RE: [dss] Timestamping

[Karel Wouters <Karel.Wouters@esat.kuleuven.ac.be>]

Dimitri,

thanks for the clear text. Something like this should be included in the
ISO document itself. (atmof, why didn't you include it ?)

I have some remarks/questions:
You say:
> In all linking schemes, simple or accumulated, if the verification
> result code is success, the timestamp is proved to
> have participated in the linking operation of the TSA
> at the time value included in the token itself.

doesn't this ignore the more powerful functionality of linking schemes?
What you define here is linking schemes with absolute temporal
authentication.
Some authors of linking schemes have an entirely different approach:
linking schemes are to be used for _relative_ temporal authentication,
meaning that you can only compare two time-stamps. Moreover, absolute time
indications can be inaccurate. A TSA could, for example, stop issuing
time-stamps for an hour, and then continue with time-stamps backdated by
an hour.

Just wondering, because some of those schemes (Lipmaa, Buldas et al. )
also fit into the ISO 18014-3 FCD.

Also, what about the patents by Surety on these schemes?
(or: what are the "openly specified, reasonable, non-discriminatory
terms." of Surety about this?)

Karel.