Outbound group session support in the python wrappers

python/.gitignore

 *.pyc
 /*.account
 /*.session
+/*.group_session

python/olm/__init__.py

 from .account import Account
 from .session import Session
+from .outbound_group_session import OutboundGroupSession

python/olm/__main__.py

@@ -8,7 +8,7 @@ import yaml
 
 from . import *
 
-if __name__ == '__main__':
+def build_arg_parser():
     parser = argparse.ArgumentParser()
     parser.add_argument("--key", help="Account encryption key", default="")
     commands = parser.add_subparsers()
@@ -206,5 +206,41 @@ if __name__ == '__main__':
 
     decrypt.set_defaults(func=do_decrypt)
 
+    outbound_group = commands.add_parser("outbound_group", help="Create an outbound group session")
+    outbound_group.add_argument("session_file", help="Local group session file")
+    outbound_group.set_defaults(func=do_outbound_group)
+
+    group_encrypt = commands.add_parser("group_encrypt", help="Encrypt a group message")
+    group_encrypt.add_argument("session_file", help="Local group session file")
+    group_encrypt.add_argument("plaintext_file", help="Plaintext",
+                               type=argparse.FileType('rb'), default=sys.stdin)
+    group_encrypt.add_argument("message_file", help="Message",
+                               type=argparse.FileType('wb'), default=sys.stdout)
+    group_encrypt.set_defaults(func=do_group_encrypt)
+
+    return parser
+
+def do_outbound_group(args):
+    if os.path.exists(args.session_file):
+        sys.stderr.write("Session %r file already exists" % (
+            args.session_file,
+        ))
+        sys.exit(1)
+    session = OutboundGroupSession()
+    with open(args.session_file, "wb") as f:
+            f.write(session.pickle(args.key))
+
+def do_group_encrypt(args):
+    session = OutboundGroupSession()
+    with open(args.session_file, "rb") as f:
+        session.unpickle(args.key, f.read())
+    plaintext = args.plaintext_file.read()
+    message = session.encrypt(plaintext)
+    with open(args.session_file, "wb") as f:
+        f.write(session.pickle(args.key))
+    args.message_file.write(message)
+
+if __name__ == '__main__':
+    parser = build_arg_parser()
     args = parser.parse_args()
     args.func(args)

python/olm/outbound_group_session.py

+import json
+
+from ._base import *
+
+lib.olm_outbound_group_session_size.argtypes = []
+lib.olm_outbound_group_session_size.restype = c_size_t
+
+lib.olm_outbound_group_session.argtypes = [c_void_p]
+lib.olm_outbound_group_session.restype = c_void_p
+
+lib.olm_outbound_group_session_last_error.argtypes = [c_void_p]
+lib.olm_outbound_group_session_last_error.restype = c_char_p
+
+def outbound_group_session_errcheck(res, func, args):
+    if res == ERR:
+        raise OlmError("%s: %s" % (
+            func.__name__, lib.olm_outbound_group_session_last_error(args[0])
+        ))
+    return res
+
+
+def outbound_group_session_function(func, *types):
+    func.argtypes = (c_void_p,) + types
+    func.restypes = c_size_t
+    func.errcheck = outbound_group_session_errcheck
+
+
+outbound_group_session_function(
+    lib.olm_pickle_outbound_group_session, c_void_p, c_size_t, c_void_p, c_size_t
+)
+outbound_group_session_function(
+    lib.olm_unpickle_outbound_group_session, c_void_p, c_size_t, c_void_p, c_size_t
+)
+
+outbound_group_session_function(lib.olm_init_outbound_group_session_random_length)
+outbound_group_session_function(lib.olm_init_outbound_group_session, c_void_p, c_size_t)
+outbound_group_session_function(lib.olm_group_encrypt_message_length, c_size_t)
+outbound_group_session_function(lib.olm_group_encrypt,
+    c_void_p, c_size_t,  # Plaintext
+    c_void_p, c_size_t,  # Message
+)
+
+
+class OutboundGroupSession(object):
+    def __init__(self):
+        self.buf = create_string_buffer(lib.olm_outbound_group_session_size())
+        self.ptr = lib.olm_outbound_group_session(self.buf)
+
+        random_length = lib.olm_init_outbound_group_session_random_length(self.ptr)
+        random = read_random(random_length)
+        random_buffer = create_string_buffer(random)
+        lib.olm_init_outbound_group_session(self.ptr, random_buffer, random_length)
+
+    def pickle(self, key):
+        key_buffer = create_string_buffer(key)
+        pickle_length = lib.olm_pickle_outbound_group_session_length(self.ptr)
+        pickle_buffer = create_string_buffer(pickle_length)
+        lib.olm_pickle_outbound_group_session(
+            self.ptr, key_buffer, len(key), pickle_buffer, pickle_length
+        )
+        return pickle_buffer.raw
+
+    def unpickle(self, key, pickle):
+        key_buffer = create_string_buffer(key)
+        pickle_buffer = create_string_buffer(pickle)
+        lib.olm_unpickle_outbound_group_session(
+            self.ptr, key_buffer, len(key), pickle_buffer, len(pickle)
+        )
+
+    def encrypt(self, plaintext):
+        message_length = lib.olm_group_encrypt_message_length(
+            self.ptr, len(plaintext)
+        )
+        message_buffer = create_string_buffer(message_length)
+
+        plaintext_buffer = create_string_buffer(plaintext)
+
+        lib.olm_group_encrypt(
+            self.ptr,
+            plaintext_buffer, len(plaintext),
+            message_buffer, message_length,
+        )
+        return message_buffer.raw

python/test_olm.sh

@@ -4,11 +4,13 @@ OLM="python -m olm"
 
 ALICE_ACCOUNT=alice.account
 ALICE_SESSION=alice.session
+ALICE_GROUP_SESSION=alice.group_session
 BOB_ACCOUNT=bob.account
 BOB_SESSION=bob.session
 
 rm $ALICE_ACCOUNT $BOB_ACCOUNT
 rm $ALICE_SESSION $BOB_SESSION
+rm $ALICE_GROUP_SESSION
 
 $OLM create_account $ALICE_ACCOUNT
 $OLM create_account $BOB_ACCOUNT
@@ -20,3 +22,9 @@ BOB_ONE_TIME_KEY="$($OLM keys --json $BOB_ACCOUNT | jq -r '.one_time_keys.curve2
 $OLM outbound $ALICE_ACCOUNT $ALICE_SESSION "$BOB_IDENTITY_KEY" "$BOB_ONE_TIME_KEY"
 
 echo "Hello world" | $OLM encrypt $ALICE_SESSION - - | $OLM inbound $BOB_ACCOUNT $BOB_SESSION - -
+
+
+### group sessions
+
+$OLM outbound_group $ALICE_GROUP_SESSION
+echo "Hello world" | $OLM group_encrypt $ALICE_GROUP_SESSION - -