Method, device and system for processing cipher text

Abstract

Embodiments of the present invention disclose a ciphertext processing method, apparatus, and system. The method includes: selecting, by a ciphertext sending end, a random secret value; calculating a private key of a local end according to a partial private key acquired by the local end and the random secret value; calculating a proxy key according to the private key of the local end and a public key publicized by a ciphertext receiving end, where the public key publicized by the ciphertext receiving end is calculated by the ciphertext receiving end according to a random secret value selected by the ciphertext receiving end and a system public parameter; and sending the proxy key, so that the ciphertext receiving end acquires a ciphertext obtained after a re-encryption operation is performed, according to the proxy key, on a ciphertext sent by the ciphertext sending end, and performs decryption. Existing defects of a ciphertext re-encrypting technology in a collusion aspect can be effectively avoided by adopting the embodiments of the present invention, thereby better ensuring information security, and meanwhile, implementation of the present invention avoids using a public key infrastructure (PKI), thereby having better extensibility.

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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