2.7.8 Long-Term Archive and Notary Services (ltans)

NOTE: This charter is a snapshot of the 64th IETF Meeting in Vancouver, British Columbia Canada. It may now be out-of-date.

Last Modified: 2005-09-27


Carl Wallace <cwallace@orionsec.com>
Tobias Gondrom <tobias.gondrom@opentext.com>

Security Area Director(s):

Russ Housley <housley@vigilsec.com>
Sam Hartman <hartmans-ietf@mit.edu>

Security Area Advisor:

Russ Housley <housley@vigilsec.com>

Mailing Lists:

General Discussion: ietf-ltans@imc.org
To Subscribe: ietf-ltans-request@imc.org
In Body: subscribe
Archive: http://www.imc.org/ietf-ltans

Description of Working Group:

In many scenarios, users need to be able to ensure and prove the
existence and validity of data, especially digitally signed data, in a
common and reproducible way over a long and possibly undetermined
of time.

Cryptographic means are useful, but they do not provide the whole
solution. For example, digital signatures (generated with a particular
key size) might become weak over time due to improved computational
capabilities, new cryptanalytic attacks might "break" a digital
signature algorithm, public key certificates might be revoked or
and so on.

Complementary methods covering potential weaknesses are necessary.

Long-term non-repudiation of digitally signed data is an important
aspect of PKI-related standards. Standard mechanisms are needed to
handle routine events, such as expiry of signer's public key
and expiry of trusted time stamp authority certificate. A single
timestamp is not sufficient for this purpose. Additionally, the
preservation of content across change of formats, application of
electronic notarizations, and subsequent notary services require
standard solutions.

The objective of the LTANS working group is to define requirements,
structures and protocols for the secure usage of the necessary archive
and notary services. First, the requirements for the long-term archive
will be collected. Based on that information we will develop a protocol
to access archive services supplying long-term non-repudiation for
signed documents and define common data structures and formats. Upon
completion of the archive-related specifications, we will address
'notary services' in a similar way. The term 'notary services' is not
clearly defined. The working group will determine which functions need
standards, including transformation of documents from one format to
another without losing the value of evidence, electronic notarization,
and further verification of legal validity of signed documents. We will
determine the needs via the requirements paper and act upon the results

Work done by the IETF Working Groups PKIX, S/MIME and XMLDSIG will be
used as the basis to define those structures and protocols. For
the Internet-Drafts "Archive Time-Stamps Syntax (ATS)" and "Trusted
Archive Protocol (TAP)" and RFC 3029, "Data Validation and Certificate
Server Protocols (DVCS)", contain applicable concepts.

Goals and Milestones:

Done  Initial requirements for long-term archive I-D
Done  Initial data structures for long-term archive I-D
Done  Revised requirements for long-term archive I-D
Done  Revised data structures for long-term archive I-D
Done  Initial requirements for notary services I-D
Done  Initial protocol for long-term archive I-D
Done  Revised requirements for notary services I-D
Sep 2005  WG Last call data structures for long-term archive I-D
Oct 2005  WG Last call requirements for long-term archive I-D
Nov 2005  Submit requirements for long-term archive to IESG as informational
Nov 2005  Submit data structures for long-term archive to IESG as proposed standard
Dec 2005  Protocol revisions for long-term archive I-D
Jan 2006  WG Last call protocol for long-term archive I-D
Jan 2006  Submit protocol for long-term archive to IESG as proposed standard
Jan 2006  WG Last call requirements for notary services I-D
Jan 2006  Submit requirements for notary services to IESG as informational
Mar 2006  Recharter or close the working group


  • draft-ietf-ltans-reqs-05.txt
  • draft-ietf-ltans-ers-03.txt
  • draft-ietf-ltans-notareqs-02.txt
  • draft-ietf-ltans-ltap-00.txt
  • draft-ietf-ltans-ers-scvp-00.txt

    No Request For Comments

    Current Meeting Report

    LTANS WG meeting 11/7/2005
    Approximately 20 people attended the meeting
    Intro (slides: 1 - LTANS.ppt)
    The introduction consisted of a review of activities since the Paris meeting and a review of what needs to happen between now and the Dallas meeting.
    Two revised drafts were posted since Paris and 1 new draft was posted.  A new version of ERS was circulated shortly before the meeting today.
    Ideally, ERS will enter WG last call in later in November.  It was noted that an approach for LTAP as well as preservation of artifacts required to verify EvidenceRecords must be decided upon.  
    Notary requirements (slides: 2 - ltans-notary-req-review.pdf)
    Wolfgang Schneider led a discussion on the notarization requirements.  The current requirements are very generic and need to be made more concrete.
    Document transformations are a fundamental concern.  The goal is to ensure that transformed documents maintain the same semantics as the original and to provide assertions to this fact.  The requirements are lacking in specifics on roles and processes required to attest to document equivalence.
    The current data integrity requirements may be sufficient.  The requirements are lacking in the area of accountability, e.g., logging.  Data structures must be defined to establish the context in which document equivalence was determined.  
    The next steps will be to update the requirements document to establish more concrete requirements and to release a specification describing data structures that satisfy those requirements.  Wolfgang indicated that Andreas is working with Tobias and Larry on the revised document.  No questions or comments were raised during the presentation.
    SCVP/ERS I-D (slides: 3 - Using SCVP to Convey Evidence Records.ppt)
    The concept underlying the "Using SCVP to Convey Evidence Records" draft was described.  Several issues were presented.  No questions or comments were raised during the presentation.  Results of a sidebar discussion after the meeting were posted to the mailing list.
    ERS (slides: 4 - ERS.ppt and 4a - ltans-ers.ppt)
    Two sets of slides were presented discussing the current ERS status.  A new draft was released a few hours before the meeting to address several comments made on the mailing list including modifications to the ASN.1 module and clarification of some language throughout the doc (e.g., capitalizing some MUSTs and SHOULDs).  References to X9.95 and ISO timestamp specifications were added to the document to permit usage of timestamps other than RFC3161 timestamps.
    Tobias would like to progress ERS to last call during November.  A few issues potentially related to ERS were raised and should be further discussed on the list (e.g., lack of extensibility mechanisms and lack of means to convey policy information).  No questions or comments were raised during the presentation.
    Shoring up hash algorithms (slides: 5 - hash-ltans.ppt)
    Slides further describing Santosh's recent email to the list describing an approach to strengthen usage of hash algorithms were presented.  The applicability of these techniques and other randomized hash techniques to the long-term archive problem should be explored.  For some types of documents, application of these techniques may obviate the need to perform periodic preservation activities.  No questions or comments were raised during the presentation.
    Action items are as follows:
    	Andreas, Larry and Tobias: revise notary requirements document
    	Wolfgang, Andreas: prepare and circulate specification describing data structures to satisfy notary requirements
    	Peter, Aleksej, Carl: prepare and circulate concrete LTAP specification
    	Group: review SCVP/ERS draft and determine if it should be carried forward as a WG draft
    	Group: review -04 draft of ERS in preparation for last call
    	Tobias, Ulrich, Ralf: Response to group comments during ERS last call


    Long-term Archive and Notary Services (LTANS) Working Group Introduction
    Notary Services Requirements Review
    Using SCVP to Convey Evidence Records
    ERS Status Part 1
    ERS Status Part 2
    Shoring Up Hash Algorithms