Method for security estimation of SPN-based block cipher against related-key attacks

Abstract

Symmetric block ciphers are among the most widely used cryptographic primitives. In addition to providing privacy via encryption, block ciphers are used as basic components in the construction of hash functions, message authentication codes, pseudorandom number generator, as part of various cryptographic protocols and etc. One of the most popular block ciphers nowadays is AES (Advanced Encryption Standard), which is used as a standard of symmetric encryption in many countries of the world. Several years ago it was found a theoretical attack exploiting AES key-expansion algorithm, and complexity of this attack is significantly lower comparing to brute force search. This article presents the algorithm for estimation of encryption algorithm security against related-key attacks, and its application to the perspective block cipher, which is a candidate to the block encryption standard in Ukraine.