We announce the fourth prize for the most interesting cryptanalysis of Keccak. The results must be publicly available on an URL that is sent to keccak -at- noekeon -dot- org before June 30, 2010 at 12:00 GMT+2.

The fourth prize consists of chocolate and more exactly of pralines from one of the finest Belgian chocolate craftsmen. The first Belgian praline has been made in 1912 by Jean Neuhaus, and since then the praline has become one of the most renowned quality products from Belgium. The prize consists of a box of 600g (the number of rounds times the number of lanes in Keccak) of the finest Belgian pralines.

Like for the previous prizes, who wins will be decided by consensus in the Keccak team, based internally on a system of points. Some hints:

• Innovative ideas get more points than incremental results or applying standard techniques;
• For attacks with innovations that are comparable, the earlier ones get more points;
• Cryptanalysis or attack techniques applicable to a wider range of valid parameters r, c get more points (see the specifications for the definition of valid parameters);
  • Larger Keccak-f width gets more points;
  • Larger capacity gets more points;
• Attacks on reduced-round versions are allowed but more rounds get more points;
• For the same number of rounds, a distinguisher or attack on the Keccak sponge function gets more points than a distinguisher on Keccak-f only.

We reserve the right to extend the deadline in the absence of interesting results or when we consider that the presented results are too small increments compared to known results.

We hope analyzing Keccak is a fun and interesting challenge, and we appreciate any submitted work!