Abstract: A delegation-by-certificate proxy signature scheme and an ID-based proxy signature scheme are proposed under assumption of a factorization problem.The new schemes have such desirable features as strong un-forgeability and nonrepudiation, distinguishability, verifiability, identity confirmation of original and proxy signers, and revocability of the proxy signature delegation.The ID-based proxy signature scheme overcomes the limitation of some existing schemes that do not include ID information of signer and proxy signers.The proposed schemes allow online signature of the original signer, and are simple and efficient, and capable of resisting existing attacks.These schemes can be used in distributed computing, mobile agent, e-commerce and e-government systems.

Key words: proxy signature, ID-based proxy signature, delegation-by-certificate