def decrypt_file(self, in_file_path, out_file_path, password = None):
with open(in_file_path, 'rb') as in_file:
#If a password is provided, generate key and iv using salt from file.
if password is not None:
self._salt = in_file.read(32)
self.create_key_from_password(password)
#Key and iv have not been generated or provided, bail out
if self._key is None or self._iv is None:
return False
#Initialize encryption using key and iv
key_expander_256 = KeyExpander(256)
expanded_key = key_expander_256.expand(self._key)
aes_cipher_256 = AESCipher(expanded_key)
aes_cbc_256 = CBCMode(aes_cipher_256, 16)
aes_cbc_256.set_iv(self._iv)
#Read original file size
filesize = struct.unpack('L',in_file.read(4))[0]
#Decrypt to eof
with open(out_file_path, 'wb') as out_file:
while 1:
in_data = bytearray(in_file.read(16))
if not in_data:
self._salt = None
return True
else:
out_data = aes_cbc_256.decrypt_block(bytearray(in_data))
#At end of file, if end of original file is within < 16 bytes slice it out.
out_file.write(self.fix_bytes(
out_data[:filesize - out_file.tell()] if filesize - out_file.tell() < 16
else out_file.write(self.fix_bytes(out_data))))
def encrypt_file(self, in_file_path, out_file_path, password = None):
#If a password is provided, generate new salt and create key and iv
if password is not None:
self.new_salt()
self.create_key_from_password(password)
else:
self._salt = None
#If key and iv are not provided are established above, bail out.
if self._key is None or self._iv is None:
return False
#Initialize encryption using key and iv
key_expander_256 = KeyExpander(256)
expanded_key = key_expander_256.expand(self._key)
aes_cipher_256 = AESCipher(expanded_key)
aes_cbc_256 = CBCMode(aes_cipher_256, 16)
aes_cbc_256.set_iv(self._iv)
#Get filesize of original file for storage in encrypted file
try:
filesize = os.stat(in_file_path)[6]
except:
return False
with open(in_file_path, 'rb') as in_file:
with open(out_file_path, 'wb') as out_file:
#Write salt if present
if self._salt is not None:
out_file.write(self._salt)
#Write filesize of original
out_file.write(struct.pack('L',filesize))
#Encrypt to eof
while 1:
in_data = in_file.read(16)
if not in_data:
self._salt = None
return True
else:
out_data = aes_cbc_256.encrypt_block(bytearray(in_data))
out_file.write(self.fix_bytes(out_data))