Ciphertext generation method and device

Abstract

The invention discloses a ciphertext generation method, and the method comprises the steps: obtaining a first ciphertext which is a ciphertext obtained after the encryption of a target message throughan information digest algorithm; performing logical operation processing and / or shift processing on the first ciphertext to generate a second ciphertext; intercepting a part of ciphertext with a preset length from the second ciphertext, and inputting the part of ciphertext with the preset length into a random number generation function to obtain a randomly processed ciphertext with the preset length; and replacing a part of intercepted ciphertext with the preset length in the second ciphertext with the randomly processed ciphertext with the preset length, and obtaining a third ciphertext after replacement. According to the method, on the basis of remarkably improving the complexity of the ciphertext, the length of the ciphertext is kept unchanged, influence on a system interface and a message format encrypted by an existing MD5 algorithm is small, and the cost and difficulty of system transformation encrypted by the existing MD5 algorithm are reduced.

Description

technical field [0001] The present application relates to the field of communication technologies, and in particular to a method and device for generating ciphertext. Background technique [0002] Message-Digest Algorithm (MD5) is a cryptographic hash function that generates a 128-bit hash value, and is widely used in existing application systems. However, with the continuous development of computer computing power and the accumulation of collision cipher libraries during the application of the MD5 algorithm, the ciphertext generated by the MD5 algorithm may be cracked by violence. [0003] At present, the existing technology replaces the MD5 algorithm with the SHA-2 algorithm (Secure Hash Algorithm 2, Secure Hash Algorithm 2) that generates a 256-bit hash value to prevent the ciphertext generated by it from being violently cracked, but because the MD5 algorithm and SHA- 2 The length of the ciphertext generated by the algorithm is different. This improvement will have an im...

AI Technical Summary

Problems solved by technology

[0003] At present, the existing technology replaces the MD5 algorithm with the SHA-2 algorithm (Secure Hash Algorithm 2, Secure Hash Algorithm 2) that generates a 256-bit hash value to prevent the ciphertext generated by it from being violently cracked, but because the MD5 algorithm and SHA- 2 The length of the ciphertext generated by the algorithm is different. This improvement will have an impact on the interface and message format of the existing system, and the cost of transformation is high and difficult.

Images