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  • 13 votes cast
Jan
15
comment Instantiating a random oracle
The only thing I can think of is that in the case of hash functions the adversary knows the output of a query beforehand, while in the RO model no one knows the output until the query is made. This way an adversary can pre-compute hashes and use correlations between them to break most security proofs. All RO proofs require that the adversary cannot do any pre-compution on the hashes without knowledge of the challenger (the system).
Jan
15
answered Defining Symmetric vs Asymmetric cryptosystems
Sep
19
comment Why DSA cannot be used for encryption?
@CodesInChaos If DSA cannot be used for encryption, I think we should sue NIST and not Diffie-Hellman. :)
Sep
18
comment Time Capsule cryptography?
Compared to the <tongue-in-cheek> answer above, a more practical way would be to use the Disclaimer-based cryptosystem of Rawat and Saxena. This is more secure too. ;-)
Sep
11
awarded  Popular Question
Aug
12
comment Can ECDSA signatures be safely made “deterministic”?
Exactly, my question was related to a single signature. Thanks for the answer. Any way we can enforce this requirement, i.e., verify if it was deterministically generated using the given hash? (we probably need a special hash). Does the question even make sense? :)
Aug
12
comment Can ECDSA signatures be safely made “deterministic”?
Is it possible to verify if a signature was deterministic or not?
Jul
12
awarded  Yearling
Jun
23
awarded  Caucus
Jun
13
revised Can we reduce Diffie-Hellman problem to “Discrete-log inversion” problem?
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Jun
13
comment Can we reduce Diffie-Hellman problem to “Discrete-log inversion” problem?
Thanks for the ref. Some related questions: Suppose $n$ is composite and hard to factor. Which of the problems in Ch 21 are reducible? (1) Can Inverse-DH be reduced to Fixed-Inverse-DH? (2) Can Fixed-Inverse-DH be reduced to Fixed-DH?
Jun
13
accepted Can we reduce Diffie-Hellman problem to “Discrete-log inversion” problem?
Jun
13
revised Can we reduce Diffie-Hellman problem to “Discrete-log inversion” problem?
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Jun
13
awarded  Curious
Jun
12
revised Can we reduce Diffie-Hellman problem to “Discrete-log inversion” problem?
added 279 characters in body
Jun
12
revised Definition of indistinguishable schemes
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Jun
12
answered Definition of indistinguishable schemes
Jun
12
revised Can we reduce Diffie-Hellman problem to “Discrete-log inversion” problem?
added 66 characters in body
Jun
12
revised Can we reduce Diffie-Hellman problem to “Discrete-log inversion” problem?
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Jun
12
comment Can we reduce Diffie-Hellman problem to “Discrete-log inversion” problem?
@SOJPM; $(O(g^x))^x = g\in G$ (not $\bmod{n}$). Edited question to make this clear.