Re: Efficient asymmetric encryption (Newbie)


Sorry if this seems obvious but to clarify,
If k1..kn are symetric keys, when the machine is compromised, all the
data
recorded whilst the current key was in use will be compromised. And if
H(.)
can be discovered (from the program code) maybe k(i-1),k(i-2),...,k(i-n)
can
also be disovered ?

No, if it's a oneway hash you shouldn't be able to compute k(i-1) from
k(i). That's the point. As he said though all future keys would be
compromised.

Thanks again everyone, for pointing me in the right direction, this sounds
like the way to go but I need to do some reading. A google of "cryptography
key evolution" yielded
http://www.cs.bu.edu/~itkis/pap/forward-secure-survey.pdf so I'm going to
get a little brain fry in today.
Bruce.


.

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