Everything about Seed totally explained
SEED is a
block cipher developed by the
Korean Information Security Agency. It is used broadly throughout
South Korean industry, but seldom found elsewhere. It gained popularity in Korea because 40 bit SSL wasn't considered strong enough (see
Transport Layer Security#Early short keys), so the Korean Information Security Agency developed its own standard. However, this decision has limited the competition of
web browsers in Korea, as no major SSL libraries or web browsers currently support the SEED algorithm, and users are limited to using
ActiveX components with
Internet Explorer for secure web sites.
SEED is a 16-round
Feistel network with
128-bit blocks and a
128-bit key. It uses two 8 × 8
S-boxes which, like those of
SAFER, are derived from discrete
exponentiation (in this case, x
247 and x
251 – plus some "incompatible operations"). It also has some resemblance to
MISTY1 in the recursiveness of its structure: the 128-bit full cipher is a Feistel network with an F-function operating on 64-bit halves, while the F-function itself is a Feistel network composed of a G-function operating on 32-bit halves. However the recursion doesn't extend further because the G-function isn't a Feistel network. In the G-function, the 32-bit word is considered as four 8-bit bytes, each of which is passed through one or the other of the S-boxes, then combined in a moderately complex set of
boolean functions such that each output bit depends on 3 of the 4 input bytes.
SEED has a fairly complex
key schedule, generating its thirty-two 32-bit subkeys through application of its G-function on a series of rotations of the raw key, combined with round constants derived (as in
TEA) from the
Golden ratio.
Further Information
Get more info on 'Seed'.
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