Coverage for /pythoncovmergedfiles/medio/medio/usr/lib/python3.9/secrets.py: 59%

1"""Generate cryptographically strong pseudo-random numbers suitable for 

2managing secrets such as account authentication, tokens, and similar. 

3 

4See PEP 506 for more information. 

5https://www.python.org/dev/peps/pep-0506/ 

6 

7""" 

8 

9__all__ = ['choice', 'randbelow', 'randbits', 'SystemRandom', 

10 'token_bytes', 'token_hex', 'token_urlsafe', 

11 'compare_digest', 

12 ] 

13 

14 

15import base64 

16import binascii 

17 

18from hmac import compare_digest 

19from random import SystemRandom 

20 

21_sysrand = SystemRandom() 

22 

23randbits = _sysrand.getrandbits 

24choice = _sysrand.choice 

25 

26def randbelow(exclusive_upper_bound): 

27 """Return a random int in the range [0, n).""" 

28 if exclusive_upper_bound <= 0: 

29 raise ValueError("Upper bound must be positive.") 

30 return _sysrand._randbelow(exclusive_upper_bound) 

31 

32DEFAULT_ENTROPY = 32 # number of bytes to return by default 

33 

34def token_bytes(nbytes=None): 

35 """Return a random byte string containing *nbytes* bytes. 

36 

37 If *nbytes* is ``None`` or not supplied, a reasonable 

38 default is used. 

39 

40 >>> token_bytes(16) #doctest:+SKIP 

41 b'\\xebr\\x17D*t\\xae\\xd4\\xe3S\\xb6\\xe2\\xebP1\\x8b' 

42 

43 """ 

44 if nbytes is None: 

45 nbytes = DEFAULT_ENTROPY 

46 return _sysrand.randbytes(nbytes) 

47 

48def token_hex(nbytes=None): 

49 """Return a random text string, in hexadecimal. 

50 

51 The string has *nbytes* random bytes, each byte converted to two 

52 hex digits. If *nbytes* is ``None`` or not supplied, a reasonable 

53 default is used. 

54 

55 >>> token_hex(16) #doctest:+SKIP 

56 'f9bf78b9a18ce6d46a0cd2b0b86df9da' 

57 

58 """ 

59 return binascii.hexlify(token_bytes(nbytes)).decode('ascii') 

60 

61def token_urlsafe(nbytes=None): 

62 """Return a random URL-safe text string, in Base64 encoding. 

63 

64 The string has *nbytes* random bytes. If *nbytes* is ``None`` 

65 or not supplied, a reasonable default is used. 

66 

67 >>> token_urlsafe(16) #doctest:+SKIP 

68 'Drmhze6EPcv0fN_81Bj-nA' 

69 

70 """ 

71 tok = token_bytes(nbytes) 

72 return base64.urlsafe_b64encode(tok).rstrip(b'=').decode('ascii')