This thesis provides several new combined differential, linear and related-key attacks, and shows their applications to block ciphers, hash functions in encryption mode and message authentication code (MAC) algorithms. The first part of this thesis introduces how to combine the differential-style, linear-style and related-key attacks: we combine them to devise the differential-nonlinear attack, the square-(non)linear attack, the related-key differential-(non)linear attack, the related-key boomerang attack and the related-key rectangle attack. The second part of this thesis presents some applications of the combined attacks to exiting symmetric-key cryptography. Firstly, we present their applications to the block ciphers SHACAL-1, SHACAL-2 and AES. In particular, we show that the differential-nonlinear attack is applicable to 32-round SHACAL-2, which leads to the best known attack on SHACAL-2 that uses a single key. We also show that the related-key rectangle attack is applicable to the full SHACAL-1, 42-round SHACAL-2 and 10-round AES-192, which lead to the first known attack on the full SHACAL-1 and the best known attacks on SHACAL-2 and AES-192 that use related keys. Secondly, we exploit the related-key boomerang attack to present practical distinguishing attacks on the cryptographic hash functions MD4, MD5 and HAVAL in encryption mode. Thirdly, we show that the related-key rectangle attack can be used to distinguish instantiated HMAC and NMAC from HMAC and NMAC with a random function.
Category / Keywords: secret-key cryptography / Combined Attacks, AES, SHACAL, MD4, MD5, HMAC Date: received 28 Nov 2006 Contact author: Kim Jongsung at esat kuleuven be Available formats: PDF | BibTeX Citation Note: The submission is Jongsung Kim's Ph.D. thesis approved by ESAT/COSIC in K.U.Leuven. Version: 20061204:102819 (All versions of this report) Discussion forum: Show discussion | Start new discussion