root / snf-cyclades-app / synnefo / db / aes_encrypt.py @ 91884d63
History | View | Annotate | Download (3.5 kB)
1 |
# Copyright 2012, 2013 GRNET S.A. All rights reserved.
|
---|---|
2 |
#
|
3 |
# Redistribution and use in source and binary forms, with or without
|
4 |
# modification, are permitted provided that the following conditions
|
5 |
# are met:
|
6 |
#
|
7 |
# 1. Redistributions of source code must retain the above copyright
|
8 |
# notice, this list of conditions and the following disclaimer.
|
9 |
#
|
10 |
# 2. Redistributions in binary form must reproduce the above copyright
|
11 |
# notice, this list of conditions and the following disclaimer in the
|
12 |
# documentation and/or other materials provided with the distribution.
|
13 |
#
|
14 |
# THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
15 |
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
16 |
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
17 |
# ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
18 |
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
19 |
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
20 |
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
21 |
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
22 |
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
23 |
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
24 |
# SUCH DAMAGE.
|
25 |
#
|
26 |
# The views and conclusions contained in the software and documentation are
|
27 |
# those of the authors and should not be interpreted as representing official
|
28 |
# policies, either expressed or implied, of GRNET S.A.
|
29 |
|
30 |
from binascii import b2a_base64, a2b_base64 |
31 |
from Crypto.Cipher import AES |
32 |
from Crypto import Random |
33 |
from random import choice |
34 |
from string import letters, digits |
35 |
from synnefo.settings import SECRET_ENCRYPTION_KEY |
36 |
|
37 |
|
38 |
DB_ENCRYPTED_FIELD_PREFIX = 'encrypted'
|
39 |
SALT_LEN = 8
|
40 |
|
41 |
|
42 |
def _pad_secret(secret, blocksize=32, padding='}'): |
43 |
len_secret = len(secret)
|
44 |
if len_secret > 32: |
45 |
raise ValueError('Encryption key must be smaller than 32 bytes') |
46 |
if not len_secret in (16, 24, 32): |
47 |
return secret + (blocksize - len(secret)) * padding |
48 |
return secret
|
49 |
|
50 |
|
51 |
def encrypt(s, iv): |
52 |
obj = AES.new(_pad_secret(SECRET_ENCRYPTION_KEY), AES.MODE_CFB, iv) |
53 |
return obj.encrypt(s)
|
54 |
|
55 |
|
56 |
def decrypt(s, iv): |
57 |
obj = AES.new(_pad_secret(SECRET_ENCRYPTION_KEY), AES.MODE_CFB, iv) |
58 |
return obj.decrypt(s)
|
59 |
|
60 |
|
61 |
def encrypt_db_charfield(plaintext): |
62 |
if not plaintext: |
63 |
return plaintext
|
64 |
salt = "".join([choice(letters + digits) for i in xrange(SALT_LEN)]) |
65 |
|
66 |
iv = Random.get_random_bytes(16)
|
67 |
plaintext = "%s%s" % (salt, plaintext)
|
68 |
# Encrypt and convert to binary
|
69 |
ciphertext = b2a_base64(encrypt(plaintext, iv)) |
70 |
iv = b2a_base64(iv) |
71 |
# Append prefix,salt and return encoded value
|
72 |
final = '%s:%s:%s$%s' % (DB_ENCRYPTED_FIELD_PREFIX, iv, salt, ciphertext)
|
73 |
return final.encode('utf8') |
74 |
|
75 |
|
76 |
def decrypt_db_charfield(ciphertext): |
77 |
if not ciphertext: |
78 |
return ciphertext
|
79 |
has_prefix = ciphertext.startswith(DB_ENCRYPTED_FIELD_PREFIX + ':')
|
80 |
if not has_prefix: # Non-encoded value |
81 |
return ciphertext
|
82 |
else:
|
83 |
_, iv, ciphertext = ciphertext.split(':')
|
84 |
|
85 |
pure_salt, encrypted = ciphertext.split('$')
|
86 |
iv = a2b_base64(iv) |
87 |
|
88 |
plaintext = decrypt(a2b_base64(encrypted), iv) |
89 |
|
90 |
salt = plaintext[:SALT_LEN] |
91 |
plaintext = plaintext[SALT_LEN:] |
92 |
|
93 |
if salt != pure_salt:
|
94 |
# Cannot decrtypt password
|
95 |
raise CorruptedPassword("Cannot decrypt password. Check the key") |
96 |
else:
|
97 |
return plaintext
|
98 |
|
99 |
|
100 |
class CorruptedPassword(Exception): |
101 |
pass
|