Add Poly1305 authenticator algorithm (RFC 7539)

Test vectors are included from RFC 7539.

Poly1305 is also added to the benchmark program.
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 4c8fc3c..7d0960a 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -283,6 +283,7 @@
 //#define MBEDTLS_MD2_ALT
 //#define MBEDTLS_MD4_ALT
 //#define MBEDTLS_MD5_ALT
+//#define MBEDTLS_POLY1305_ALT
 //#define MBEDTLS_RIPEMD160_ALT
 //#define MBEDTLS_RSA_ALT
 //#define MBEDTLS_SHA1_ALT
@@ -2399,6 +2400,15 @@
 #define MBEDTLS_PLATFORM_C
 
 /**
+ * \def MBEDTLS_POLY1305_C
+ *
+ * Enable the Poly1305 MAC algorithm.
+ *
+ * Module:  library/poly1305.c
+ */
+#define MBEDTLS_POLY1305_C
+
+/**
  * \def MBEDTLS_RIPEMD160_C
  *
  * Enable the RIPEMD-160 hash algorithm.
diff --git a/include/mbedtls/error.h b/include/mbedtls/error.h
index ace0c47..feeda79 100644
--- a/include/mbedtls/error.h
+++ b/include/mbedtls/error.h
@@ -77,6 +77,7 @@
  * SHA256    1                  0x0037-0x0037
  * SHA512    1                  0x0039-0x0039
  * CHACHA20  1                  0x003B-0x003B
+ * POLY1305  1                  0x0041-0x0041
  *
  * High-level module nr (3 bits - 0x0...-0x7...)
  * Name      ID  Nr of Errors
diff --git a/include/mbedtls/poly1305.h b/include/mbedtls/poly1305.h
new file mode 100644
index 0000000..1aa55ae
--- /dev/null
+++ b/include/mbedtls/poly1305.h
@@ -0,0 +1,142 @@
+/**
+ * \file poly1305.h
+ *
+ * \brief Poly1305 authenticator algorithm.
+ *
+ *  Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ */
+#ifndef MBEDTLS_POLY1305_H
+#define MBEDTLS_POLY1305_H
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#include <stdint.h>
+#include <stddef.h>
+
+#if !defined(MBEDTLS_POLY1305_ALT)
+
+#define MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA -0x0041 /**< Invalid input parameter(s). */
+
+typedef struct
+{
+    uint32_t r[4];      /** Stores the value for 'r' (low 128 bits of the key) */
+    uint32_t s[4];      /** Stores the value for 's' (high 128 bits of the key) */
+    uint32_t acc[5];    /** Accumulator number */
+    uint8_t queue[16];  /** Stores partial block data */
+    size_t queue_len;   /** Number of bytes stored in 'queue'. Always less than 16 */
+}
+mbedtls_poly1305_context;
+
+/**
+ * \brief               Initialize a Poly1305 context
+ *
+ * \param ctx           The Poly1305 context to be initialized
+ */
+void mbedtls_poly1305_init( mbedtls_poly1305_context *ctx );
+
+/**
+ * \brief               Clear a Poly1305 context
+ *
+ * \param ctx           The Poly1305 context to be cleared
+ */
+void mbedtls_poly1305_free( mbedtls_poly1305_context *ctx );
+
+/**
+ * \brief               Set the Poly1305 authentication key.
+ *
+ * \warning             The key should be unique, and \b MUST be
+ *                      unpredictable for each invocation of Poly1305.
+ *
+ * \param ctx           The Poly1305 context.
+ * \param key           Buffer containing the 256-bit key.
+ *
+ * \return              MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA is returned if ctx
+ *                      or key are NULL.
+ *                      Otherwise, 0 is returned to indicate success.
+ */
+int mbedtls_poly1305_setkey( mbedtls_poly1305_context *ctx,
+                             const unsigned char key[32] );
+
+/**
+ * \brief               Process data with Poly1305.
+ *
+ *                      This function can be called multiple times to process
+ *                      a stream of data.
+ *
+ * \param ctx           The Poly1305 context.
+ * \param ilen          The input length (in bytes). Any value is accepted.
+ * \param input         Buffer containing the input data to Process.
+ *
+ * \return              MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA is returned if ctx
+ *                      or input are NULL.
+ *                      Otherwise, 0 is returned to indicate success.
+ */
+int mbedtls_poly1305_update( mbedtls_poly1305_context *ctx,
+                             size_t ilen,
+                             const unsigned char *input );
+
+/**
+ * \brief               Generate the Poly1305 MAC.
+ *
+ * \param ctx           The Poly1305 context.
+ * \param mac           Buffer to where the MAC is written. Must be big enough
+ *                      to hold the 16-byte MAC.
+ *
+ * \return              MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA is returned if ctx
+ *                      or mac are NULL.
+ *                      Otherwise, 0 is returned to indicate success.
+ */
+int mbedtls_poly1305_finish( mbedtls_poly1305_context *ctx,
+                             unsigned char mac[16] );
+
+#else  /* MBEDTLS_POLY1305_ALT */
+#include "poly1305_alt.h"
+#endif /* MBEDTLS_POLY1305_ALT */
+
+/**
+ * \brief               Generate the Poly1305 MAC of some data with the given key.
+ *
+ * \warning             The key should be unique, and \b MUST be
+ *                      unpredictable for each invocation of Poly1305.
+ *
+ * \param key           Buffer containing the 256-bit (32 bytes) key.
+ * \param ilen          The length of the input data (in bytes).
+ * \param input         Buffer containing the input data to process.
+ * \param mac           Buffer to where the 128-bit (16 bytes) MAC is written.
+ *
+ * \return              MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA is returned if key,
+ *                      input, or mac are NULL.
+ *                      Otherwise, 0 is returned to indicate success.
+ */
+int mbedtls_poly1305_mac( const unsigned char key[32],
+                          size_t ilen,
+                          const unsigned char *input,
+                          unsigned char mac[16] );
+
+/**
+ * \brief               Checkup routine
+ *
+ * \return              0 if successful, or 1 if the test failed
+ */
+int mbedtls_poly1305_self_test( int verbose );
+
+#endif /* MBEDTLS_POLY1305_H */