The Sanctuary project at UCSD is building a secure infrastructure for mobile agents, and examining

We show here an example of a protocol that satis es anonymity properties while providing strong ACID (atomic, consistent, isolated, durable) transactional properties, resolving an open question. Blinded signatures are used to certify an anonymous asymmetric key which authorizes the use of a speci ed value. A public transaction log is used to support a linear commitment scheme for transactions in which the value authorized by the blind signed key is spent.

The timestamping problem is one of showing that one possessed a document before a certain time. In this paper several protocols are discussed for solving this problem. These protocols were developed by Haber and Stornetta [11] and by Benaloh and de Mare [5, 6]. In addition, this paper discusses the Byzantine Generals' Problem, which is necessary for the protocols to operate and discusses the relative strength of the protocols and ways to avoid certain types of attacks.

. We present a related family of authentication and digital signature protocols based on symmetric cryptographic primitives which perform substantially better than previous constructions. Previously, one-time digital signatures based on hash functions involved hundreds of hash function computations for each signature; we show that given online access to a timestamping service, we can sign messages using only two computations of a hash function. Previously, techniques to sign infinite streams involved one such one-time signature for each message block; we show that in many realistic scenarios a small number of hash function computations is sufficient. Previously, the Diffie Hellman protocol enabled two principals to create a confidentiality key from scratch: we provide an equivalent protocol for integrity, which enables two people who do not share a secret to set up a securely serialised channel into which attackers cannot subsequently intrude. In addition to being of potential ...

this document is being circulated for STUDY AND COMMENT by 2000-09-20.