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Dec
20
comment Is this algorithm demonstrating “proof of work”
In the future, we generally ask that questions on Crypto.SE should use pseudocode to describe the algorithm concisely -- rather than giving a full implementation. Here the code makes it harder to understand what is going on, whereas you could describe the basic algorithm in one or two lines of simple mathematics. Just letting you know for the future....
Dec
20
comment Is this algorithm demonstrating “proof of work”
@kylek, I think you've misunderstood rolfl's answer. Rolfl is 100% correct on both of his criticisms, and I think you misunderstood his points and haven't fully grokked his critique yet. Maybe read it a second time? (Rolfl clearly does understand that this is for proof-of-work, not for authentication.)
Dec
20
answered Is this algorithm demonstrating “proof of work”
Dec
19
comment Are those two distributions indistinguishable?
Thanks, @curious, that was a typo on my part. I certainly intended it to be mod $N^2$, but that did not make it from my brain to my fingers -- oops. Fixed. Thank you again.
Dec
19
revised Are those two distributions indistinguishable?
added 2 characters in body
Dec
19
answered Are those two distributions indistinguishable?
Dec
19
comment Are those two distributions indistinguishable?
Are you sure you've got the definition of the decisional quadratic residuosity problem right? Do you have a reference? I'm not familiar with this specific hardness assumption, but based on the name, I would have expected something called the "decisional quadratic residuosity problem" to be about $x^2 \bmod N^2$ vs $r \bmod N^2$.
Dec
19
comment Is a Mersenne-twister cryptographically secure if I truncate the output?
Greg, the first step is to start by asking questions rather than drawing conclusions (such as the conclusion that Mersenne Twister is fine). You should be especially careful when your conclusions seem to run counter to what others have told you. Asking questions shows that you want to learn. Here's a starting tip: Mersenne Twister is insecure from a cryptographic perspective, and the fact that you only output partial output does not change that. You need cryptographic-level security, and the best way to get that is a CSPRNG -- which Mersenne Twister is not.
Dec
19
comment Is a Mersenne-twister cryptographically secure if I truncate the output?
Wow. There's a pretty impressive amount of misconception shown here. All I can say is: You are not qualified to write a casino game. Don't do it. There is specific technical knowledge required to do this right, and you do not have it. Try to find someone more qualified to do this aspect of design, because your instincts are leading you astray, your reasoning is wrong, your conclusion is wrong (and worse, you seem convinced that you are right).
Dec
17
answered Attacks against El Gamal private key
Dec
17
revised Help with linear cryptanalysis
Add Matsui paper.
Dec
17
comment Help with linear cryptanalysis
@Antimony - yup, that's certainly possible! The only thing I couldn't tell was: what is the best characteristic you've gotten? How many rounds, and with what bias (or what probability)? It's possible that if you asked a new question giving that specific characteristic and asking if anyone can do better, maybe someone would be inspired to try to find a better one and see if they can beat what you got. Anyway, great question -- sorry I wasn't able to give a more specific answer focused on this particular cipher.
Dec
16
revised Help with linear cryptanalysis
References.
Dec
16
revised Help with linear cryptanalysis
References.
Dec
16
revised Help with linear cryptanalysis
added 2357 characters in body
Dec
16
answered Help with linear cryptanalysis
Dec
16
comment Combining two hashing functions
possible duplicate of Guarding against cryptanalytic breakthroughs: combining multiple hash functions
Dec
16
comment Combining two hashing functions
Are you using cryptographic hash functions? If not, this is off-topic for Cryptography.SE.
Dec
15
comment Randomized stream cipher using multivariant quadratic equations
@Antimony, yeah, $n^2/2$ should suffice. I wasn't trying to optimize the constant factors (just laziness). Thank you.
Dec
12
awarded  Nice Answer