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seen Oct 15 at 10:59

Sep
26
asked Need an introduction to SPKI (or “SPKI for dummies”)
Aug
2
awarded  Beta
Jul
18
comment Reduction from signatures to encryption?
@Zooko, Paolo: yes, the last para does elude to "designated verifier signatures" (DVS), which might work. The only issue is that DVS require the knowledge of verifiers or share a secret with them.
Jul
18
comment Reduction from signatures to encryption?
It seems one of the motivation for DSA was to make it hard to use for encryption (as export restrictions on signature schemes are not so strict).
Jul
17
comment Reduction from signatures to encryption?
(1) Keeping the signing key public may enable computation of verification key directly (at least it cannot be proved that it would not). Let (G, S, V) be a signature scheme, with usual meanings, now consider the modified scheme (G', S', V') as: G' = G, S' = (S, V), V' = V. Then the above idea does not work. (2) Alice does not send the forgery to Bob . Rather she uses the forgery (forged signature) as a secret key and only sends the message on which the forged signature was created. Using this message, Bob could compute the same forged signature, which can now act as a symmetric encryption key.
Jul
17
comment Reduction from signatures to encryption?
It would be great if there is a proof of this.
Jul
17
comment Reduction from signatures to encryption?
@Paulo: hmm yes Designated verifier signatures are a different beast. They might work. Though the question was motivated from DSA.
Jul
17
comment Reduction from signatures to encryption?
This won't work. The public verification key is public, so I am talking specifically about signatures, not MACs. But thanks for the answer :)
Jul
16
revised Reduction from signatures to encryption?
added 29 characters in body
Jul
16
comment How can SSL secure a two-way communication with only one key-pair?
I am assuming you meant that the "third value that the eavesdropper cannot discern" is a nonce. At least thats what it seems from the text.
Jul
16
awarded  Student
Jul
16
asked Reduction from signatures to encryption?
Jul
16
awarded  Commentator
Jul
16
comment How can SSL secure a two-way communication with only one key-pair?
And of course, the client needs a certificate too, to support the client authentication.
Jul
16
comment How can SSL secure a two-way communication with only one key-pair?
Note: I think you refer to authentication via a certificate. You didn't mention it.
Jul
16
awarded  Supporter
Jul
16
awarded  Critic
Jul
16
comment How can SSL secure a two-way communication with only one key-pair?
nonces are used to avoid replay attacks, and not for "protecting" the secret value from eveasdroppers. And, TLS does not require the server to have an encryption key. A DSA key will also work. The two parties will use DH key exchange in this case.
Jul
16
revised Current mathematics theory used in cryptography/coding theory
added 1 characters in body
Jul
16
comment How can SSL secure a two-way communication with only one key-pair?
and don't believe everything that wikipedia says.