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 Feb 18 answered How to show that a function is not a PRP? Feb 17 reviewed Approve What prime lengths are used for RSA? Feb 15 reviewed Approve Is there a security analysis of CryptDB? Feb 14 comment How much computing resource is required to brute-force RSA? @dave_thompson_085 "Slightly" by two orders of magnitude. :D Fixed it. (though it's 5.95495, so 5.95) Feb 14 revised How much computing resource is required to brute-force RSA? edited body Feb 9 comment Hash function as secure as one-time pad? This does not seem to attempt to answer the question. Feb 8 comment Is $f(x)\oplus x$ a one-way function? If one-way functions do not exist, then the statement is trivially true, because it is an all quantified statement about the empty set. Feb 8 comment Is $f(x)\oplus x$ a one-way function? Thanks, fixed the $x_1$ mixup. About the generality, yes that is true, as long as the length of $x_1$ is superlogarithmic, everything should be fine. But as this is a counter example, I think it's fine to be more specific. Feb 8 revised Is $f(x)\oplus x$ a one-way function? added 1 character in body Feb 8 answered Is $f(x)\oplus x$ a one-way function? Feb 2 answered Definition of ciphertext security Feb 2 comment Definition of ciphertext security Where does it state in the screenshot that such a scheme is secure? Feb 2 comment Definition of ciphertext security Where do you get the idea from that such a scheme would be CCA secure? Jan 29 answered Definition of the Decryption oracle Jan 22 comment Is it an example of bilinear pairing? The second one is not bilinear: $e(x,y^z) =x^{(y^z)} \neq (x^{yz})} = e(x,y)^z$. For the first one I don't see the problem with bilinearity at the moment, but the group is pretty useless for crypto since discrete log is trivial. Jan 12 reviewed Approve How much (home PC) CPU time is required to generate a prime number of a given size? Jan 12 awarded Enlightened Jan 12 awarded Nice Answer Jan 2 comment Why is proof-by-reduction needed (for Elgamal proof of security, for example)? @curious I'm only showing that the distribution is not uniform, not that it can be efficiently distinguished from a uniform distribution. Nov 16 comment plaintext distribution ,perfect secrecy cryptosystem I'm not sure that the claim actually holds. Are you sure that there are no additional constraints on the "specific plaintext distribution"? Unless I'm confused, any encryption scheme (or even the identityfunction) offers perfect secrecy for the distribution that has probability 0 for all but one plaintext. But obviously this does not imply perfect secrecy for other distributions.