Cryptology ePrint Archive: Report 2020/983

A Differential Meet-in-the-Middle Attack on the Zip cipher

Michael Stay

Abstract: We report the successful recovery of the key to a Zip archive containing only two encrypted files. The attack improves on our 2001 ciphertext-only attack, which required five encrypted files. The main innovations are a new differential meet-in-the-middle attack for the initial stages and the use of lattice reduction to recover the internal state of the truncated linear congruential generator.

Category / Keywords: secret-key cryptography / Cryptanalysis, stream ciphers

Date: received 14 Aug 2020

Contact author: stay at pyrofex net

Available format(s): PDF | BibTeX Citation

Version: 20200818:083405 (All versions of this report)

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