Improved Signcryption Scheme with Public Verifiability

Signcryption scheme can achieve signature authentication and encryption transmission simultaneously in a single protocol, it effectively prevents mutual cheating in message transmission. In the paper, we analyzed the security threats and system flaws of present signcryption schemes, and presented an improved signcryption scheme with public verifiability based on ECC (elliptic curves cryptosystem). The scheme achieves public verification of signcryption by TTP (trustable third party) without disclosing private key or secret parameters. The scheme avoids the illegal refusal of valid signcryption by TTP, effectively prevents generalized signcryption forgery and coalition attack by message receiver and outer adversaries. The one-way trapdoor function is based on ECDLP (elliptic curves discrete logarithm problem), so the algorithms of the scheme take great advantage of the superiority of ECC, such as high efficiency, short key length and etc. The scheme not only reinforces the security and stability of signcryption but also effectively improves the efficiency of signcryption for software and hardware application.