Key Separation in Twofish

J. Kelsey

Twofish Technical Report #7, April 7, 2000

ABSTRACT: In [Mur00], Murphy raises questions about key separation in Twofish. We discuss this property of the Twofish key schedule, and compare it with other block ciphers. While every block cipher has this property in some abstract sense, the specific structure of Twofish makes it an interesting property to consider. We explain why we don't believe this property leads to any interesting attacks on Twofish, and describe what such attacks will have to look like if they do exist.

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