value" id="val-inbound_group_session_first_known_index"><a href="#val-inbound_group_session_first_known_index" class="anchor"></a><code><span class="keyword">val</span> inbound_group_session_first_known_index : <span><a href="../Types/InboundGroupSession/index.html#type-t">Types.InboundGroupSession.t</a> Ctypes_static.ptr</span> <span>&#45;&gt;</span> Unsigned.uint32</code></dt><dd><p><code>inbound_group_session_first_known_index sess</code></p><p>Get the first message index we know how to decrypt.</p></dd>