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:

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.