Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/werkzeug/security.py: 22%

1from __future__ import annotations 

2 

3import hashlib 

4import hmac 

5import os 

6import posixpath 

7import secrets 

8 

9SALT_CHARS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" 

10DEFAULT_PBKDF2_ITERATIONS = 600000 

11 

12_os_alt_seps: list[str] = list( 

13 sep for sep in [os.sep, os.path.altsep] if sep is not None and sep != "/" 

14) 

15 

16 

17def gen_salt(length: int) -> str: 

18 """Generate a random string of SALT_CHARS with specified ``length``.""" 

19 if length <= 0: 

20 raise ValueError("Salt length must be at least 1.") 

21 

22 return "".join(secrets.choice(SALT_CHARS) for _ in range(length)) 

23 

24 

25def _hash_internal(method: str, salt: str, password: str) -> tuple[str, str]: 

26 method, *args = method.split(":") 

27 salt_bytes = salt.encode() 

28 password_bytes = password.encode() 

29 

30 if method == "scrypt": 

31 if not args: 

32 n = 2**15 

33 r = 8 

34 p = 1 

35 else: 

36 try: 

37 n, r, p = map(int, args) 

38 except ValueError: 

39 raise ValueError("'scrypt' takes 3 arguments.") from None 

40 

41 maxmem = 132 * n * r * p # ideally 128, but some extra seems needed 

42 return ( 

43 hashlib.scrypt( 

44 password_bytes, salt=salt_bytes, n=n, r=r, p=p, maxmem=maxmem 

45 ).hex(), 

46 f"scrypt:{n}:{r}:{p}", 

47 ) 

48 elif method == "pbkdf2": 

49 len_args = len(args) 

50 

51 if len_args == 0: 

52 hash_name = "sha256" 

53 iterations = DEFAULT_PBKDF2_ITERATIONS 

54 elif len_args == 1: 

55 hash_name = args[0] 

56 iterations = DEFAULT_PBKDF2_ITERATIONS 

57 elif len_args == 2: 

58 hash_name = args[0] 

59 iterations = int(args[1]) 

60 else: 

61 raise ValueError("'pbkdf2' takes 2 arguments.") 

62 

63 return ( 

64 hashlib.pbkdf2_hmac( 

65 hash_name, password_bytes, salt_bytes, iterations 

66 ).hex(), 

67 f"pbkdf2:{hash_name}:{iterations}", 

68 ) 

69 else: 

70 raise ValueError(f"Invalid hash method '{method}'.") 

71 

72 

73def generate_password_hash( 

74 password: str, method: str = "scrypt", salt_length: int = 16 

75) -> str: 

76 """Securely hash a password for storage. A password can be compared to a stored hash 

77 using :func:`check_password_hash`. 

78 

79 The following methods are supported: 

80 

81 - ``scrypt``, the default. The parameters are ``n``, ``r``, and ``p``, the default 

82 is ``scrypt:32768:8:1``. See :func:`hashlib.scrypt`. 

83 - ``pbkdf2``, less secure. The parameters are ``hash_method`` and ``iterations``, 

84 the default is ``pbkdf2:sha256:600000``. See :func:`hashlib.pbkdf2_hmac`. 

85 

86 Default parameters may be updated to reflect current guidelines, and methods may be 

87 deprecated and removed if they are no longer considered secure. To migrate old 

88 hashes, you may generate a new hash when checking an old hash, or you may contact 

89 users with a link to reset their password. 

90 

91 :param password: The plaintext password. 

92 :param method: The key derivation function and parameters. 

93 :param salt_length: The number of characters to generate for the salt. 

94 

95 .. versionchanged:: 2.3 

96 Scrypt support was added. 

97 

98 .. versionchanged:: 2.3 

99 The default iterations for pbkdf2 was increased to 600,000. 

100 

101 .. versionchanged:: 2.3 

102 All plain hashes are deprecated and will not be supported in Werkzeug 3.0. 

103 """ 

104 salt = gen_salt(salt_length) 

105 h, actual_method = _hash_internal(method, salt, password) 

106 return f"{actual_method}${salt}${h}" 

107 

108 

109def check_password_hash(pwhash: str, password: str) -> bool: 

110 """Securely check that the given stored password hash, previously generated using 

111 :func:`generate_password_hash`, matches the given password. 

112 

113 Methods may be deprecated and removed if they are no longer considered secure. To 

114 migrate old hashes, you may generate a new hash when checking an old hash, or you 

115 may contact users with a link to reset their password. 

116 

117 :param pwhash: The hashed password. 

118 :param password: The plaintext password. 

119 

120 .. versionchanged:: 2.3 

121 All plain hashes are deprecated and will not be supported in Werkzeug 3.0. 

122 """ 

123 try: 

124 method, salt, hashval = pwhash.split("$", 2) 

125 except ValueError: 

126 return False 

127 

128 return hmac.compare_digest(_hash_internal(method, salt, password)[0], hashval) 

129 

130 

131def safe_join(directory: str, *pathnames: str) -> str | None: 

132 """Safely join zero or more untrusted path components to a base 

133 directory to avoid escaping the base directory. 

134 

135 :param directory: The trusted base directory. 

136 :param pathnames: The untrusted path components relative to the 

137 base directory. 

138 :return: A safe path, otherwise ``None``. 

139 """ 

140 if not directory: 

141 # Ensure we end up with ./path if directory="" is given, 

142 # otherwise the first untrusted part could become trusted. 

143 directory = "." 

144 

145 parts = [directory] 

146 

147 for filename in pathnames: 

148 if filename != "": 

149 filename = posixpath.normpath(filename) 

150 

151 if ( 

152 any(sep in filename for sep in _os_alt_seps) 

153 or os.path.isabs(filename) 

154 or filename == ".." 

155 or filename.startswith("../") 

156 ): 

157 return None 

158 

159 parts.append(filename) 

160 

161 return posixpath.join(*parts)