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#
# Copyright (c) 2014 ThoughtWorks, Inc.
#
# Pixelated is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Pixelated 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with Pixelated. If not, see <http://www.gnu.org/licenses/>.
import io
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
from leap.soledad.client.crypto import decrypt_sym
from leap.soledad.client.crypto import EncryptionMethods
from whoosh.util import random_name
class EncryptedFileStorage(FileStorage):
def __init__(self, path, masterkey=None):
self.masterkey = masterkey[:32]
self.signkey = masterkey[32:]
self._tmp_storage = self.temp_storage
self.length_cache = {}
FileStorage.__init__(self, path, supports_mmap=False)
def open_file(self, name, **kwargs):
return self._open_encrypted_file(name, onclose=self._encrypt_index_on_close(name))
def create_file(self, name, excl=False, mode="w+b", **kwargs):
f = StructFile(io.BytesIO(), name=name, onclose=self._encrypt_index_on_close(name))
f.is_real = False
return f
def temp_storage(self, name=None):
name = name or "%s.tmp" % random_name()
path = os.path.join(self.folder, name)
return EncryptedFileStorage(path, self.masterkey).create()
def file_length(self, name):
return self.length_cache[name][0]
def gen_mac(self, iv, ciphertext):
verifiable_payload = ''.join((iv, ciphertext))
return hmac.new(self.signkey, verifiable_payload, sha256).digest()
def encrypt(self, content):
iv, ciphertext = encrypt_sym(content, self.masterkey, EncryptionMethods.XSALSA20)
mac = self.gen_mac(iv, 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(iv, 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 = 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 = 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 = self.decrypt(file_content)
self.length_cache[name] = (len(decrypted), sha256(decrypted).digest())
return BufferFile(buffer(decrypted), name=name, onclose=onclose)
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