construction of a certification path may require the acquisition of
   different types of information generated by multiple PKIs.  To verify
   digital signatures many years after signature generation, additional
   considerations must be addressed.  For example, some necessary PKI
   artifacts may no longer be available, some may have expired, and the
   cryptographic algorithms or keys used in generating digital
   signatures may no longer provide the desired degree of security.

   SCVP [RFC5055] provides a means of delegating certification path
   construction and/or validation to a server, including the ability to
   request the status of a certificate relative to a time in the past.
   SCVP does not define a means of providing or validating long-term
   non-repudiation information.  ERS [RFC4998] defines a syntax for
   preserving materials over long periods of time through a regimen that
   includes periodic re-signing of relevant materials using newer keys
   and stronger cryptographic algorithms.  LTAP [LTANS-LTAP] defines a
   protocol for communicating with a long-term archive (LTA) server for