switch to cryptography

Fernet could not be used as it is not a streaming cipher.
CFB mode does not require padding, so removed padding code.

Depends-On: https://review.openstack.org/c/575199/
Change-Id: I14f58d9d473c20ce7863baa0b2adadbfda268b7a

doc/README.rst

@@ -124,7 +124,7 @@ Linux Requirements
 -  libffi-dev
 -  libssl-dev
 -  python-dev
--  pycrypto
+-  cryptography
 -  At least 128 MB of memory reserved for Freezer
 
 Windows Requirements
@@ -587,7 +587,7 @@ Freezer architectural components are the following:
 -  freezer client running on the node where the backups and restores are to be executed
 
 Freezer uses GNU Tar or Rsync algorithm under the hood to execute incremental backup and
-restore. When a key is provided, it uses OpenSSL or pycrypto module (OpenSSL compatible)
+restore. When a key is provided, it uses OpenSSL or cryptography module (OpenSSL compatible)
 to encrypt data. (AES-256-CFB)
 
 =============

freezer/engine/rsyncv2/rsyncv2.py

@@ -145,7 +145,6 @@ class Rsyncv2Engine(engine.BackupEngine):
         flushed_data += compressor.flush()
         if flushed_data and cipher:
             flushed_data = cipher.encrypt(flushed_data)
-            flushed_data += cipher.flush()
 
         return flushed_data
 

freezer/utils/crypt.py

@@ -14,12 +14,15 @@
 
 import hashlib
 
-from Crypto.Cipher import AES
-from Crypto import Random
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives.ciphers import algorithms
+from cryptography.hazmat.primitives.ciphers import Cipher
+from cryptography.hazmat.primitives.ciphers import modes
+from os import urandom
 
 SALT_HEADER = 'Salted__'
 AES256_KEY_LENGTH = 32
-BS = AES.block_size
+BS = 16  # static 16 bytes, 128 bits for AES
 
 
 class AESCipher(object):
@@ -56,40 +59,21 @@ class AESEncrypt(AESCipher):
 
     def __init__(self, pass_file):
         super(AESEncrypt, self).__init__(pass_file)
-        self._salt = Random.new().read(BS - len(SALT_HEADER))
+        self._salt = urandom(BS - len(SALT_HEADER))
         key, iv = self._derive_key_and_iv(self._password,
                                           self._salt,
                                           AES256_KEY_LENGTH,
                                           BS)
-        self.cipher = AES.new(key, AES.MODE_CFB, iv, segment_size=BS * 8)
-        self.remain = None
+        self.cipher = Cipher(algorithms.AES(key),
+                             modes.CFB(iv),
+                             backend=default_backend())
 
     def generate_header(self):
         return SALT_HEADER + self._salt
 
     def encrypt(self, data):
-        remain = self.remain
-        if remain:
-            data = remain + data
-            remain = None
-
-        extra_bytes = len(data) % BS
-        if extra_bytes:
-            remain = data[-extra_bytes:]
-            data = data[:-extra_bytes]
-
-        self.remain = remain
-        return self.cipher.encrypt(data)
-
-    def flush(self):
-        def pad(s):
-            return s + (BS - len(s) % BS) * chr(BS - len(s) % BS)
-
-        buff = self.remain
-        if buff:
-            return self.cipher.encrypt(pad(buff))
-
-        return b''
+        encryptor = self.cipher.encryptor()
+        return encryptor.update(data) + encryptor.finalize()
 
 
 class AESDecrypt(AESCipher):
@@ -105,17 +89,14 @@ class AESDecrypt(AESCipher):
                                           self._salt,
                                           AES256_KEY_LENGTH,
                                           BS)
-        self.cipher = AES.new(key, AES.MODE_CFB, iv, segment_size=BS * 8)
+        self.cipher = Cipher(algorithms.AES(key),
+                             modes.CFB(iv),
+                             backend=default_backend())
 
     @staticmethod
     def _prepare_salt(salt):
         return salt[len(SALT_HEADER):]
 
     def decrypt(self, data):
-        # def unpad(s):
-        #     return s[0:-ord(s[-1])]
-        #
-        # if last_block:
-        #     return unpad(self.cipher.decrypt(data))
-        # else:
-        return self.cipher.decrypt(data)
+        decryptor = self.cipher.decryptor()
+        return decryptor.update(data) + decryptor.finalize()

lower-constraints.txt

@@ -12,7 +12,7 @@ chardet==3.0.4
 cliff==2.11.0
 cmd2==0.8.1
 coverage==4.0
-cryptography==2.1.4
+cryptography==2.1
 ddt==1.0.1
 debtcollector==1.19.0
 decorator==4.2.1
@@ -74,7 +74,6 @@ prettytable==0.7.2
 psutil==3.2.2
 pyasn1==0.4.2
 pycparser==2.18
-pycrypto==2.6
 pyflakes==1.0.0
 Pygments==2.2.0
 pyinotify==0.9.6

requirements.txt

@@ -18,7 +18,7 @@ keystoneauth1>=3.4.0 # Apache-2.0
 os-brick>=2.2.0 # Apache-2.0
 oslo.service!=1.28.1,>=1.24.0 # Apache-2.0
 
-pycrypto>=2.6 # Public Domain
+cryptography>=2.1 # Apache-2.0
 PyMySQL>=0.7.6 # MIT License
 pymongo!=3.1,>=3.0.2 # Apache-2.0
 paramiko>=2.0.0 # LGPLv2.1+