Re: unify entropy source for all php related functions

On Fri, Feb 14, 2014 at 1:02 PM, Andrey Andreev <narf@devilix.net> wrote: > On Fri, Feb 14, 2014 at 2:26 PM, Pierre Joye <pierre.php@gmail.com> wrote: > > > > On Feb 14, 2014 7:03 PM, "Andrey Andreev" <narf@devilix.net> wrote: > >> ALL sources > >> say that /dev/urandom is both widely used and considered safe for > >> cryptography. Only a select few mention that it could be a bit weaker > >> in specific cases, in theory. > > > > No urandom (and similar) are not crypto safe. Totally not. They are > however > > good enough for most usages but crypto safe related tasks like key > > generation and the likes. Any (good) paper mentions this. > > > > Cheers, > > Pierre > > So how does openssl_random_pseudo_bytes() work without blocking then? > > $ cat test.php > <?php > $crypto_strong = NULL; > $orandom = openssl_random_pseudo_bytes(32, $crypto_strong); > var_dump(bin2hex($orandom), $crypto_strong); > $mrandom = mcrypt_create_iv(32, MCRYPT_DEV_RANDOM); > var_dump($mrandom); > > $ php test.php > string(64) > "bc10fe2a302039bc0b1ff85b1da53d1b2dc73be515bc1ab9a4a1f8895da7357b" > bool(true) > (blocks) > > If it doesn't block, it obviously doesn't use (only) /dev/random, yet > it says that the output is crypto-safe. Or is that a bug? > OpenSSL uses their PRNG where /dev/urandom is used as a default source on Unix for seeding. See https://github.com/openssl/openssl/blob/master/e_os.h#L82 https://github.com/openssl/openssl/blob/master/crypto/rand/rand_unix.c#L246 and https://github.com/openssl/openssl/blob/master/crypto/rand/md_rand.c for PRNG implementation I think that they are considering the source strong enough for seeding but you can still add entropy if you want to. I have covered the complete OpenSSL API in my crypto ext. See the readme in https://github.com/bukka/php-crypto for more details (scroll down to see the the API for Crypto\Rand class) Regards Jakub