Comment on the encoding of the message counter.

2 files changed, 8 insertions, 8 deletions

diff --git a/src/inbound_group_session.c b/src/inbound_group_session.c
index f2a310a..82ff66f 100644
--- a/src/inbound_group_session.c
+++ b/src/inbound_group_session.c
@@ -88,10 +88,10 @@ static size_t _init_group_session_keys(
     }
 
     uint32_t counter = 0;
-    counter <<= 8; counter |= *ptr++;
-    counter <<= 8; counter |= *ptr++;
-    counter <<= 8; counter |= *ptr++;
-    counter <<= 8; counter |= *ptr++;
+    // Decode counter as a big endian 32-bit number.
+    for (unsigned i = 0; i < 4; i++) {
+        counter <<= 8; counter |= *ptr++;
+    }
 
     megolm_init(&session->initial_ratchet, ptr, counter);
     megolm_init(&session->latest_ratchet, ptr, counter);
diff --git a/src/outbound_group_session.c b/src/outbound_group_session.c
index 7116547..8686993 100644
--- a/src/outbound_group_session.c
+++ b/src/outbound_group_session.c
@@ -337,10 +337,10 @@ size_t olm_outbound_group_session_key(
     *ptr++ = SESSION_KEY_VERSION;
 
     uint32_t counter = session->ratchet.counter;
-    *ptr++ = 0xFF & (counter >> 24); counter <<= 8;
-    *ptr++ = 0xFF & (counter >> 24); counter <<= 8;
-    *ptr++ = 0xFF & (counter >> 24); counter <<= 8;
-    *ptr++ = 0xFF & (counter >> 24); counter <<= 8;
+    // Encode counter as a big endian 32-bit number.
+    if (unsigned i = 0; i < 4; i++) {
+        *ptr++ = 0xFF & (counter >> 24); counter <<= 8;
+    }
 
     memcpy(ptr, megolm_get_data(&session->ratchet), MEGOLM_RATCHET_LENGTH);
     ptr += MEGOLM_RATCHET_LENGTH;