This paper presents a novel method that allows the delegation of signature power to one or more entities that jointly play the role of a proxy signer. This work is different from other related proxy signature schemes in that in addition to providing confidentiality protection to the proxy key, the method provides non-repudiation services to all the parties involved. In particular, it protects against repudiation of signature delegation by the original signer, repudiation of proxy signature generation by the proxy signer, and repudiation of receipt of the proxy signature by the signature recipient. This feature is attractive for signature delegation in agent-based paradigm in which proxy signers are mobile agents that are executed in remote untrustworthy hosts. Categories and Subject Descriptors K.4.4 [Computer and Society]: Electronic Commerce – distributed commercial transactions, security, mobile code security. General Terms Security. Keywords mobile agent security; signature dele...