Add encryption_scheme property to LeapDocument.

3 files changed, 98 insertions, 24 deletions

diff --git a/src/leap/soledad/backends/couch.py b/src/leap/soledad/backends/couch.py
index 6440232d..13b6733c 100644
--- a/src/leap/soledad/backends/couch.py
+++ b/src/leap/soledad/backends/couch.py
@@ -35,6 +35,8 @@ from u1db.remote.server_state import ServerState
 from u1db.errors import DatabaseDoesNotExist
 from couchdb.client import Server, Document as CouchDocument
 from couchdb.http import ResourceNotFound
+
+
 from leap.soledad.backends.objectstore import (
     ObjectStoreDatabase,
     ObjectStoreSyncTarget,
@@ -142,7 +144,8 @@ class CouchDatabase(ObjectStoreDatabase):
         doc = self._factory(
             doc_id=doc_id,
             rev=cdoc['u1db_rev'],
-            has_conflicts=has_conflicts)
+            has_conflicts=has_conflicts,
+            encryption_scheme=cdoc['encryption_scheme'])
         contents = self._database.get_attachment(cdoc, 'u1db_json')
         if contents:
             doc.content = json.loads(contents.read())
@@ -192,12 +195,14 @@ class CouchDatabase(ObjectStoreDatabase):
         # prepare couch's Document
         cdoc = CouchDocument()
         cdoc['_id'] = doc.doc_id
-        # we have to guarantee that couch's _rev is cosistent
+        # we have to guarantee that couch's _rev is consistent
         old_cdoc = self._database.get(doc.doc_id)
         if old_cdoc is not None:
             cdoc['_rev'] = old_cdoc['_rev']
         # store u1db's rev
         cdoc['u1db_rev'] = doc.rev
+        # store document's encryption scheme
+        cdoc['encryption_scheme'] = doc.encryption_scheme
         # save doc in db
         self._database.save(cdoc)
         # store u1db's content as json string
diff --git a/src/leap/soledad/backends/leap_backend.py b/src/leap/soledad/backends/leap_backend.py
index 687b59ef..dfec9e85 100644
--- a/src/leap/soledad/backends/leap_backend.py
+++ b/src/leap/soledad/backends/leap_backend.py
@@ -56,6 +56,16 @@ class DocumentNotEncrypted(Exception):
     pass
 
 
+class EncryptionSchemes(object):
+    """
+    Representation of encryption schemes used to encrypt documents.
+    """
+
+    NONE = 'none'
+    SYMKEY = 'symkey'
+    PUBKEY = 'pubkey'
+
+
 class LeapDocument(Document):
     """
     Encryptable and syncable document.
@@ -69,7 +79,8 @@ class LeapDocument(Document):
     """
 
     def __init__(self, doc_id=None, rev=None, json='{}', has_conflicts=False,
-                 encrypted_json=None, crypto=None, syncable=True):
+                 encrypted_json=None, crypto=None, syncable=True,
+                 encryption_scheme=EncryptionSchemes.NONE):
         """
         Container for handling an encryptable document.
 
@@ -89,10 +100,14 @@ class LeapDocument(Document):
         @type crypto: soledad.Soledad
         @param syncable: Should this document be synced with remote replicas?
         @type syncable: bool
+        @param encryption_scheme: The encryption scheme for this objects'
+            contents.
+        @type encryption_scheme: str
         """
         Document.__init__(self, doc_id, rev, json, has_conflicts)
         self._crypto = crypto
         self._syncable = syncable
+        self._encryption_scheme = encryption_scheme
         if encrypted_json:
             self.set_encrypted_json(encrypted_json)
 
@@ -118,6 +133,7 @@ class LeapDocument(Document):
             cyphertext,
             self._crypto._hash_passphrase(self.doc_id))
         self.set_json(plaintext)
+        self.encryption_scheme = EncryptionSchemes.NONE
 
     def get_encrypted_json(self):
         """
@@ -163,6 +179,31 @@ class LeapDocument(Document):
         doc="Determine if document should be synced with server."
     )
 
+    def _get_encryption_scheme(self):
+        """
+        Return the encryption scheme used to encrypt this document's contents.
+
+        @return: The encryption scheme used to encrypt this document's
+            contents.
+        @rtype: str
+        """
+        return self._encryption_scheme
+
+    def _set_encryption_scheme(self, encryption_scheme=True):
+        """
+        Set the encryption scheme used to encrypt this document's contents.
+
+        @param encryption_scheme: The encryption scheme.
+        @type encryption_scheme: str
+        """
+        self._encryption_scheme = encryption_scheme
+
+    encryption_scheme = property(
+        _get_encryption_scheme,
+        _set_encryption_scheme,
+        doc="The encryption scheme used to encrypt this document's contents."
+    )
+
     def _get_rev(self):
         """
         Get the document revision.
@@ -249,13 +290,31 @@ class LeapSyncTarget(HTTPSyncTarget):
                 # decrypt after receiving from server.
                 if not self._crypto:
                     raise NoSoledadCryptoInstance()
+                # all content arriving should be encrypted either with the
+                # user's symmetric key or with the user's public key.
                 enc_json = json.loads(entry['content'])['_encrypted_json']
-                if not self._crypto.is_encrypted_sym(enc_json):
+                plain_json = None
+                if entry['encryption_scheme'] == EncryptionScheme.SYMKEY:
+                    if not self._crypto.is_encrypted_sym(enc_json):
+                        raise DocumentNotEncrypted(
+                            'Incoming document\'s contents should be '
+                            'encrypted with a symmetric key.')
+                    plain_json = self._crypto.decrypt_symmetric(
+                        enc_json, self._crypto._symkey)
+                elif entry['encryption_scheme'] == EncryptionScheme.PUBKEY:
+                    if not self._crypto.is_encrypted_asym(enc_json):
+                        raise DocumentNotEncrypted(
+                            'Incoming document\'s contents should be '
+                            'encrypted to the user\'s public key.')
+                    plain_json = self._crypto.decrypt(enc_json)
+                else:
                     raise DocumentNotEncrypted(
                         "Incoming document from sync is not encrypted.")
+                # if decryption was OK, then create the document.
                 doc = LeapDocument(entry['id'], entry['rev'],
-                                   encrypted_json=entry['content'],
-                                   crypto=self._crypto)
+                                   json=plain_json,
+                                   crypto=self._crypto,
+                                   encryption_scheme=EncryptionScheme.NONE)
                 return_doc_cb(doc, entry['gen'], entry['trans_id'])
         if parts[-1] != ']':
             try:
@@ -307,8 +366,9 @@ class LeapSyncTarget(HTTPSyncTarget):
                     raise DocumentNotEncrypted(
                         "Could not encrypt document before sync.")
                 size += prepare(id=doc.doc_id, rev=doc.rev,
-                                content=doc.get_encrypted_json(),
-                                gen=gen, trans_id=trans_id)
+                                content=enc_json,
+                                gen=gen, trans_id=trans_id,
+                                encryption_scheme=EncryptionSchemes.SYMKEY)
         entries.append('\r\n]')
         size += len(entries[-1])
         self._conn.putheader('content-length', str(size))
diff --git a/src/leap/soledad/backends/sqlcipher.py b/src/leap/soledad/backends/sqlcipher.py
index 288680d4..fb5c3e79 100644
--- a/src/leap/soledad/backends/sqlcipher.py
+++ b/src/leap/soledad/backends/sqlcipher.py
@@ -19,23 +19,22 @@
 """A U1DB backend that uses SQLCipher as its persistence layer."""
 
 import os
-from pysqlcipher import dbapi2
 import time
 
-# TODO: uncomment imports below after solving circular dependency issue
-# between leap_client and soledad.
-#from leap import util
-from u1db.backends import sqlite_backend
-#util.logger.debug(
-#    "Monkey-patching u1db.backends.sqlite_backend with pysqlcipher.dbapi2..."
-#)
-sqlite_backend.dbapi2 = dbapi2
 
+from u1db.backends import sqlite_backend
+from pysqlcipher import dbapi2
 from u1db import (
     errors,
 )
+from leap.soledad.backends.leap_backend import (
+    LeapDocument,
+    EncryptionSchemes,
+)
+
 
-from leap.soledad.backends.leap_backend import LeapDocument
+# Monkey-patch u1db.backends.sqlite_backend with pysqlcipher.dbapi2
+sqlite_backend.dbapi2 = dbapi2
 
 
 def open(path, password, create=True, document_factory=None, crypto=None):
@@ -101,12 +100,14 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase):
         self._crypto = crypto
 
         def factory(doc_id=None, rev=None, json='{}', has_conflicts=False,
-                    encrypted_json=None, syncable=True):
+                    encrypted_json=None, syncable=True,
+                    encryption_scheme=EncryptionSchemes.NONE):
             return LeapDocument(doc_id=doc_id, rev=rev, json=json,
                                 has_conflicts=has_conflicts,
                                 encrypted_json=encrypted_json,
+                                crypto=self._crypto,
                                 syncable=syncable,
-                                crypto=self._crypto)
+                                encryption_scheme=encryption_scheme)
         self.set_document_factory(factory)
 
     def _check_if_db_is_encrypted(self, sqlcipher_file):
@@ -247,6 +248,10 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase):
         c.execute(
             'ALTER TABLE document '
             'ADD COLUMN syncable BOOL NOT NULL DEFAULT TRUE')
+        c.execute(
+            'ALTER TABLE document '
+            'ADD COLUMN encryption_scheme TEXT NOT NULL DEFAULT \'%s\'' %
+            EncryptionSchemes.NONE)
 
     def _put_and_update_indexes(self, old_doc, doc):
         """
@@ -260,8 +265,9 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase):
         sqlite_backend.SQLitePartialExpandDatabase._put_and_update_indexes(
             self, old_doc, doc)
         c = self._db_handle.cursor()
-        c.execute('UPDATE document SET syncable=? WHERE doc_id=?',
-                  (doc.syncable, doc.doc_id))
+        c.execute('UPDATE document SET syncable=?, encryption_scheme=? '
+                  'WHERE doc_id=?',
+                  (doc.syncable, doc.encryption_scheme, doc.doc_id))
 
     def _get_doc(self, doc_id, check_for_conflicts=False):
         """
@@ -281,9 +287,12 @@ class SQLCipherDatabase(sqlite_backend.SQLitePartialExpandDatabase):
             self, doc_id, check_for_conflicts)
         if doc:
             c = self._db_handle.cursor()
-            c.execute('SELECT syncable FROM document WHERE doc_id=?',
+            c.execute('SELECT syncable, encryption_scheme FROM document '
+                      'WHERE doc_id=?',
                       (doc.doc_id,))
-            doc.syncable = bool(c.fetchone()[0])
+            result = c.fetchone()
+            doc.syncable = bool(result[0])
+            doc.encryption_scheme = result[1]
         return doc
 
 sqlite_backend.SQLiteDatabase.register_implementation(SQLCipherDatabase)