We discuss the special requirements imposed on the underlying
cipher of systems which encrypt each sector of a disk
partition independently, and demonstrate a certificational
weakness in some existing block ciphers including Bellare and
Rogaway's 1999 proposal, proposing a new quantitative measure
of avalanche. To address these needs, we present Mercy, a new
block cipher accepting large (4096-bit) blocks, which uses a
key-dependent state machine to build a bijective F function
for a Feistel cipher. Mercy achieves 9 cycles/byte on a
Pentium compatible processor.
Key words: disk sector, large block, state
machine, avalanche, Feistel cipher.
Mercy home page:
http://www.cluefactory.org.uk/paul/mercy/
