-t">Types.Session.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>encrypt_message_length sess plaintext_len</code></p><p>The size of the next message in bytes for the given number of plain-text bytes</p></dd></dl><dl><dt class="spec value" id="val-encrypt"><a href="#val-encrypt" class="anchor"></a><code><span class="keyword">val</span> encrypt : <span><a href="../Types/Session/index.html#type-t">Types.Session.t</a> Ctypes_s