diff options
| -rw-r--r-- | Lib/test/test_random.py | 24 | ||||
| -rw-r--r-- | Modules/_randommodule.c | 18 |
2 files changed, 26 insertions, 16 deletions
diff --git a/Lib/test/test_random.py b/Lib/test/test_random.py index efac36a..50d4e94 100644 --- a/Lib/test/test_random.py +++ b/Lib/test/test_random.py @@ -758,7 +758,7 @@ class MersenneTwister_TestBasicOps(TestBasicOps, unittest.TestCase): # Mersenne Twister randbytes() is deterministic # and does not depend on the endian and bitness. seed = 8675309 - expected = b'f\xf9\xa836\xd0\xa4\xf4\x82\x9f\x8f\x19\xf0eo\x02' + expected = b'3\xa8\xf9f\xf4\xa4\xd06\x19\x8f\x9f\x82\x02oe\xf0' self.gen.seed(seed) self.assertEqual(self.gen.randbytes(16), expected) @@ -773,19 +773,35 @@ class MersenneTwister_TestBasicOps(TestBasicOps, unittest.TestCase): self.assertEqual(b''.join([self.gen.randbytes(4) for _ in range(4)]), expected) - # Each randbytes(2) or randbytes(3) call consumes 4 bytes of entropy + # Each randbytes(1), randbytes(2) or randbytes(3) call consumes + # 4 bytes of entropy self.gen.seed(seed) - expected2 = b''.join(expected[i:i + 2] + expected1 = expected[3::4] + self.assertEqual(b''.join(self.gen.randbytes(1) for _ in range(4)), + expected1) + + self.gen.seed(seed) + expected2 = b''.join(expected[i + 2: i + 4] for i in range(0, len(expected), 4)) self.assertEqual(b''.join(self.gen.randbytes(2) for _ in range(4)), expected2) self.gen.seed(seed) - expected3 = b''.join(expected[i:i + 3] + expected3 = b''.join(expected[i + 1: i + 4] for i in range(0, len(expected), 4)) self.assertEqual(b''.join(self.gen.randbytes(3) for _ in range(4)), expected3) + def test_randbytes_getrandbits(self): + # There is a simple relation between randbytes() and getrandbits() + seed = 2849427419 + gen2 = random.Random() + self.gen.seed(seed) + gen2.seed(seed) + for n in range(9): + self.assertEqual(self.gen.randbytes(n), + gen2.getrandbits(n * 8).to_bytes(n, 'little')) + def gamma(z, sqrt2pi=(2.0*pi)**0.5): # Reflection to right half of complex plane diff --git a/Modules/_randommodule.c b/Modules/_randommodule.c index 64e44e3..0fc2d07 100644 --- a/Modules/_randommodule.c +++ b/Modules/_randommodule.c @@ -534,31 +534,25 @@ _random_Random_randbytes_impl(RandomObject *self, Py_ssize_t n) return NULL; } - if (n == 0) { - /* Don't consume any entropy */ - return PyBytes_FromStringAndSize(NULL, 0); - } - PyObject *bytes = PyBytes_FromStringAndSize(NULL, n); if (bytes == NULL) { return NULL; } uint8_t *ptr = (uint8_t *)PyBytes_AS_STRING(bytes); - do { + for (; n; ptr += 4, n -= 4) { uint32_t word = genrand_uint32(self); -#if PY_LITTLE_ENDIAN - /* Convert to big endian */ +#if PY_BIG_ENDIAN + /* Convert to little endian */ word = _Py_bswap32(word); #endif if (n < 4) { - memcpy(ptr, &word, n); + /* Drop least significant bits */ + memcpy(ptr, (uint8_t *)&word + (4 - n), n); break; } memcpy(ptr, &word, 4); - ptr += 4; - n -= 4; - } while (n); + } return bytes; } |