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From:    Andreas Westfeld <andreas westfeld at htw-dresden de>
Date:    Wed, 4 Jan, 2023 17:56
To:      crypto-competitions at list cr yp to
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* PGP - S/MIME Signed

Dear Keccak Team,

the messages 00 00 00 00 00 00 and 8B collide over rounds 3 and 4.

The collision was obtained by looking sharply.
(For zero input state, only the round constant matters. There is a zero round constant for i_r = 3 and b = 200. The round constant for i_r = 4 is 0x8b, which can be reproduced by another message in one block.)

   counter += verifyCollisionChallenge(
       // Keccak[r=40, c=160, rounds=2]: collision challenge
       40, 160, 2,
       3, // fill in this line with the start round index (0=first)
       (const UINT8*)"\0\0\0\0\0\0", 48, // fill in this line
       (const UINT8*)"\x8B", 8 // and this line with a different input
    );

Best regards,

Andreas Westfeld (HTW Dresden, Faculty of Informatics/Mathematics, Germany)

* Andreas Westfeld <andreas.westfeld@htw-dresden.de>
* Issuer: Verein zur Foerderung eines Deutschen Forschungsnetzes e. V.