from getpass import getpass import hashlib import os import msgpack import zlib from pbkdf2 import pbkdf2 from Crypto.Cipher import AES from Crypto.Hash import SHA256, HMAC from Crypto.PublicKey import RSA from Crypto.Util import Counter from Crypto.Util.number import bytes_to_long from .helpers import IntegrityError, zero_pad from .oaep import OAEP class Keychain(object): FILE_ID = 'DARC KEYCHAIN' CREATE = '\1' READ = '\2' def __init__(self, path=None): self._key_cache = {} self.read_key = os.urandom(32) self.create_key = os.urandom(32) self.aes_id = self.rsa_read = self.rsa_create = None self.path = path if path: self.open(path) def get_chunkify_seed(self): return bytes_to_long(self.aes_id[:4]) def open(self, path): print 'Opening keychain "%s"' % path with open(path, 'rb') as fd: if fd.read(len(self.FILE_ID)) != self.FILE_ID: raise ValueError('Not a keychain') cdata = fd.read() self.password = '' data = self.decrypt_keychain(cdata, '') while not data: self.password = getpass('Keychain password: ') if not self.password: raise Exception('Keychain decryption failed') data = self.decrypt_keychain(cdata, self.password) if not data: print 'Incorrect password' chain = msgpack.unpackb(data) assert chain['version'] == 1 self.aes_id = chain['aes_id'] self.rsa_read = RSA.importKey(chain['rsa_read']) self.rsa_create = RSA.importKey(chain['rsa_create']) self.read_encrypted = OAEP(256, hash=SHA256).encode(self.read_key, os.urandom(32)) self.read_encrypted = zero_pad(self.rsa_read.encrypt(self.read_encrypted, '')[0], 256) self.create_encrypted = OAEP(256, hash=SHA256).encode(self.create_key, os.urandom(32)) self.create_encrypted = zero_pad(self.rsa_create.encrypt(self.create_encrypted, '')[0], 256) def encrypt(self, data, password): salt = os.urandom(32) iterations = 2000 key = pbkdf2(password, salt, 32, iterations, hashlib.sha256) hash = HMAC.new(key, data, SHA256).digest() cdata = AES.new(key, AES.MODE_CTR, counter=Counter.new(128)).encrypt(data) d = { 'version': 1, 'salt': salt, 'iterations': iterations, 'algorithm': 'SHA256', 'hash': hash, 'data': cdata, } return msgpack.packb(d) def decrypt_keychain(self, data, password): d = msgpack.unpackb(data) assert d['version'] == 1 assert d['algorithm'] == 'SHA256' key = pbkdf2(password, d['salt'], 32, d['iterations'], hashlib.sha256) data = AES.new(key, AES.MODE_CTR, counter=Counter.new(128)).decrypt(d['data']) if HMAC.new(key, data, SHA256).digest() != d['hash']: return None return data def save(self, path, password): chain = { 'version': 1, 'aes_id': self.aes_id, 'rsa_read': self.rsa_read.exportKey('PEM'), 'rsa_create': self.rsa_create.exportKey('PEM'), } data = self.encrypt(msgpack.packb(chain), password) with open(path, 'wb') as fd: fd.write(self.FILE_ID) fd.write(data) print 'Key chain "%s" saved' % path def restrict(self, path): if os.path.exists(path): print '%s already exists' % path return 1 self.rsa_read = self.rsa_read.publickey() self.save(path, self.password) return 0 def chpass(self): password, password2 = 1, 2 while password != password2: password = getpass('New password: ') password2 = getpass('New password again: ') if password != password2: print 'Passwords do not match' self.save(self.path, password) return 0 @staticmethod def generate(path): if os.path.exists(path): print '%s already exists' % path return 1 password, password2 = 1, 2 while password != password2: password = getpass('Keychain password: ') password2 = getpass('Keychain password again: ') if password != password2: print 'Passwords do not match' chain = Keychain() print 'Generating keychain' chain.aes_id = os.urandom(32) chain.rsa_read = RSA.generate(2048) chain.rsa_create = RSA.generate(2048) chain.save(path, password) return 0 def id_hash(self, data): return HMAC.new(self.aes_id, data, SHA256).digest() def encrypt_read(self, data): data = zlib.compress(data) hash = self.id_hash(data) counter = Counter.new(128, initial_value=bytes_to_long(hash[:16]), allow_wraparound=True) data = AES.new(self.read_key, AES.MODE_CTR, '', counter=counter).encrypt(data) return ''.join((self.READ, self.read_encrypted, hash, data)), hash def encrypt_create(self, data): data = zlib.compress(data) hash = self.id_hash(data) counter = Counter.new(128, initial_value=bytes_to_long(hash[:16]), allow_wraparound=True) data = AES.new(self.create_key, AES.MODE_CTR, '', counter=counter).encrypt(data) return ''.join((self.CREATE, self.create_encrypted, hash, data)), hash def decrypt_key(self, data, rsa_key): try: return self._key_cache[data] except KeyError: self._key_cache[data] = OAEP(256, hash=SHA256).decode(rsa_key.decrypt(data)) return self._key_cache[data] def decrypt(self, data): type = data[0] if type == self.READ: key = self.decrypt_key(data[1:257], self.rsa_read) hash = data[257:289] counter = Counter.new(128, initial_value=bytes_to_long(hash[:16]), allow_wraparound=True) data = AES.new(key, AES.MODE_CTR, counter=counter).decrypt(data[289:]) if self.id_hash(data) != hash: raise IntegrityError('decryption failed') return zlib.decompress(data), hash elif type == self.CREATE: key = self.decrypt_key(data[1:257], self.rsa_create) hash = data[257:289] counter = Counter.new(128, initial_value=bytes_to_long(hash[:16]), allow_wraparound=True) data = AES.new(key, AES.MODE_CTR, '', counter=counter).decrypt(data[289:]) if self.id_hash(data) != hash: raise IntegrityError('decryption failed') return zlib.decompress(data), hash else: raise Exception('Unknown pack type %d found' % ord(type))