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Oct
12
revised Is there a public key semantically secure cryptosystem for which one can prove in zero knowledge the equivalence of two plaintexts?
added 232 characters in body
Oct
12
accepted Is there a public key semantically secure cryptosystem for which one can prove in zero knowledge the equivalence of two plaintexts?
Oct
11
revised Is there a public key semantically secure cryptosystem for which one can prove in zero knowledge the equivalence of two plaintexts?
deleted 2 characters in body
Oct
11
comment Is there a public key semantically secure cryptosystem for which one can prove in zero knowledge the equivalence of two plaintexts?
It does not need to be perfect zero knowledge. I suppose semantic security is enough. A computational zero knowledge argument will do fine.
Oct
11
asked Is there a public key semantically secure cryptosystem for which one can prove in zero knowledge the equivalence of two plaintexts?
Oct
10
revised What is the theoretical and practical status of mental poker?
added 152 characters in body
Oct
9
revised What is the theoretical and practical status of mental poker?
added 47 characters in body
Oct
9
answered What is the theoretical and practical status of mental poker?
Sep
12
accepted Is there a method to break an EC curve for all key-pairs (Q,d) such that (Q=d*G) faster than breaking every single key-pair?
Sep
12
comment Is there a method to break an EC curve for all key-pairs (Q,d) such that (Q=d*G) faster than breaking every single key-pair?
Great answer.That leaves Big-Step/Little-Step out of the question. Does Pollard's rho algorithm offer any trade off? It there any way one can find a trapdoor (e.g. isomorphism with some other field) so that the DLOG problem becomes easier?
Sep
12
comment Is there a method to break an EC curve for all key-pairs (Q,d) such that (Q=d*G) faster than breaking every single key-pair?
I've read baby-step giant-step algorithm for solving the discrete log and it uses a pre-computed table that can be reused to break following keys, but I don't know how the cost of building the table relates to the total cost of the algorithm. If building the table is 99% of the required time, then one can break 100 keys at the price of one. I don't see how Pollard's rho algorithm for logarithms can be optimized to break many key-pairs at the price of one.
Sep
12
comment Is there a method to break an EC curve for all key-pairs (Q,d) such that (Q=d*G) faster than breaking every single key-pair?
Suppose that, in a 160-bit curve, you could use 2^90 time/space to find a trapdoor so, afterwards, you can find any discrete log in O(1). Is that possible?
Sep
12
asked Is there a method to break an EC curve for all key-pairs (Q,d) such that (Q=d*G) faster than breaking every single key-pair?
Feb
2
accepted What type of hash functions provides non-malleability of hash digests?
Feb
2
asked What type of hash functions provides non-malleability of hash digests?
Nov
2
awarded  Teacher
Aug
30
accepted What is the signature scheme with the fastest batch verification protocol for multiple signers?
Aug
30
accepted Is there a cumulative commitment scheme?
Aug
30
comment What is the signature scheme with the fastest batch verification protocol for multiple signers?
Excellent review! But if you need to verify, say, 10000 signatures, then batching can really impact performance. I'm trying to figure out a scheme where verification of a batch of n signatures is O(1) or O(log n) "slow" operations (e.g. modexp) and O(n) "fast" operations (e.g. multiplication). Sadly I think such as scheme does not exists.
Aug
30
asked What is the signature scheme with the fastest batch verification protocol for multiple signers?