# Tag Info

## New answers tagged randomness

0

Cryptography might not be philosophy, but the concept of true randomness is somewhat within that purview. It might be useful to cross post this in a philosophy forum and get their perspective. PRNGs and TRNG blur together if the PRNG is good. Some believe that *nix's /dev/random is pretty good. Some have passed what science has decided are exacting tests ...

4

I ran the command under dtruss on OSX, with it pointing to a static file. Even then, it appears to use this as an additional source of randomness to /dev/urandom. It's distasteful and almost certainly pointless. But assuming it only mixes the data into an already cryptographically-secure source of randomness, it's not actively harmful. That said, I can only ...

4

xagawa's original answer is almost correct, except for the valid concern pointed out by Florian in the comments. (The updated answer looks good to me.) The answer to the question is "yes," except that the most 'lattice-y' proof works for the modified version of the Regev system defined in Applebaum-Cash-Peikert-Sahai CRYPTO'09. (A version of this was also ...

4

I give another simple proof using the leftover hash lemma. The proof goes as follows, where I'll abuse the notation and assume that q is prime. Game0 The adversary can see $$(A,b,c,u,v,w,s) = (A, As+e, At+f, rA, rb+x\lfloor q/2 \rceil, rc+y\lfloor q/2 \rceil, s).$$ Game1 The view is changed as (A,b,c,u,v,w,s) = (A, As+e, c, rA, rb+x\lfloor q/2 \rceil, ...

1

If the keys and messages are known, yes, you can distinguish which were used - because you can test them all. If not, then this is "sligtly harder" (= not really possible with big enough values). Anything of the further answer will assume that the attacker doesn't know the keys or the messages. The definition of HMAC looks like this: \$HMAC(K, m) = H(K ...

0

Security analysis of "Nix /dev/random" is discussed here "Security Analysis of Pseudo-Random Number Generators with Input: /dev/random is not Robust", by Yevgeniy Dodis, David Pointcheval, Sylvain Ruhault, Damien Vergnaud, and Daniel Wichs. http://eprint.iacr.org/2013/338.pdf With an interesting blog ...

2

Yes, the Pseudo Random Number Generator (PRNG) in OpenSSL is Cryptographically Secure, which means it passes statistical tests, but as @Maarten Bodewes suggests in his comment, why not go one step further and use that PRNG directly, rather than through OpenSSL? OpenSSL can use EGD (which stands for Entropy Gathering Daemon). It is a process that taps into ...

Top 50 recent answers are included