[messaging] symmetric cyphers with independent key material
Ben Harris
mail at bharr.is
Tue Oct 20 15:55:51 PDT 2015
On 21 October 2015 at 04:59, Natanael <natanael.l at gmail.com> wrote:
> Den 20 okt 2015 19:01 skrev "Jeff Burdges" <burdges at gnunet.org>:
> > Formally, there should be a function KG(s) that returns a tuple
> > (k_1,..,k_n) and a function P(k,d) such that if d_i = P(k_i,d_{i-1})
> > then d_n=d_0 but there are no known relationships between strictly
> > fewer than n of the k_i.
> >
>
> Secret Sharing on the symmetric key? Do you need it to be integrated into
> the encryption algorithm itself? Your terminology is a bit unclear to me,
> what exactly are you trying to achieve?
>
I think the request is for a keyed permutation P(k,d), and list of n
independent keys. Such that applying all of the n keys returns the original
plaintext, but that all the intermediate results (keys k_0 .. k_x for x <
n) are confidential.
I feel things like this are easier served with encrypting with a random
fixed length key K, then doing this n keys thing on the K instead of the
whole plaintext.
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