diff options
Diffstat (limited to 'client/src/leap/soledad/client/crypto.py')
| -rw-r--r-- | client/src/leap/soledad/client/crypto.py | 209 |
1 files changed, 113 insertions, 96 deletions
diff --git a/client/src/leap/soledad/client/crypto.py b/client/src/leap/soledad/client/crypto.py index a6372107..c1f65171 100644 --- a/client/src/leap/soledad/client/crypto.py +++ b/client/src/leap/soledad/client/crypto.py @@ -1,6 +1,6 @@ # -*- coding: utf-8 -*- # crypto.py -# Copyright (C) 2013 LEAP +# Copyright (C) 2013,2014 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 @@ -36,6 +36,8 @@ from leap.soledad.common import ( soledad_assert_type, ) +MAC_KEY_LENGTH = 64 + class EncryptionMethods(object): """ @@ -59,13 +61,116 @@ class NoSymmetricSecret(Exception): """ +def encrypt_sym(data, key, method): + """ + Encrypt C{data} using a {password}. + + Currently, the only encryption methods supported are AES-256 in CTR + mode and XSalsa20. + + :param data: The data to be encrypted. + :type data: str + :param key: The key used to encrypt C{data} (must be 256 bits long). + :type key: str + :param method: The encryption method to use. + :type method: str + + :return: A tuple with the initial value and the encrypted data. + :rtype: (long, str) + """ + soledad_assert_type(key, str) + + soledad_assert( + len(key) == 32, # 32 x 8 = 256 bits. + 'Wrong key size: %s bits (must be 256 bits long).' % + (len(key) * 8)) + iv = None + # AES-256 in CTR mode + if method == EncryptionMethods.AES_256_CTR: + iv = os.urandom(16) + ciphertext = AES(key=key, iv=iv).process(data) + # XSalsa20 + elif method == EncryptionMethods.XSALSA20: + iv = os.urandom(24) + ciphertext = XSalsa20(key=key, iv=iv).process(data) + else: + # raise if method is unknown + raise UnknownEncryptionMethod('Unkwnown method: %s' % method) + return binascii.b2a_base64(iv), ciphertext + + +def decrypt_sym(data, key, method, **kwargs): + """ + Decrypt data using symmetric secret. + + Currently, the only encryption method supported is AES-256 CTR mode. + + :param data: The data to be decrypted. + :type data: str + :param key: The key used to decrypt C{data} (must be 256 bits long). + :type key: str + :param method: The encryption method to use. + :type method: str + :param kwargs: Other parameters specific to each encryption method. + :type kwargs: dict + + :return: The decrypted data. + :rtype: str + """ + soledad_assert_type(key, str) + # assert params + soledad_assert( + len(key) == 32, # 32 x 8 = 256 bits. + 'Wrong key size: %s (must be 256 bits long).' % len(key)) + soledad_assert( + 'iv' in kwargs, + '%s needs an initial value.' % method) + # AES-256 in CTR mode + if method == EncryptionMethods.AES_256_CTR: + return AES( + key=key, iv=binascii.a2b_base64(kwargs['iv'])).process(data) + elif method == EncryptionMethods.XSALSA20: + return XSalsa20( + key=key, iv=binascii.a2b_base64(kwargs['iv'])).process(data) + + # raise if method is unknown + raise UnknownEncryptionMethod('Unkwnown method: %s' % method) + + +def doc_mac_key(doc_id, secret): + """ + Generate a key for calculating a MAC for a document whose id is + C{doc_id}. + + The key is derived using HMAC having sha256 as underlying hash + function. The key used for HMAC is the first MAC_KEY_LENGTH characters + of Soledad's storage secret. The HMAC message is C{doc_id}. + + :param doc_id: The id of the document. + :type doc_id: str + + :param secret: soledad secret storage + :type secret: Soledad.storage_secret + + :return: The key. + :rtype: str + + :raise NoSymmetricSecret: if no symmetric secret was supplied. + """ + if secret is None: + raise NoSymmetricSecret() + + return hmac.new( + secret[:MAC_KEY_LENGTH], + doc_id, + hashlib.sha256).digest() + + class SoledadCrypto(object): """ General cryptographic functionality. """ - MAC_KEY_LENGTH = 64 - def __init__(self, soledad): """ Initialize the crypto object. @@ -77,78 +182,14 @@ class SoledadCrypto(object): def encrypt_sym(self, data, key, method=EncryptionMethods.AES_256_CTR): - """ - Encrypt C{data} using a {password}. - - Currently, the only encryption method supported is AES-256 CTR mode. - - :param data: The data to be encrypted. - :type data: str - :param key: The key used to encrypt C{data} (must be 256 bits long). - :type key: str - :param method: The encryption method to use. - :type method: str - - :return: A tuple with the initial value and the encrypted data. - :rtype: (long, str) - """ - soledad_assert_type(key, str) - - soledad_assert( - len(key) == 32, # 32 x 8 = 256 bits. - 'Wrong key size: %s bits (must be 256 bits long).' % - (len(key) * 8)) - iv = None - # AES-256 in CTR mode - if method == EncryptionMethods.AES_256_CTR: - iv = os.urandom(16) - ciphertext = AES(key=key, iv=iv).process(data) - # XSalsa20 - elif method == EncryptionMethods.XSALSA20: - iv = os.urandom(24) - ciphertext = XSalsa20(key=key, iv=iv).process(data) - else: - # raise if method is unknown - raise UnknownEncryptionMethod('Unkwnown method: %s' % method) - return binascii.b2a_base64(iv), ciphertext + return encrypt_sym(data, key, method) def decrypt_sym(self, data, key, method=EncryptionMethods.AES_256_CTR, **kwargs): - """ - Decrypt data using symmetric secret. - - Currently, the only encryption method supported is AES-256 CTR mode. - - :param data: The data to be decrypted. - :type data: str - :param key: The key used to decrypt C{data} (must be 256 bits long). - :type key: str - :param method: The encryption method to use. - :type method: str - :param kwargs: Other parameters specific to each encryption method. - :type kwargs: dict + return decrypt_sym(data, key, method, **kwargs) - :return: The decrypted data. - :rtype: str - """ - soledad_assert_type(key, str) - # assert params - soledad_assert( - len(key) == 32, # 32 x 8 = 256 bits. - 'Wrong key size: %s (must be 256 bits long).' % len(key)) - soledad_assert( - 'iv' in kwargs, - '%s needs an initial value.' % method) - # AES-256 in CTR mode - if method == EncryptionMethods.AES_256_CTR: - return AES( - key=key, iv=binascii.a2b_base64(kwargs['iv'])).process(data) - elif method == EncryptionMethods.XSALSA20: - return XSalsa20( - key=key, iv=binascii.a2b_base64(kwargs['iv'])).process(data) - - # raise if method is unknown - raise UnknownEncryptionMethod('Unkwnown method: %s' % method) + def doc_mac_key(self, doc_id, secret): + return doc_mac_key(doc_id, self.secret) def doc_passphrase(self, doc_id): """ @@ -173,35 +214,11 @@ class SoledadCrypto(object): raise NoSymmetricSecret() return hmac.new( self.secret[ - self.MAC_KEY_LENGTH: + MAC_KEY_LENGTH: self._soledad.REMOTE_STORAGE_SECRET_LENGTH], doc_id, hashlib.sha256).digest() - def doc_mac_key(self, doc_id): - """ - Generate a key for calculating a MAC for a document whose id is - C{doc_id}. - - The key is derived using HMAC having sha256 as underlying hash - function. The key used for HMAC is the first MAC_KEY_LENGTH characters - of Soledad's storage secret. The HMAC message is C{doc_id}. - - :param doc_id: The id of the document. - :type doc_id: str - - :return: The key. - :rtype: str - - :raise NoSymmetricSecret: if no symmetric secret was supplied. - """ - if self.secret is None: - raise NoSymmetricSecret() - return hmac.new( - self.secret[:self.MAC_KEY_LENGTH], - doc_id, - hashlib.sha256).digest() - # # secret setters/getters # |