Support ChaCha20+Poly1305 cipher suites.

nss/lib/freebl/poly1305/poly1305.h

+/*
+ * poly1305.h - header file for Poly1305 implementation.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef FREEBL_POLY1305_H_
+#define FREEBL_POLY1305_H_
+
+typedef unsigned char poly1305_state[512];
+
+/* Poly1305Init sets up |state| so that it can be used to calculate an
+ * authentication tag with the one-time key |key|. Note that |key| is a
+ * one-time key and therefore there is no `reset' method because that would
+ * enable several messages to be authenticated with the same key. */
+extern void Poly1305Init(poly1305_state* state,
+                         const unsigned char key[32]);
+
+/* Poly1305Update processes |in_len| bytes from |in|. It can be called zero or
+ * more times after poly1305_init. */
+extern void Poly1305Update(poly1305_state* state,
+                           const unsigned char *in,
+                           size_t inLen);
+
+/* Poly1305Finish completes the poly1305 calculation and writes a 16 byte
+ * authentication tag to |mac|. */
+extern void Poly1305Finish(poly1305_state* state,
+                           unsigned char mac[16]);
+
+#endif  /* FREEBL_POLY1305_H_ */