On the Time - Memory Tradeo Between ExhaustiveKey

In cryptanalysis of block ciphers, there are several attacks that are always feasible and for which the success probability and complexity only depend on key length and/or block size. Exhaustive key search and table precomputation are two of such attacks. In Hel80] an attack was introduced which provides a tradeoo between the processing complexity of exhaustive key search and the memory complexity of table precomputation. We introduce a variant on the Hellman time-memory tradeoo, which decreases the expected number of memory accesses by a large factor and we demonstrate its advantages in a distributed key search.