Paper 2004/142

Elliptic Curve based Signcryption and its Multi-party Schemes

Yiliang HAN and Xiaoyuan YANG

Abstract

Signcryption is a novel public key primitive to achieve the combined functionality of authentication and confidentiality in an efficient manner. A new Elliptic Curve Cryptosystems based Signcryption which combines ECDSA and PSCE-1 is presented in the paper. The signcryption scheme is a publicly verifiable scheme which can be verified by the third party after the specific recipient removes his key information. Analysis shows that the proposed scheme is secure against the adaptive chosen ciphertext attack. The signcryption saves the communication cost at least 1.25 times and enhances computation cost 1.19 times over ECDSA-then-PSCE-1. Compared with other signcryption schemes, such as Y.Zheng¡¯s ECSCS, the new signcryption uses a uniform elliptic curve cryptosystem platform instead of four kinds of cryptosystem components: hash function, keyed hash function, symmetric cipher and elliptic curve. While keeping high security and efficiency, the scheme can be implemented in software and hardware at low price because of above advantages. Base on the signcryption, a broadcast scheme for multiple recipients and a threshold scheme with key distributed generation for multiple senders are also proposed.

Note: We resised the original scheme because of its insecurity.