Cryptology ePrint Archive: Report 2010/162

1024XKS - A High Security Software Oriented Block Cipher Revisited

Dieter Schmidt

Abstract: The block cipher 1024 has a key schedule that somehow resembles that of IDEA. The user key is cyclicly shifted by a fiexed amount to form the round keys. In the key schedule of IDEA this has lead to weak keys. The primitive key schedule from 1024 may lead also to attacks with related keys. Although to the knowlegde of the author weak keys or attacks with related keys have not yet been published, there is a need to put things right. The new one-way key schedule of 1024XKS (eXtended Key Schedule) has pseudo-random round keys, which are obtained by using the cipher as randomizer.Apart from that, the user key has now to sizes, 2048 bit and 4096 bit. Also the order of the s-boxes have been changed to thwart attacks based on symmetry

Category / Keywords: secret-key cryptography / high security encryption, block cipher, related key, weak key

Date: received 27 Mar 2010

Contact author: dieterschmidt at usa com

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Version: 20100328:180802 (All versions of this report)

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