Add crypto module with HMAC-SHA256 implementation

This commit is contained in:
Kristóf Tóth 2018-07-15 17:27:35 +02:00
parent 16d98c75ca
commit eb2c3a8dd0
2 changed files with 48 additions and 0 deletions

47
lib/tfw/crypto.py Normal file
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@ -0,0 +1,47 @@
# Copyright (C) 2018 Avatao.com Innovative Learning Kft.
# All Rights Reserved. See LICENSE file for details.
from functools import wraps
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives.hashes import SHA256
from cryptography.hazmat.primitives.hmac import HMAC as _HMAC
from cryptography.exceptions import InvalidSignature
class HMAC:
def __init__(self, key, message):
self.key = key
self.message = message
self._hmac = _HMAC(
key=key,
algorithm=SHA256(),
backend=default_backend()
)
def _reload_if_finalized(f):
# pylint: disable=no-self-argument,not-callable
@wraps(f)
def wrapped(instance, *args, **kwargs):
if getattr(instance, '_finalized', False):
instance.__init__(instance.key, instance.message)
ret_val = f(instance, *args, **kwargs)
setattr(instance, '_finalized', True)
return ret_val
return wrapped
@property
@_reload_if_finalized
def signature(self):
self._hmac.update(self.message)
signature = self._hmac.finalize()
return signature
@_reload_if_finalized
def verify(self, signature):
self._hmac.update(self.message)
try:
self._hmac.verify(signature)
return True
except InvalidSignature:
return False

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@ -5,3 +5,4 @@ terminado==0.8.1
watchdog==0.8.3
PyYAML==3.12
Jinja2==2.10
cryptography==2.2.2