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# -*- coding: utf-8 -*-
# crypto.py
# Copyright (C) 2013 LEAP
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
Cryptographic utilities for Soledad.
"""
from hashlib import sha256
from leap.common.keymanager import openpgp
class NoSymmetricSecret(Exception):
"""
Raised when trying to get a hashed passphrase.
"""
class SoledadCrypto(object):
"""
General cryptographic functionality.
"""
def __init__(self, soledad):
"""
Initialize the crypto object.
@param soledad: A Soledad instance for key lookup.
@type soledad: leap.soledad.Soledad
"""
self._soledad = soledad
self._pgp = openpgp.OpenPGPScheme(self._soledad)
self._secret = None
def encrypt_sym(self, data, passphrase):
"""
Encrypt C{data} using a {password}.
@param data: the data to be encrypted
@type data: str
@param passphrase: the passphrase to use for encryption
@type passphrase: str
@return: the encrypted data
@rtype: str
"""
return openpgp.encrypt_sym(data, passphrase)
def decrypt_sym(self, data, passphrase):
"""
Decrypt data using symmetric secret.
@param data: the data to be decrypted
@type data: str
@param passphrase: the passphrase to use for decryption
@type passphrase: str
@return: the decrypted data
@rtype: str
"""
return openpgp.decrypt_sym(data, passphrase)
def is_encrypted(self, data):
"""
Test whether some chunk of data is a cyphertext.
@param data: the data to be tested
@type data: str
@return: whether the data is a cyphertext
@rtype: bool
"""
return openpgp.is_encrypted(data)
def is_encrypted_sym(self, data):
"""
Test whether some chunk of data was encrypted with a symmetric key.
@return: whether data is encrypted to a symmetric key
@rtype: bool
"""
return openpgp.is_encrypted_sym(data)
def passphrase_hash(self, suffix):
"""
Generate a passphrase for symmetric encryption.
The password is derived from the secret for symmetric encryption and
a C{suffix} that is appended to the secret prior to hashing.
@param suffix: Will be appended to the symmetric key before hashing.
@type suffix: str
@return: the passphrase
@rtype: str
@raise NoSymmetricSecret: if no symmetric secret was supplied.
"""
if self._secret is None:
raise NoSymmetricSecret()
return sha256('%s%s' % (self._secret, suffix)).hexdigest()
#
# secret setters/getters
#
def _get_secret(self):
return self._secret
def _set_secret(self, secret):
self._secret = secret
secret = property(_get_secret, _set_secret,
doc='The key used for symmetric encryption')
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