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Apr
13
answered Blind signature with openssl
Apr
7
awarded  Critic
Mar
30
comment What challenge should I use in a challenge-response proof-of-work?
Good point about multiple connections. You are right, in DoS prevention, I guess parallalization doesn't matter much. Yeah, scrypt is a nice way to meter based on processing power and memory accesses.
Mar
30
answered What challenge should I use in a challenge-response proof-of-work?
Mar
27
comment ZKIP for Paillier public key correctness
Yes, the proof is very complicated. I would consider using the exponential version of Elgamal ($\mathsf{Enc}(g^m)$ instead of $\mathsf{Enc}(m)$, see tinyurl.com/CGS1997) instead of Paillier if possible.
Mar
26
answered ZKIP for Paillier public key correctness
Mar
26
revised Division in paillier cryptosystem
edited tags
Mar
20
answered Order Preserving Encryption for Numeric Data Values
Mar
13
comment Division in paillier cryptosystem
@user996522 It depends on how you define "makes sense." If $a/b = c$, then $c \cdot b=a$. It is the same thing here. If you compute $a/b$ under encryption, you will get the encryption of the value $c$ such that $c \cdot b \bmod{n} = a$. You can think of it as "discrete division" akin to a discrete logarithm.
Mar
13
revised Division in paillier cryptosystem
added 78 characters in body
Mar
13
revised Division in paillier cryptosystem
added 797 characters in body
Mar
13
answered Division in paillier cryptosystem
Mar
9
comment Why do we use encrypt-decrypt-encrypt (EDE) in 3DES, rather than encrypting three times?
Duplicate on Security SE: security.stackexchange.com/questions/1886/…
Mar
8
answered Does security under ROM imply exactly what?
Mar
8
comment RSA-OAEP versus RSA with Fujisaki-Okamoto construction
In terms of your RSA construction, it is hard to say without trying to find a reduction. These things are very tricky. It does have a larger ciphertext than RSA-OAEP which is a drawback. (Also, "easier" isn't typically a design parameter. Unless if you mean more efficient or a more direct reduction to a known intractable problem. But easier to implement, to understand, etc., get trumped by efficiency.).
Mar
8
comment RSA-OAEP versus RSA with Fujisaki-Okamoto construction
(That was in reply to your previous comment).
Mar
8
comment RSA-OAEP versus RSA with Fujisaki-Okamoto construction
There seem be a hundred CCA-secure variants of Elgamal. It generally comes down to efficiency, ciphertext size, and your appetite for non-standard assumptions (random oracles, weird DH variants, etc). There is a good relatively recent paper that proposes a Elgamal variant (based on a new "twin DH" assumption) that does a nice job comparing to Elgamal, hashed Elgamal, FO Elgamal & Cramer-Shoup: iacr.org/archive/eurocrypt2008/49650126/49650126.pdf That is just scratching the surface: there is Naor-Young and a bunch of key encapsulation mechanisms (KEM)
Mar
7
answered RSA-OAEP versus RSA with Fujisaki-Okamoto construction
Feb
22
revised Threshold Signatures for RSA and DSA
added 220 characters in body
Feb
15
revised Is there some way to generate a non-predictable random number in a decentralised network?
added 17 characters in body