Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.11/site-packages/pypdf/_crypt_providers/_cryptography.py: 3%

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27 

28import secrets 

29 

30from cryptography import __version__ 

31from cryptography.hazmat.primitives.ciphers.algorithms import AES 

32from cryptography.hazmat.primitives.ciphers.base import Cipher 

33from cryptography.hazmat.primitives.ciphers.modes import CBC, ECB 

34from cryptography.hazmat.primitives.padding import PKCS7 

35 

36from pypdf._crypt_providers._base import CryptBase 

37from pypdf._utils import logger_warning 

38from pypdf.errors import PdfStreamError 

39 

40try: 

41 # 43.0.0: https://cryptography.io/en/latest/changelog/#v43-0-0 

42 from cryptography.hazmat.decrepit.ciphers.algorithms import ARC4 

43except ImportError: 

44 from cryptography.hazmat.primitives.ciphers.algorithms import ARC4 

45 

46crypt_provider = ("cryptography", __version__) 

47 

48 

49class CryptRC4(CryptBase): 

50 def __init__(self, key: bytes) -> None: 

51 self.cipher = Cipher(ARC4(key), mode=None) 

52 

53 def encrypt(self, data: bytes) -> bytes: 

54 encryptor = self.cipher.encryptor() 

55 return encryptor.update(data) + encryptor.finalize() 

56 

57 def decrypt(self, data: bytes, *, strict: bool = True) -> bytes: 

58 decryptor = self.cipher.decryptor() 

59 return decryptor.update(data) + decryptor.finalize() 

60 

61 

62class CryptAES(CryptBase): 

63 def __init__(self, key: bytes) -> None: 

64 self.alg = AES(key) 

65 

66 def encrypt(self, data: bytes) -> bytes: 

67 iv = secrets.token_bytes(16) 

68 padder = PKCS7(128).padder() 

69 padded_data = padder.update(data) + padder.finalize() 

70 

71 cipher = Cipher(self.alg, CBC(iv)) 

72 encryptor = cipher.encryptor() 

73 return iv + encryptor.update(padded_data) + encryptor.finalize() 

74 

75 def decrypt(self, data: bytes, *, strict: bool = True) -> bytes: 

76 iv = data[:16] 

77 data = data[16:] 

78 # for empty encrypted data 

79 if not data: 

80 return data 

81 

82 if not strict and len(data) % 16 != 0: 

83 logger_warning("Adding missing padding.", source=__name__) 

84 padder = PKCS7(128).padder() 

85 data = padder.update(data) + padder.finalize() 

86 

87 cipher = Cipher(self.alg, CBC(iv)) 

88 decryptor = cipher.decryptor() 

89 try: 

90 padded_data = decryptor.update(data) + decryptor.finalize() 

91 except ValueError as exception: 

92 # Only raised in strict mode. Non-strict mode fixes padding. 

93 raise PdfStreamError(exception) 

94 

95 unpadder = PKCS7(128).unpadder() 

96 try: 

97 return unpadder.update(padded_data) + unpadder.finalize() 

98 except ValueError as exception: 

99 if strict: 

100 raise PdfStreamError(exception) 

101 logger_warning("Ignoring padding error: %(exception)s", source=__name__, exception=exception) 

102 return padded_data[: -padded_data[-1]] 

103 

104 

105def rc4_encrypt(key: bytes, data: bytes) -> bytes: 

106 encryptor = Cipher(ARC4(key), mode=None).encryptor() 

107 return encryptor.update(data) + encryptor.finalize() 

108 

109 

110def rc4_decrypt(key: bytes, data: bytes) -> bytes: 

111 decryptor = Cipher(ARC4(key), mode=None).decryptor() 

112 return decryptor.update(data) + decryptor.finalize() 

113 

114 

115def aes_ecb_encrypt(key: bytes, data: bytes) -> bytes: 

116 encryptor = Cipher(AES(key), mode=ECB()).encryptor() 

117 return encryptor.update(data) + encryptor.finalize() 

118 

119 

120def aes_ecb_decrypt(key: bytes, data: bytes) -> bytes: 

121 decryptor = Cipher(AES(key), mode=ECB()).decryptor() 

122 return decryptor.update(data) + decryptor.finalize() 

123 

124 

125def aes_cbc_encrypt(key: bytes, iv: bytes, data: bytes) -> bytes: 

126 encryptor = Cipher(AES(key), mode=CBC(iv)).encryptor() 

127 return encryptor.update(data) + encryptor.finalize() 

128 

129 

130def aes_cbc_decrypt(key: bytes, iv: bytes, data: bytes) -> bytes: 

131 decryptor = Cipher(AES(key), mode=CBC(iv)).decryptor() 

132 return decryptor.update(data) + decryptor.finalize()