From ab2fb69e74464d5424d7e3429d4e787586cd00e8 Mon Sep 17 00:00:00 2001 From: Victor Shyba Date: Wed, 14 Jan 2015 17:14:35 -0300 Subject: for #227, MAC on encrypted storage --- .../pixelated/support/encrypted_file_storage.py | 29 +++++++++++++++++----- 1 file changed, 23 insertions(+), 6 deletions(-) (limited to 'service/pixelated/support') diff --git a/service/pixelated/support/encrypted_file_storage.py b/service/pixelated/support/encrypted_file_storage.py index 04f2e6e8..49a67627 100644 --- a/service/pixelated/support/encrypted_file_storage.py +++ b/service/pixelated/support/encrypted_file_storage.py @@ -15,9 +15,10 @@ # along with Pixelated. If not, see . import io -from hashlib import sha512 +from hashlib import sha256 import os +import hmac from whoosh.filedb.filestore import FileStorage from whoosh.filedb.structfile import StructFile, BufferFile from leap.soledad.client.crypto import encrypt_sym @@ -28,7 +29,8 @@ from whoosh.util import random_name class EncryptedFileStorage(FileStorage): def __init__(self, path, masterkey=None): - self.masterkey = masterkey + self.masterkey = masterkey[:32] + self.signkey = masterkey[32:] self._tmp_storage = self.temp_storage self.length_cache = {} FileStorage.__init__(self, path, supports_mmap=False) @@ -49,21 +51,36 @@ class EncryptedFileStorage(FileStorage): def file_length(self, name): return self.length_cache[name][0] + def gen_mac(self, ciphertext): + return hmac.new(self.signkey, ciphertext, sha256).digest() + + def encrypt(self, content): + iv, ciphertext = encrypt_sym(content, self.masterkey, EncryptionMethods.XSALSA20) + mac = self.gen_mac(ciphertext) + return ''.join((mac, iv, ciphertext)) + + def decrypt(self, payload): + payload_mac, iv, ciphertext = payload[:32], payload[32:65], payload[65:] + generated_mac = self.gen_mac(ciphertext) + if sha256(payload_mac).digest() != sha256(generated_mac).digest(): + raise Exception("EncryptedFileStorage - Error opening file. Wrong MAC") + return decrypt_sym(ciphertext, self.masterkey, EncryptionMethods.XSALSA20, iv=iv) + def _encrypt_index_on_close(self, name): def wrapper(struct_file): struct_file.seek(0) content = struct_file.file.read() - file_hash = sha512(content).digest() + file_hash = sha256(content).digest() if name in self.length_cache and file_hash == self.length_cache[name][1]: return self.length_cache[name] = (len(content), file_hash) - encrypted_content = ''.join(encrypt_sym(content, self.masterkey, EncryptionMethods.XSALSA20)) + encrypted_content = self.encrypt(content) with open(self._fpath(name), 'w+b') as f: f.write(encrypted_content) return wrapper def _open_encrypted_file(self, name, onclose=lambda x: None): file_content = open(self._fpath(name), "rb").read() - decrypted = decrypt_sym(file_content[33:], self.masterkey, EncryptionMethods.XSALSA20, iv=file_content[:33]) - self.length_cache[name] = (len(decrypted), sha512(decrypted).digest()) + decrypted = self.decrypt(file_content) + self.length_cache[name] = (len(decrypted), sha256(decrypted).digest()) return BufferFile(buffer(decrypted), name=name, onclose=onclose) -- cgit v1.2.3