White-box cryptograph non-linear encoding protection method based on table lookup

Abstract

The invention discloses a white-box cryptograph non-linear encoding protection method based on table lookup. The white-box cryptograph non-linear encoding protection method comprises the steps of: dividing m variables of a cryptographic algorithm into n groups, wherein each group comprises 16 bits, and subjecting the groups to Q0<1>, Q1<1>, ... , Qn-1<1> nonlinear transformation in sequence; regarding output results as input of an internal obfuscation part of the cryptographic algorithm of an SP structure, taking an AES algorithm for an example, and carrying out T transformation and MixColumns transformation; subjecting obtained results to one-time m bit input and m bit output nonlinear W<1>transformation; and acquiring final results of this turn of iteration, and sending the final results to the subsequent turn of iteration step. According to the white-box cryptograph non-linear encoding protection method, internal and external codes are subjected to non-linear bijective conversion simultaneously, and required operation is small since the algebraic degree of a single S box is no more than 8 and cannot be increased by MixColumn components and external radiation obfuscation codes; in addition, a master cryptography key is not directly restored when facing external algebra interpolation attacks, but an equivalent decrypting Boolean system is constructed, thus the security of the white-box cryptograph non-linear encoding protection method is higher.

Description

technical field [0001] The invention relates to the field of information security, in particular to a table look-up-based non-linear coding protection method for white-box ciphers. Background technique [0002] In the design and implementation of traditional cryptographic algorithms and security protocols, it is generally assumed that the operating environment terminals of cryptographic algorithms are safe and credible, and the security of the entire system lies in the confidentiality of keys. However, with the continuous development of digital information technology, studies have found that cryptographic software usually runs in an unsafe environment, such as the presence of malicious viruses and dishonest users. In this environment, an attacker can easily capture key information by observing or executing cryptographic software. A new security challenge is: how to hide the key information directly in the implementation of the algorithm in an open software code environment,...

AI Technical Summary

Problems solved by technology

The basic design idea of ​​white-box cipher is: for a given cryptographic algorithm and key information, the mapping from plaintext to ciphertext is determined; The execution process is completed by the lookup table method, the key is hidden in the table, but the attacker cannot extract the key from the lookup table

However, there is a common problem in the current white-box cipher schemes, that is, using the input and output characteristics of the lookup table, after eliminating the nonlinear part of the inner round scrambling code, only the linear scrambling operation is left in the outer code, so in The amount of calculation required to be broken under the white box condition is small, and the security of the password still needs to be further improved

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