Special Aspects of Escrow-based E-Cash Systems
Lennart Meier
Electronic cash systems are one way to implement digital payments; e-cash
schemes can offer user anonymity at the same level as paper-based cash.
However, this anonymity can be misused for illegal purposes; therefore, some
means to revoke the anonymity under specific circumstances seems desirable.
Many ``escrow-based'' schemes have been proposed; the information needed for
this is usually escrowed at a trusted third party. In this thesis, we'll take
a close look at various escrow-based e-cash schemes and investigate their
security for all participants and the assumptions it is based on. The notion
of ``self-escrowing'', i.e. replacing the trusted third party by the user
himself, will be addressed; finally, by combining some of the techniques
presented, we construct an escrow-based e-cash scheme which offers
strengthened security against forgery of coins.