Cruising the stacks and finding stuff

[Sandy Harris]

Jack Lloyd <lloyd at randombit.net> wrote:

>  Making a cipher that uses an N bit key but is only secure to 2^M
>  operations with M<N is, firstly, considered broken in many circles, as
>  well as being inefficient (why generate/transmit/store 512 bit keys
>  when it only provides the security of a ~300 bit (or whatever) key
>  used with a perfect algorithm aka ideal cipher - why not use the
>  better cipher and save the bits).

Saving bits may not matter, or may not be possible. For example,
if you are ealing with a hybrid system -- say, using RSA to transmit
the symmetric cipher key or Diffie-Hellamn to construct it -- then for
any symmetric cipher key size less than the public key size, your
overheads are the same.

-- 
Sandy Harris,
Nanjing, China

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