Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/secrets.py: 61%

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 

17import os 

18 

19from hmac import compare_digest 

20from random import SystemRandom 

21 

22_sysrand = SystemRandom() 

23 

24randbits = _sysrand.getrandbits 

25choice = _sysrand.choice 

26 

27def randbelow(exclusive_upper_bound): 

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

29 if exclusive_upper_bound <= 0: 

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

31 return _sysrand._randbelow(exclusive_upper_bound) 

32 

33DEFAULT_ENTROPY = 32 # number of bytes to return by default 

34 

35def token_bytes(nbytes=None): 

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

37 

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

39 default is used. 

40 

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

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

43 

44 """ 

45 if nbytes is None: 

46 nbytes = DEFAULT_ENTROPY 

47 return os.urandom(nbytes) 

48 

49def token_hex(nbytes=None): 

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

51 

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

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

54 default is used. 

55 

56 >>> token_hex(16) #doctest:+SKIP 

57 'f9bf78b9a18ce6d46a0cd2b0b86df9da' 

58 

59 """ 

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

61 

62def token_urlsafe(nbytes=None): 

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

64 

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

66 or not supplied, a reasonable default is used. 

67 

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

69 'Drmhze6EPcv0fN_81Bj-nA' 

70 

71 """ 

72 tok = token_bytes(nbytes) 

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