Research On Multi-receiver Identity-based Anonymous Signcryption

Signcryption technology combines the digital signature with public key encryption,and provides an approach to transmit messages with both confidentiality andauthenticity. Multi-receiver signcryption technology combines the multi-receiverencryption with signcryption. The signcrypter can send a same message to manyreceivers by only one signcryption operation, thus improving the traditional methodwhich has the shortcomings of large calculation, large communication and lowefficiency, so it has been viewed as an important technology which can realize multicastkey distribution and effectively solve the multicast key management issues. At present,multi-receiver signcryption technology has become a research hotspot in the areas ofcryptography and information security.However, it is found that the ciphertext information of most of the existingmulti-receiver signcryption schemes completely exposes the receivers’ identity, becausein this scheme, all the authorized users’ identity information and its correlation order areparts of the ciphertext. In addition to solve the privacy problem, the existing schemeswith this approach will also lead to decrypt unfairness, that is to say, when theciphertext is information partly damaged, a part of the authorized users can decryptcorrectly, but the other part cannot. This will lead to certain limitations in the actualapplication.Aiming at the the problem of receiver privacy exposure and decryption unfairnesswhich exists in the existing multi-receiver signcryption schemes, two newmulti-receiver signcryption schemes are proposed to achieve the anonymity of only thereceivers and the anonymity of both the signcrypter and the receivers. By usingLagrange interpolation function, the broadcast information of the scheme no longerdirectly includes the receivers’ identity list in the ciphertext, so it doesn’t display thereceivers’ identity intuitively, which not only make the attacker cannot get the receiver’sinformation but also let all the receivers who receive the same messages cannot receiveany other receiver’s information except themselves. Thus we solve the user’s privacyissues. At the same time, the different information needed by each receiver is changedinto a public information collection, which makes all authorized receivers have the samechance to decrypt the ciphtertext, so the proposed scheme satisfies the decryptionfairness.