+"""
+access to symmetric ciphers from libcrypto
+
+"""
from ctypes import create_string_buffer,c_char_p,c_void_p,c_int,c_long,byref,POINTER
from ctypescrypto import libcrypto
from ctypescrypto.exception import LibCryptoError
#
+__all__ = ['CipherError','new','Cipher','CipherType']
+
class CipherError(LibCryptoError):
pass
"""
self.cipher = libcrypto.EVP_get_cipherbyname(cipher_name)
if self.cipher is None:
- raise CipherError, "Unknown cipher: %s" % cipher_name
+ raise CipherError("Unknown cipher: %s" % cipher_name)
def __del__(self):
pass
iv_ptr = c_char_p(iv)
self.ctx = libcrypto.EVP_CIPHER_CTX_new()
if self.ctx == 0:
- raise CipherError, "Unable to create cipher context"
+ raise CipherError("Unable to create cipher context")
self.encrypt = encrypt
- if encrypt:
- enc = 1
- else:
- enc = 0
+ enc=1 if encrypt else 0
if not iv is None and len(iv) != cipher_type.iv_length():
raise ValueError("Invalid IV length for this algorithm")
result = libcrypto.EVP_CipherInit_ex(self.ctx, cipher_type.cipher, None, key_ptr, iv_ptr, c_int(enc))
if result == 0:
self._clean_ctx()
- raise CipherError, "Unable to initialize cipher"
+ raise CipherError("Unable to initialize cipher")
self.cipher_type = cipher_type
self.block_size = self.cipher_type.block_size()
self.cipher_finalized = False
"""
Sets padding mode of the cipher
"""
- if padding:
- padding_flag = 1
- else:
- padding_flag = 0
+ padding_flag=1 if padding else 0
libcrypto.EVP_CIPHER_CTX_set_padding(self.ctx, padding_flag)
def update(self, data):
called
"""
if self.cipher_finalized :
- raise CipherError, "No updates allowed"
- if type(data) != type(""):
- raise TypeError, "A string is expected"
- if len(data) <= 0:
+ raise CipherError("No updates allowed")
+ if not isinstance(data,str):
+ raise TypeError("A string is expected")
+ if len(data) == 0:
return ""
outbuf=create_string_buffer(self.block_size+len(data))
outlen=c_int(0)
state, they would be processed and returned.
"""
if self.cipher_finalized :
- raise CipherError, "Cipher operation is already completed"
+ raise CipherError("Cipher operation is already completed")
outbuf=create_string_buffer(self.block_size)
self.cipher_finalized = True
outlen=c_int(0)
result = libcrypto.EVP_CipherFinal_ex(self.ctx,outbuf , byref(outlen))
if result == 0:
self._clean_ctx()
- raise CipherError, "Unable to finalize cipher"
+ raise CipherError("Unable to finalize cipher")
if outlen.value>0:
return outbuf.raw[:outlen.value]
else: