# -*- coding: utf-8 -*- """ Soledad - Synchronization Of Locally Encrypted Data Among Devices. Soledad is the part of LEAP that manages storage and synchronization of application data. It is built on top of U1DB reference Python API and implements (1) a SQLCipher backend for local storage in the client, (2) a SyncTarget that encrypts data to the user's private OpenPGP key before syncing, and (3) a CouchDB backend for remote storage in the server side. """ import os import string import random import hmac import configparser import re try: import simplejson as json except ImportError: import json # noqa from leap.soledad.backends import sqlcipher from leap.soledad.util import GPGWrapper from leap.soledad.backends.leap_backend import ( LeapDocument, DocumentNotEncrypted, ) from leap.soledad.shared_db import SoledadSharedDatabase class KeyDoesNotExist(Exception): """ Soledad attempted to find a key that does not exist locally. """ class KeyAlreadyExists(Exception): """ Soledad attempted to create a key that already exists locally. """ #----------------------------------------------------------------------------- # Soledad: local encrypted storage and remote encrypted sync. #----------------------------------------------------------------------------- class Soledad(object): """ Soledad provides encrypted data storage and sync. A Soledad instance is used to store and retrieve data in a local encrypted database and synchronize this database with Soledad server. This class is also responsible for bootstrapping users' account by creating OpenPGP keys and other cryptographic secrets and/or storing/fetching them on Soledad server. """ # other configs SECRET_LENGTH = 50 DEFAULT_CONF = { 'gnupg_home': '%s/gnupg', 'secret_path': '%s/secret.gpg', 'local_db_path': '%s/soledad.u1db', 'config_file': '%s/soledad.ini', 'shared_db_url': '', } # TODO: separate username from provider, currently in user_email. def __init__(self, user_email, prefix=None, gnupg_home=None, secret_path=None, local_db_path=None, config_file=None, shared_db_url=None, auth_token=None, bootstrap=True): """ Initialize crypto and dbs. :param user_email: Email address of the user (username@provider). :param prefix: Path to use as prefix for files. :param gnupg_home: Home directory for gnupg. :param secret_path: Path for storing gpg-encrypted key used for symmetric encryption. :param local_db_path: Path for local encrypted storage db. :param config_file: Path for configuration file. :param shared_db_url: URL for shared Soledad DB for key storage and unauth retrieval. :param auth_token: Authorization token for accessing remote databases. :param bootstrap: True/False, should bootstrap keys? """ # TODO: allow for fingerprint enforcing. self._user_email = user_email self._auth_token = auth_token self._init_config( {'prefix': prefix, 'gnupg_home': gnupg_home, 'secret_path': secret_path, 'local_db_path': local_db_path, 'config_file': config_file, 'shared_db_url': shared_db_url, } ) if self.shared_db_url: # TODO: eliminate need to create db here. self._shared_db = SoledadSharedDatabase.open_database( self.shared_db_url, True, token=auth_token) if bootstrap: self._bootstrap() def _bootstrap(self): """ Bootstrap local Soledad instance. Soledad Client bootstrap is the following sequence of stages: 1. Key loading/generation: guarantees key is either loaded from server or generated locally. 2. Key copy verification: guarantees our copy of keys is identical to server's copy. This method decides which bootstrap stages have already been performed and performs the missing ones in order. """ # TODO: make sure key storage always happens (even if this method is # interrupted). # TODO: write tests for bootstrap stages. self._init_dirs() self._gpg = GPGWrapper(gnupghome=self.gnupg_home) # bootstrap stage 1 if self._has_keys(): self._load_keys() else: doc = self._get_keys_doc() if not doc: self._init_keys() else: self._set_privkey(self.decrypt(doc.content['_privkey'], passphrase=self._user_hash())) self._set_symkey(self.decrypt(doc.content['_symkey'])) # bootstrap stage 2 self._assert_server_keys() self._init_db() def _init_config(self, param_conf): """ Initialize configuration, with precedence order give by: instance parameters > config file > default values. """ # TODO: write tests for _init_config() self.prefix = param_conf['prefix'] or \ os.environ['HOME'] + '/.config/leap/soledad' m = re.compile('.*%s.*') for key, default_value in self.DEFAULT_CONF.iteritems(): val = param_conf[key] or default_value if m.match(val): val = val % self.prefix setattr(self, key, val) # get config from file # TODO: sanitize options from config file. config = configparser.ConfigParser() config.read(self.config_file) if 'soledad-client' in config: for key in self.DEFAULT_CONF: if key in config['soledad-client'] and not param_conf[key]: setattr(self, key, config['soledad-client'][key]) def _init_dirs(self): """ Create work directories. """ if not os.path.isdir(self.prefix): os.makedirs(self.prefix) def _init_keys(self): """ Generate (if needed) and load OpenPGP keypair and secret for symmetric encryption. """ # TODO: write tests for methods below. # load/generate OpenPGP keypair if not self._has_privkey(): self._gen_privkey() self._load_privkey() # load/generate secret if not self._has_symkey(): self._gen_symkey() self._load_symkey() def _init_db(self): """ Initialize the database for local storage . """ # instantiate u1db # TODO: verify if secret for sqlcipher should be the same as the # one for symmetric encryption. self._db = sqlcipher.open( self.local_db_path, self._symkey, create=True, document_factory=LeapDocument, soledad=self) def close(self): """ Close underlying U1DB database. """ self._db.close() #------------------------------------------------------------------------- # Management of secret for symmetric encryption #------------------------------------------------------------------------- # TODO: refactor the following methods to somewhere out of here # (SoledadCrypto, maybe?) def _has_symkey(self): """ Verify if secret for symmetric encryption exists in a local encrypted file. """ # does the file exist in disk? if not os.path.isfile(self.secret_path): return False # is it asymmetrically encrypted? f = open(self.secret_path, 'r') content = f.read() if not self.is_encrypted_asym(content): raise DocumentNotEncrypted( "File %s is not encrypted!" % self.secret_path) # can we decrypt it? fp = self._gpg.encrypted_to(content)['fingerprint'] if fp != self._fingerprint: raise KeyDoesNotExist("Secret for symmetric encryption is " "encrypted to key with fingerprint '%s' " "which we don't have." % fp) return True def _load_symkey(self): """ Load secret for symmetric encryption from local encrypted file. """ if not self._has_symkey(): raise KeyDoesNotExist("Tried to load key for symmetric " "encryption but it does not exist on disk.") try: with open(self.secret_path) as f: self._symkey = str(self._gpg.decrypt(f.read())) except IOError: raise IOError('Failed to open secret file %s.' % self.secret_path) def _gen_symkey(self): """ Generate a secret for symmetric encryption and store in a local encrypted file. """ self._set_symkey(''.join( random.choice( string.ascii_letters + string.digits) for x in range(self.SECRET_LENGTH))) def _set_symkey(self, symkey): if self._has_symkey(): raise KeyAlreadyExists("Tried to set the value of the key for " "symmetric encryption but it already " "exists on disk.") self._symkey = symkey self._store_symkey() def _store_symkey(self): ciphertext = self._gpg.encrypt(self._symkey, self._fingerprint, self._fingerprint) f = open(self.secret_path, 'w') f.write(str(ciphertext)) f.close() #------------------------------------------------------------------------- # Management of OpenPGP keypair #------------------------------------------------------------------------- def _has_privkey(self): """ Verify if there exists an OpenPGP keypair for this user. """ try: self._load_privkey() return True except: return False def _gen_privkey(self): """ Generate an OpenPGP keypair for this user. """ if self._has_privkey(): raise KeyAlreadyExists("Tried to generate OpenPGP keypair but it " "already exists on disk.") params = self._gpg.gen_key_input( key_type='RSA', key_length=4096, name_real=self._user_email, name_email=self._user_email, name_comment='Generated by LEAP Soledad.') fingerprint = self._gpg.gen_key(params).fingerprint return self._load_privkey(fingerprint) def _set_privkey(self, raw_data): if self._has_privkey(): raise KeyAlreadyExists("Tried to generate OpenPGP keypair but it " "already exists on disk.") fingerprint = self._gpg.import_keys(raw_data).fingerprints[0] return self._load_privkey(fingerprint) def _load_privkey(self, fingerprint=None): """ Find fingerprint for this user's OpenPGP keypair. """ # TODO: guarantee encrypted storage of private keys. try: if fingerprint: self._fingerprint = self._gpg.find_key_by_fingerprint( fingerprint, secret=True)['fingerprint'] else: self._fingerprint = self._gpg.find_key_by_email( self._user_email, secret=True)['fingerprint'] return self._fingerprint except LookupError: raise KeyDoesNotExist("Tried to load OpenPGP keypair but it does " "not exist on disk.") def publish_pubkey(self, keyserver): """ Publish OpenPGP public key to a keyserver. """ # TODO: this has to talk to LEAP's Nickserver. pass #------------------------------------------------------------------------- # General crypto utility methods. #------------------------------------------------------------------------- def _has_keys(self): return self._has_privkey() and self._has_symkey() def _load_keys(self): self._load_privkey() self._load_symkey() def _gen_keys(self): self._gen_privkey() self._gen_symkey() def _user_hash(self): return hmac.new(self._user_email, 'user').hexdigest() def _get_keys_doc(self): return self._shared_db.get_doc_unauth(self._user_hash()) def _assert_server_keys(self): """ Assert our key copies are the same as server's ones. """ assert self._has_keys() doc = self._get_keys_doc() if doc: remote_privkey = self.decrypt(doc.content['_privkey'], # TODO: change passphrase. passphrase=self._user_hash()) remote_symkey = self.decrypt(doc.content['_symkey']) result = self._gpg.import_keys(remote_privkey) # TODO: is the following behaviour expected in any scenario? assert result.fingerprints[0] == self._fingerprint assert remote_symkey == self._symkey else: privkey = self._gpg.export_keys(self._fingerprint, secret=True) content = { '_privkey': self.encrypt(privkey, # TODO: change passphrase passphrase=self._user_hash(), symmetric=True), '_symkey': self.encrypt(self._symkey), } doc = LeapDocument(doc_id=self._user_hash(), soledad=self) doc.content = content self._shared_db.put_doc(doc) def _assert_remote_keys(self): privkey, symkey = self._retrieve_keys() #------------------------------------------------------------------------- # Data encryption and decryption #------------------------------------------------------------------------- def encrypt(self, data, sign=None, passphrase=None, symmetric=False): """ Encrypt data. """ return str(self._gpg.encrypt(data, self._fingerprint, sign=sign, passphrase=passphrase, symmetric=symmetric)) def encrypt_symmetric(self, doc_id, data, sign=None): """ Encrypt data using symmetric secret. """ return self.encrypt(data, sign=sign, passphrase=self._hmac_passphrase(doc_id), symmetric=True) def decrypt(self, data, passphrase=None): """ Decrypt data. """ return str(self._gpg.decrypt(data, passphrase=passphrase)) def decrypt_symmetric(self, doc_id, data): """ Decrypt data using symmetric secret. """ return self.decrypt(data, passphrase=self._hmac_passphrase(doc_id)) def _hmac_passphrase(self, doc_id): return hmac.new(self._symkey, doc_id).hexdigest() def is_encrypted(self, data): return self._gpg.is_encrypted(data) def is_encrypted_sym(self, data): return self._gpg.is_encrypted_sym(data) def is_encrypted_asym(self, data): return self._gpg.is_encrypted_asym(data) #------------------------------------------------------------------------- # Document storage, retrieval and sync #------------------------------------------------------------------------- # TODO: refactor the following methods to somewhere out of here # (SoledadLocalDatabase, maybe?) def put_doc(self, doc): """ Update a document in the local encrypted database. """ return self._db.put_doc(doc) def delete_doc(self, doc): """ Delete a document from the local encrypted database. """ return self._db.delete_doc(doc) def get_doc(self, doc_id, include_deleted=False): """ Retrieve a document from the local encrypted database. """ return self._db.get_doc(doc_id, include_deleted=include_deleted) def get_docs(self, doc_ids, check_for_conflicts=True, include_deleted=False): """ Get the content for many documents. """ return self._db.get_docs(doc_ids, check_for_conflicts=check_for_conflicts, include_deleted=include_deleted) def create_doc(self, content, doc_id=None): """ Create a new document in the local encrypted database. """ return self._db.create_doc(content, doc_id=doc_id) def get_doc_conflicts(self, doc_id): """ Get the list of conflicts for the given document. """ return self._db.get_doc_conflicts(doc_id) def resolve_doc(self, doc, conflicted_doc_revs): """ Mark a document as no longer conflicted. """ return self._db.resolve_doc(doc, conflicted_doc_revs) def sync(self, url): """ Synchronize the local encrypted database with LEAP server. """ # TODO: create authentication scheme for sync with server. return self._db.sync(url, creds=None, autocreate=True) #------------------------------------------------------------------------- # Recovery document export and import #------------------------------------------------------------------------- def export_recovery_document(self, passphrase): """ Exports username, provider, private key and key for symmetric encryption, optionally encrypted with a password. The LEAP client gives the user the option to export a text file with a complete copy of their private keys and authorization information, either password protected or not. This "recovery document" can be printed or saved electronically as the user sees fit. If the user needs to recover their data, they can load this recover document into any LEAP client. The user can also type the recovery document in manually, although it will be long and very painful to copy manually. Contents of recovery document: - username - provider - private key. - key for symmetric encryption """ data = json.dumps({ 'user_email': self._user_email, 'privkey': self._gpg.export_keys(self._fingerprint, secret=True), 'symkey': self._symkey, }) if passphrase: data = str(self._gpg.encrypt(data, None, sign=None, passphrase=passphrase, symmetric=True)) return data def import_recovery_document(self, data, passphrase): if self._has_keys(): raise KeyAlreadyExists("You tried to import a recovery document " "but secret keys are already present.") if passphrase and not self._gpg.is_encrypted_sym(data): raise DocumentNotEncrypted("You provided a password but the " "recovery document is not encrypted.") if passphrase: data = str(self._gpg.decrypt(data, passphrase=passphrase)) data = json.loads(data) self._user_email = data['user_email'] self._gpg.import_keys(data['privkey']) self._load_privkey() self._symkey = data['symkey'] self._store_symkey() # TODO: make this work well with bootstrap. self._load_keys() __all__ = ['backends', 'util', 'server', 'shared_db']