From 2fc83aa9aca1ce84b3c425a670cdf6a3a8886b34 Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <richard@matrix.org>
Date: Mon, 5 Sep 2016 19:49:36 +0100
Subject: Sign megolm messages

Add ed25519 keys to the inbound and outbound sessions, and use them to sign and
verify megolm messages.

We just stuff the ed25519 public key in alongside the megolm session key (and
add a version byte), to save adding more boilerplate to the JS/python/etc
layers.
---
 include/olm/error.h                 | 5 +++++
 include/olm/inbound_group_session.h | 2 +-
 include/olm/message.h               | 8 +++++---
 3 files changed, 11 insertions(+), 4 deletions(-)

(limited to 'include')

diff --git a/include/olm/error.h b/include/olm/error.h
index 1c44de8..9d44a94 100644
--- a/include/olm/error.h
+++ b/include/olm/error.h
@@ -46,6 +46,11 @@ enum OlmErrorCode {
      */
     OLM_BAD_LEGACY_ACCOUNT_PICKLE = 13,
 
+    /**
+     * Received message had a bad signature
+     */
+    OLM_BAD_SIGNATURE = 14,
+
     /* remember to update the list of string constants in error.c when updating
      * this list. */
 };
diff --git a/include/olm/inbound_group_session.h b/include/olm/inbound_group_session.h
index e24f377..49992b2 100644
--- a/include/olm/inbound_group_session.h
+++ b/include/olm/inbound_group_session.h
@@ -97,7 +97,7 @@ size_t olm_init_inbound_group_session(
     OlmInboundGroupSession *session,
     uint32_t message_index,
 
-    /* base64-encoded key */
+    /* base64-encoded keys */
     uint8_t const * session_key, size_t session_key_length
 );
 
diff --git a/include/olm/message.h b/include/olm/message.h
index 5eb504d..61012c9 100644
--- a/include/olm/message.h
+++ b/include/olm/message.h
@@ -37,7 +37,8 @@ extern "C" {
 size_t _olm_encode_group_message_length(
     uint32_t chain_index,
     size_t ciphertext_length,
-    size_t mac_length
+    size_t mac_length,
+    size_t signature_length
 );
 
 /**
@@ -49,7 +50,8 @@ size_t _olm_encode_group_message_length(
  * output:             where to write the output. Should be at least
  *                     olm_encode_group_message_length() bytes long.
  * ciphertext_ptr:     returns the address that the ciphertext
- *                     should be written to, followed by the MAC.
+ *                     should be written to, followed by the MAC and the
+ *                     signature.
  *
  * Returns the size of the message, up to the MAC.
  */
@@ -76,7 +78,7 @@ struct _OlmDecodeGroupMessageResults {
  */
 void _olm_decode_group_message(
     const uint8_t *input, size_t input_length,
-    size_t mac_length,
+    size_t mac_length, size_t signature_length,
 
     /* output structure: updated with results */
     struct _OlmDecodeGroupMessageResults *results
-- 
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