In
cryptography, Zodiac is a
block cipher
In cryptography, a block cipher is a deterministic algorithm operating on fixed-length groups of bits, called ''blocks''. Block ciphers are specified cryptographic primitive, elementary components in the design of many cryptographic protocols and ...
designed in 2000 by Chang-Hyi Lee for the Korean firm SoftForum.
Zodiac uses a 16-round
Feistel network structure with
key whitening. The round function uses only
XOR
Exclusive or or exclusive disjunction is a logical operation that is true if and only if its arguments differ (one is true, the other is false).
It is symbolized by the prefix operator J and by the infix operators XOR ( or ), EOR, EXOR, , ...
s and
S-box lookups. There are two 8×8-bit S-boxes: one based on the discrete
exponentiation 45
''x'' as in
SAFER, the other using the
multiplicative inverse in the
finite field GF(2
8), as introduced by
SHARK.
Zodiac is theoretically vulnerable to
impossible differential cryptanalysis, which can recover a 128-bit key in 2
119 encryptions.
References
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Further reading
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Broken block ciphers
Feistel ciphers
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