Differential entropy analysis of the IDEA block cipher

• Autores: Alex Biryukov, Jorge Nakahara Jr., Hamdi Murat Yildirim
• Localización: Journal of computational and applied mathematics, ISSN 0377-0427, Vol. 259, Nº 2, 2014, págs. 561-570
• Idioma: inglés
• DOI: 10.1016/j.cam.2013.08.002
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• Resumen

  • This paper describes a new cryptanalytic technique that combines differential cryptanalysis with Shannon entropy. We call it differential entropy (DE). The objective is to exploit the non-uniform distribution of output differences from a given mapping as a distinguishing tool in cryptanalysis. Our preferred target is the IDEA block cipher, since we detected significantly low entropy at the output of its multiplication operation. We looked to further extend this entropy analysis to larger components and for a number of rounds. We present key-recovery attacks on up to 2.5-round IDEA in the single-key model and without weakkey assumptions.