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random.SystemRandom

Random class

A cryptographically secure generator that draws on os.urandom().

Syntax

random.SystemRandom()

Reproducibility is impossible by design: seed() does nothing and getstate()/setstate() raise NotImplementedError, so you cannot pin results for a test — use the ordinary random for that. When the goal is a password, token or key, reach for the secrets module instead: same entropy source, but with ready-made token_hex(), token_urlsafe() and compare_digest().

Examples

import random
srng = random.SystemRandom()
print(srng.random())  # → криптобезопасное [0,1)
print(srng.randint(1, 100))  # → безопасное целое
print(srng.choice(['a','b','c']))  # → безопасный выбор
srng.seed(42)  # seed у SystemRandom молча игнорируется: воспроизводимости нет
try:
    srng.getstate()
except NotImplementedError:
    print('getstate not supported')  # → getstate not supported
import os
print(len(os.urandom(16)))  # → 16

See also

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