Long-Term Archive and Notary Services
charter-ietf-ltans-03

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
period
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
expire,
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
certificate
and expiry of trusted time stamp authority certificate. A single
timestamp is not sufficient for this purpose. Additionally, the
reliable
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,
data
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
accordingly.

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
example,
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.