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Re: Proposals for key-ed MD5
Hugo:
... One advantage of (II) over the plain MD5(K|text|K) is that more
than one iteration of MD5 takes place even in case text is very
short. Moreover there is an implementation option of pre-computing
MD5(K|1|0^383) and using the result as input to the ABCD registers
of MD5; in this way the computation due to the prepended key is
done only once per key.
I like this. The precomputation is attractive, and one MD5 operation can
be used to compute the integrity check value. In periperial hardware
implementations, like PCMCIA cards, it is better to have one command do the
whole thing. It simply avoids I/O through the relatively slow card
interface.
Russ