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Re: Internet Protocol Security Protocol (ipsec)
Bob,
There is a DES mode defined (OFB) for providing the
precomputation capability you describe. It uses the DES in a feedback
arrangement to generate a pseudo-random sequence from a random or
pesdue-random seed value, but it fails to provide unpredictable error
propogation, an important feature in support of detecting modification
(as does your scheme). I'd suggest you adopt that scheme if you want
a precomputation capability, but it would be less desirable for
general use in the IPSEC context because of this defficiency.
Steve
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