Signcryption method with hidden identity and strong security

Abstract

The invention provides a signcryption method with hidden identity and strong security. The signcryption method comprises the steps that: a first device calculates X' = AXd, wherein X = gx and d = hd (X, auxd), determines a preset shared key S according to a DH-index x, a private key a and a public key B = gb of a second device, determines KA based on S, determines CA = (IA, A, CERTA, X, DataA)) according to KA, and sends [X CA]' to the second device; the second device determines the preset shared key S according to the received X' and the private key b of the second device, determines KA based on S, and decrypts CA according to KA to obtain (IA, A, CERTA, X, DataA); and if a public key certificate CERTA is valid and X' = AX d is effective, DataA is accepted. In the signcryption method provided by the invention, the identity and the public key information of the first device are hidden, the first device only needs to operate 2.5 modular exponentiations, and the second device only needs to operate 1.5 modular exponentiations. In addition, the bandwidth consumed by the method provided by the invention is less than an existing signcryption scheme, and the leakage of a temporary DH-index x does not affect the security of the scheme of the invention.

Description

technical field [0001] The invention relates to the technical field of encryption, in particular to an identity-hiding and strongly secure signcryption method. Background technique [0002] Digital signature and public key encryption are the core content of cryptographic theory and application. Signcryption combines the functions of digital signature and public key encryption into one, and the efficiency of separate signature and encryption is greatly improved. However, all existing signcryption schemes need to publicly transmit the user's identity and public key information. In the era of mobile Internet, user identities and public key certificate information are often sensitive information in many applications, so the development of identity-hiding signcryption methods has important theoretical and practical significance. [0003] The current mainstream and ISO-standardized signcryption scheme is the signcryption scheme given by Yuliang Zheng. Suppose the public key and...

AI Technical Summary

Problems solved by technology

However, the security of this modified signcryption scheme needs to be re-analyzed, and the efficiency is poor: the first user needs to run at least 2 modular exponential operations, and the second user needs to run 3 modular exponential operations

In addition, Zheng's signcryption scheme requires an additional transmission of (r, s), thus occupying additional bandwidth

Also, the leakage of the temporary DH-exponent x of Zheng’s signcryption scheme will completely break the security

Images