Latest ETSI standard CAdES, XAdES and PAdES require for baseline profile LTA
to fulfill previous LT
, T
and B
levels. Summarizing,the conformance requirements are:
- B : Base signature with content-type, signing-time and signing-certificate
- T: Signature timestamp
- LT: Certificate and revocation values
- LTA: Archive timestamp
More or less are simplifications over the previous BES
, EPES
, T
, XL
, and A
levels, where the requirement is also present
Applying a timestamp is an expensive process in time and money, because it is usually performed by an external trusted CA
Question: What is the reason for applying two time stamps when building an LTA directly, bearing in mind that the last time stamp protects all content? Why -T
timestamp is not optional?