Method, device and system for processing cipher text

Abstract

The embodiment of the invention discloses a method, a device and a system for processing cipher text. The method comprises the following steps: selecting the random secret value by a cipher text transmitting terminal; calculating the key of the terminal according to the partial keys obtained by the terminal and the random secret value; calculating the proxy key according to the keys of the terminal and public keys published by a cipher text receiving terminal, wherein the public keys published by the cipher text receiving terminal are obtained through calculating by the cipher text receiving terminal according to the selected random secret value and public parameters of the system; and transmitting the proxy key so that the cipher text receiving terminal obtains the cipher text after being switched according to the cipher text transmitted to the cipher text transmitting terminal by the proxy key, and decrypts. After adopting the embodiment of the invention, the shortcoming of the cipher text re-encryption technology on collusion can be effectively prevented, and the safety of the information can be ensured. Simultaneously because of the realization of the invention, public key infrastructures (PKI) can be saved, and extensibility is better.

Description

technical field [0001] The present invention relates to the field of communications, in particular to a method, device and system for processing ciphertext. Background technique [0002] The ciphertext re-encryption technology is a technology that transforms the ciphertext without revealing the ciphertext information, and converts the received ciphertext into a ciphertext encrypted by the public key of the ciphertext receiving end. [0003] Specifically, suppose there are two users A and B, where the public key of user A is pk A , the private key is sk A ; User B's public key is pk B , the private key is sk B . Using the public / private key information of users A and B, a proxy key rk can be calculated AB . If user C holds proxy key rk AB , then user C can use pk A Encrypted messages are converted to use pk B An encrypted message, during the conversion process, User C cannot see the plaintext of the message. After the conversion is completed, user B can use his own ...

AI Technical Summary

Problems solved by technology

[0004] The existing ciphertext re-encryption technology has defects in collusion, that is, if user B and user C collude, they can calculate part of the private key information of user A, so that the encrypted message of user A is no longer safe

[0005] At the same time, the existing ciphertext re-encryption technology relies on the public key infrastructure (PKI), and the scalability of the public key infrastructure is poor, and it cannot support a large-scale user group.

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