Digital signatures are a basic technology for secure e-business, but only if the following issues are addressed, so that relying parties can trust in digitally signed statements.
One problem area is the validation of digital signatures. It cannot be guaranteed that the result is independent of the time of checking. Similarly, it is not clear whether the validity of digital signatures can be checked at any future time. Moreover, the delivery risks of digitally signed messages are not distributed according to the responsibilities of sender and recipient.
For these reasons, alternative and more comprehensive solutions are necessary. One area is to support that declarations of intent become binding at a point in time that is fair towards both the signer and the verifier.
This talk is based on problems and experiences with digital signatures analysed in the context of the German Digital Signature Act and Ordinance. It should be interesting to discuss some of these proposals in a European context.