code review 569044: crypto/rand: new package

crypto/rand: new package Until proven insufficient, rely on the operating system to give us good random bytes (/dev/urandom).

[rsc, 2010-03-16 22:35:42]

Hello agl1 (cc: golang-dev@googlegroups.com), I'd like you to review this change.

[agl1, 2010-03-16 22:52:35]

LGTM. A couple of notes. With the addition of the Nanoseconds call, this might be slower than /dev/urandom on 32-bit systems. (64-bit systems have VDSO, so it might be ok there.) Secondly, /dev/random blocks a lot and for an arbitrary amount of time. Either it should see itself from /dev/urandom or there should be blazing huge warnings to that effect in the comments.

[rsc, 2010-03-16 23:15:59]

> A couple of notes. With the addition of the Nanoseconds call, this might > be slower than /dev/urandom on 32-bit systems. (64-bit systems have > VDSO, so it might be ok there.) > > Secondly, /dev/random blocks a lot and for an arbitrary amount of time. > Either it should see itself from /dev/urandom or there should be blazing > huge warnings to that effect in the comments. Is /dev/urandom reliable enough? I'm happy to seed from or just read directly from there, but I was also trying to do something that had better worst case entropy than /dev/random. What do other libraries do for the random bytes they need for, say, key generation? Russ 

[agl1, 2010-03-17 01:17:34]

On Tue, Mar 16, 2010 at 7:15 PM, Russ Cox <rsc@golang.org> wrote: > Is /dev/urandom reliable enough?  I'm happy to seed from or just > read directly from there, but I was also trying to do something that > had better worst case entropy than /dev/random. /dev/urandom is pretty good. > What do other libraries do for the random bytes they need for, > say, key generation? GPG maintains a random seed file in your home dir. If the seed is exhausted it appears to use both /dev/random (to exhaustion) and /dev/urandom. OpenSSL just uses /dev/urandom. Non blocking is important enough that it should be an option, although there are cases where /dev/random is warranted (like key gen). AGL 

[rsc, 2010-03-17 01:58:50]

Hello agl1 (cc: golang-dev@googlegroups.com), Please take another look.

[agl1, 2010-03-17 02:20:09]

LGTM

[rsc, 2010-03-17 06:12:22]

*** Submitted as http://code.google.com/p/go/source/detail?r=c827563980e5 *** crypto/rand: new package Until proven insufficient, rely on the operating system to give us good random bytes (/dev/urandom). R=agl1 CC=golang-dev http://codereview.appspot.com/569044