Offline Payments with Auditable Tracing

Auditable Envelopes: Tracking Anonymity Revocation Using Trusted Computing

“…We do not specifically address any of these areas, as the way in which they use the identity of the user is unimportant to us: it is the similarity in the need for the user's anonymity that matters. Very little existing work considers auditable revocable anonymity: Kugler and Vögt [11] discuss an electronic payment protocol in which the spender of a coin can determine (within a fixed period) whether their anonymity is revoked or not. Although the protocol is attractive, it requires knowledge a priori of who is to be traced-something which is not possible in fields such as electronic voting.…”

“…. the detectability of inappropriate actions and accountability for origination suffices to prevent misbehaviour from happening [22, p. 5] Though protocols exist in electronic commerce which permit this ( [11], for example), the techniques used are not widely applicable, for reasons discussed above. We consider preliminary discussions of "escrowed data" stored in a digital envelope which use monotonic counters [1], and discuss the use of virtual monotonic counters [14] to allow multiple tokens to be securely stored by a single entity.…”

Accountable Metadata-Hiding Escrow: A Group Signature Case Study

“…Interestingly there are e-cash schemes that hold the authority accountable [15,16]. Unfortunately, these schemes require interaction with the tracing authority for every transaction and, as a result, the techniques do not necessarily scale.…”

Remote Electronic Voting with Revocable Anonymity

“…In any case, no other protocol discusses revocable anonymity at all, to our knowledge. We note that revocable anonymity is a concept which has been considered at great length in other fields, such as digital cash [14,15,17].…”