Citation: Trustee Tokens: Simple and Practical Tracing of Anonymous Digital Cash. In R. Hirschfeld, editor, Financial Cryptography '99, pages 29-45, Springer-Verlag, 1999. LNCS No. 1648.
Abstract: We introduce a trustee-based tracing mechanism for
anonymous digital cash that is simple, efficient, and provably secure
relative to its underlying cryptographic primitives. In contrast to
previous schemes, ours may be built on top of a real-world anonymous
cash system, such as the DigiCash (TM) system, with minimal modification
to the underlying protocols. In addition, our scheme involves no change
to the structure of the coins. On the other hand, our scheme requires
user interaction with a trustee, while many other such systems do not.
This interaction occurs infrequently, however, and is efficient both
in terms of computation and storage requirements. Our scheme also achieves
more limited security guarantees in the presence of malicious trustees
than many other systems do. While this is a disadvantage, it represents
a tradeoff enabling us to achieve the high level of practicality of