h : <span><a href="../Types/OutboundGroupSession/index.html#type-t">Types.OutboundGroupSession.t</a> Ctypes_static.ptr</span> <span>&#45;&gt;</span> Unsigned.size_t <span>&#45;&gt;</span> Unsigned.size_t</code></dt><dd><p><code>group_encrypt_message_length sess plaintext_len</code></p><p>The number of bytes that will be created by encrypting a message</p></dd></dl><dl><dt class="spec value" id="val-group_encrypt"><a href="#val-group_encrypt" class="anchor"></a><code><span class="keyword">val</span> group_en