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| -rw-r--r-- | ChangeLog | 52 |
1 files changed, 52 insertions, 0 deletions
@@ -1,3 +1,55 @@ +2.6.1 +===== + * [CVE-2013-1445] Fix PRNG not correctly reseeded in some situations. + + In previous versions of PyCrypto, the Crypto.Random PRNG exhibits a + race condition that may cause forked processes to generate identical + sequences of 'random' numbers. + + This is a fairly obscure bug that will (hopefully) not affect many + applications, but the failure scenario is pretty bad. Here is some + sample code that illustrates the problem: + + from binascii import hexlify + import multiprocessing, pprint, time + import Crypto.Random + + def task_main(arg): + a = Crypto.Random.get_random_bytes(8) + time.sleep(0.1) + b = Crypto.Random.get_random_bytes(8) + rdy, ack = arg + rdy.set() + ack.wait() + return "%s,%s" % (hexlify(a).decode(), + hexlify(b).decode()) + + n_procs = 4 + manager = multiprocessing.Manager() + rdys = [manager.Event() for i in range(n_procs)] + acks = [manager.Event() for i in range(n_procs)] + Crypto.Random.get_random_bytes(1) + pool = multiprocessing.Pool(processes=n_procs, + initializer=Crypto.Random.atfork) + res_async = pool.map_async(task_main, zip(rdys, acks)) + pool.close() + [rdy.wait() for rdy in rdys] + [ack.set() for ack in acks] + res = res_async.get() + pprint.pprint(sorted(res)) + pool.join() + + The output should be random, but it looked like this: + + ['c607803ae01aa8c0,2e4de6457a304b34', + 'c607803ae01aa8c0,af80d08942b4c987', + 'c607803ae01aa8c0,b0e4c0853de927c4', + 'c607803ae01aa8c0,f0362585b3fceba4'] + + This release fixes the problem by resetting the rate-limiter when + Crypto.Random.atfork() is invoked. It also adds some tests and a + few related comments. + 2.6 === * [CVE-2012-2417] Fix LP#985164: insecure ElGamal key generation. |