ANSI X9.95 and timestamping profile

["Dimitri Andivahis" <dimitri@surety.com>]

The ANSI X9.95 timestamping document describes a process 
for a requestor to renew an existing timestamp token for a given document.
As part of it, the requestor submits a timestamp request to the TSA 
for the given document and includes (in a request extension) 
the previously issued timestamp token.  The new timestamp token issued 
by the timestamping service encapsulates the previously issued timestamp 
token by including it in an extension of the TSTInfo.

The DSS timestamping profile specifies that the client submitting 
a sign request can only send <dss:DocumentHash> input documents and must not 
send <dss:Document> input documents.  It also specifies that the client 
may send the <dss:SignatureType> optional input, and no other optional inputs 
are supported.  

An X9.95 specific sub-profile of the timestamping profile could add 
renewal support in sign request by supporting some new optional input 
whose value would be a <dss:Timestamp>.  Alternatively, the previously 
existing timestamp token could be submitted in a SignedProperties optional input.  
I was wondering though if support for the mechanics of timestamp renewal 
should be folded into the timestamping profile itself, since it appears 
to be a generic enough operation for all types of timestamp tokens.

Dimitri