Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/cryptography/hazmat/backends/openssl/hashes.py: 27%

1# This file is dual licensed under the terms of the Apache License, Version 

2# 2.0, and the BSD License. See the LICENSE file in the root of this repository 

3# for complete details. 

4 

5import typing 

6 

7from cryptography.exceptions import UnsupportedAlgorithm, _Reasons 

8from cryptography.hazmat.primitives import hashes 

9 

10 

11if typing.TYPE_CHECKING: 

12 from cryptography.hazmat.backends.openssl.backend import Backend 

13 

14 

15class _HashContext(hashes.HashContext): 

16 def __init__( 

17 self, backend: "Backend", algorithm: hashes.HashAlgorithm, ctx=None 

18 ) -> None: 

19 self._algorithm = algorithm 

20 

21 self._backend = backend 

22 

23 if ctx is None: 

24 ctx = self._backend._lib.EVP_MD_CTX_new() 

25 ctx = self._backend._ffi.gc( 

26 ctx, self._backend._lib.EVP_MD_CTX_free 

27 ) 

28 evp_md = self._backend._evp_md_from_algorithm(algorithm) 

29 if evp_md == self._backend._ffi.NULL: 

30 raise UnsupportedAlgorithm( 

31 "{} is not a supported hash on this backend.".format( 

32 algorithm.name 

33 ), 

34 _Reasons.UNSUPPORTED_HASH, 

35 ) 

36 res = self._backend._lib.EVP_DigestInit_ex( 

37 ctx, evp_md, self._backend._ffi.NULL 

38 ) 

39 self._backend.openssl_assert(res != 0) 

40 

41 self._ctx = ctx 

42 

43 @property 

44 def algorithm(self) -> hashes.HashAlgorithm: 

45 return self._algorithm 

46 

47 def copy(self) -> "_HashContext": 

48 copied_ctx = self._backend._lib.EVP_MD_CTX_new() 

49 copied_ctx = self._backend._ffi.gc( 

50 copied_ctx, self._backend._lib.EVP_MD_CTX_free 

51 ) 

52 res = self._backend._lib.EVP_MD_CTX_copy_ex(copied_ctx, self._ctx) 

53 self._backend.openssl_assert(res != 0) 

54 return _HashContext(self._backend, self.algorithm, ctx=copied_ctx) 

55 

56 def update(self, data: bytes) -> None: 

57 data_ptr = self._backend._ffi.from_buffer(data) 

58 res = self._backend._lib.EVP_DigestUpdate( 

59 self._ctx, data_ptr, len(data) 

60 ) 

61 self._backend.openssl_assert(res != 0) 

62 

63 def finalize(self) -> bytes: 

64 if isinstance(self.algorithm, hashes.ExtendableOutputFunction): 

65 # extendable output functions use a different finalize 

66 return self._finalize_xof() 

67 else: 

68 buf = self._backend._ffi.new( 

69 "unsigned char[]", self._backend._lib.EVP_MAX_MD_SIZE 

70 ) 

71 outlen = self._backend._ffi.new("unsigned int *") 

72 res = self._backend._lib.EVP_DigestFinal_ex(self._ctx, buf, outlen) 

73 self._backend.openssl_assert(res != 0) 

74 self._backend.openssl_assert( 

75 outlen[0] == self.algorithm.digest_size 

76 ) 

77 return self._backend._ffi.buffer(buf)[: outlen[0]] 

78 

79 def _finalize_xof(self) -> bytes: 

80 buf = self._backend._ffi.new( 

81 "unsigned char[]", self.algorithm.digest_size 

82 ) 

83 res = self._backend._lib.EVP_DigestFinalXOF( 

84 self._ctx, buf, self.algorithm.digest_size 

85 ) 

86 self._backend.openssl_assert(res != 0) 

87 return self._backend._ffi.buffer(buf)[: self.algorithm.digest_size]