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added PKCS #7 v1.5 padding

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updated secure_dumps to use SHA256
fixed secure_dumps using truncated encryption_key hash
fixed pad ignoring blocksize argument
This commit is contained in:
kelson
2016-08-17 16:08:05 -04:00
parent e87378b07f
commit 4b925bf297
2 changed files with 95 additions and 8 deletions
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gluon/utils.py
+61 -5
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@@ -157,25 +157,81 @@ def get_callable_argspec(fn):
return inspect.getargspec(inspectable)
def pad(s, n=32, padchar=b' '):
return s + (32 - len(s) % 32) * padchar
def pad(s, n=32):
# PKCS7v1.5 https://www.ietf.org/rfc/rfc2315.txt
padlen = n - len(s) % n
return s + bytes(bytearray(padlen * [padlen]))
def unpad(s, n=32):
padlen = s[-1]
if isinstance(padlen,str):
padlen = ord(padlen) # python2
if (padlen < 1) | (padlen > n): # avoid short-circuit
# return garbage to minimize side channels
return bytes(bytearray(len(s)*[0]))
return s[:-padlen]
def secure_dumps(data, encryption_key, hash_key=None, compression_level=None):
dump = pickle.dumps(data, pickle.HIGHEST_PROTOCOL)
if compression_level:
dump = zlib.compress(dump, compression_level)
encryption_key = to_bytes(encryption_key)
if not hash_key:
hash_key = hashlib.sha256(encryption_key).digest()
cipher, IV = AES_new(pad(encryption_key)[:32])
encrypted_data = base64.urlsafe_b64encode(IV + cipher.encrypt(pad(dump)))
signature = to_bytes(hmac.new(to_bytes(hash_key), encrypted_data, hashlib.sha256).hexdigest())
return b'hmac256:' + signature + b':' + encrypted_data
def secure_loads(data, encryption_key, hash_key=None, compression_level=None):
components = data.count(b':')
if components == 1:
return secure_loads_deprecated(data, encryption_key, hash_key, compression_level)
if components != 2:
return None
version,signature,encrypted_data = data.split(b':', 2)
if version != b'hmac256':
return None
encryption_key = to_bytes(encryption_key)
if not hash_key:
hash_key = hashlib.sha256(encryption_key).digest()
actual_signature = hmac.new(to_bytes(hash_key), encrypted_data, hashlib.sha256).hexdigest()
if not compare(to_native(signature), actual_signature):
return None
encrypted_data = base64.urlsafe_b64decode(encrypted_data)
IV, encrypted_data = encrypted_data[:16], encrypted_data[16:]
cipher, _ = AES_new(pad(encryption_key)[:32], IV=IV)
try:
data = unpad(cipher.decrypt(encrypted_data))
if compression_level:
data = zlib.decompress(data)
return pickle.loads(data)
except Exception as e:
return None
def __pad_deprecated(s, n=32, padchar=b' '):
return s + (32 - len(s) % 32) * padchar
def secure_dumps_deprecated(data, encryption_key, hash_key=None, compression_level=None):
encryption_key = to_bytes(encryption_key)
if not hash_key:
hash_key = sha1(encryption_key).hexdigest()
dump = pickle.dumps(data, pickle.HIGHEST_PROTOCOL)
if compression_level:
dump = zlib.compress(dump, compression_level)
key = pad(encryption_key)[:32]
key = __pad_deprecated(encryption_key)[:32]
cipher, IV = AES_new(key)
encrypted_data = base64.urlsafe_b64encode(IV + cipher.encrypt(pad(dump)))
signature = to_bytes(hmac.new(to_bytes(hash_key), encrypted_data, hashlib.md5).hexdigest())
return signature + b':' + encrypted_data
def secure_loads(data, encryption_key, hash_key=None, compression_level=None):
def secure_loads_deprecated(data, encryption_key, hash_key=None, compression_level=None):
encryption_key = to_bytes(encryption_key)
data = to_native(data)
if ':' not in data:
@@ -187,7 +243,7 @@ def secure_loads(data, encryption_key, hash_key=None, compression_level=None):
actual_signature = hmac.new(to_bytes(hash_key), encrypted_data, hashlib.md5).hexdigest()
if not compare(signature, actual_signature):
return None
key = pad(encryption_key)[:32]
key = __pad_deprecated(encryption_key)[:32]
encrypted_data = base64.urlsafe_b64decode(encrypted_data)
IV, encrypted_data = encrypted_data[:16], encrypted_data[16:]
cipher, _ = AES_new(key, IV=IV)