library/poly1305.c - security/mbedtls - Rivoreo Source Code Repositories

 /**
  * \file poly1305.c
  *
  * \brief Poly1305 authentication 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)
  */
 #if !defined(MBEDTLS_CONFIG_FILE)
 #include "mbedtls/config.h"
 #else
 #include MBEDTLS_CONFIG_FILE
 #endif

 #if defined(MBEDTLS_POLY1305_C)

 #if !defined(MBEDTLS_POLY1305_ALT)

 #include "mbedtls/poly1305.h"

 #include <string.h>

 #if defined(MBEDTLS_SELF_TEST)
 #if defined(MBEDTLS_PLATFORM_C)
 #include "mbedtls/platform.h"
 #else
 #include <stdio.h>
 #define mbedtls_printf printf
 #endif /* MBEDTLS_PLATFORM_C */
 #endif /* MBEDTLS_SELF_TEST */

 #define POLY1305_BLOCK_SIZE_BYTES ( 16U )

 #define BYTES_TO_U32_LE( data, offset )                   \
     ( (uint32_t)data[offset] |                            \
       (uint32_t)( (uint32_t)data[(offset) + 1] << 8 )  |  \
       (uint32_t)( (uint32_t)data[(offset) + 2] << 16 ) |  \
       (uint32_t)( (uint32_t)data[(offset) + 3] << 24 )    \
     )

 /* Implementation that should never be optimized out by the compiler */
 static void mbedtls_zeroize( void *v, size_t n ) {
     volatile unsigned char *p = v; while( n-- ) *p++ = 0;
 }

 /**
  * \brief                   Process blocks with Poly1305.
  *
  * \param ctx               The Poly1305 context.
  * \param nblocks           Number of blocks to process. Note that this function
  *                          only processes full blocks.
  * \param input             Buffer containing the input block(s).
  * \param needs_padding     Set to 0 if the padding bit has already been applied
  *                          to the input data before calling this function.
  *                          Otherwise, set this parameter to 1.
  */
 static void mbedtls_poly1305_process( mbedtls_poly1305_context *ctx,
                                       size_t nblocks,
                                       const unsigned char *input,
                                       uint32_t needs_padding )
 {
     uint64_t d0, d1, d2, d3;
     uint32_t acc0, acc1, acc2, acc3, acc4;
     uint32_t r0, r1, r2, r3;
     uint32_t rs1, rs2, rs3;
     size_t offset  = 0U;
     size_t i;

     r0 = ctx->r[0];
     r1 = ctx->r[1];
     r2 = ctx->r[2];
     r3 = ctx->r[3];

     rs1 = r1 + ( r1 >> 2U );
     rs2 = r2 + ( r2 >> 2U );
     rs3 = r3 + ( r3 >> 2U );

     acc0 = ctx->acc[0];
     acc1 = ctx->acc[1];
     acc2 = ctx->acc[2];
     acc3 = ctx->acc[3];
     acc4 = ctx->acc[4];

     /* Process full blocks */
     for ( i = 0U; i < nblocks; i++ )
     {
         /* Compute: acc += block */
         /* Note that the input block is treated as a 128-bit little-endian integer */
         d0   = (uint64_t)acc0 + BYTES_TO_U32_LE( input, offset + 0  );
         d1   = (uint64_t)acc1 + BYTES_TO_U32_LE( input, offset + 4  ) + ( d0 >> 32U );
         d2   = (uint64_t)acc2 + BYTES_TO_U32_LE( input, offset + 8  ) + ( d1 >> 32U );
         d3   = (uint64_t)acc3 + BYTES_TO_U32_LE( input, offset + 12 ) + ( d2 >> 32U );
         acc0 = (uint32_t)d0;
         acc1 = (uint32_t)d1;
         acc2 = (uint32_t)d2;
         acc3 = (uint32_t)d3;
         acc4 += (uint32_t)( d3 >> 32U ) + needs_padding;

         /* Compute: acc *= r */
         d0 = ( (uint64_t)acc0 * r0  ) +
              ( (uint64_t)acc1 * rs3 ) +
              ( (uint64_t)acc2 * rs2 ) +
              ( (uint64_t)acc3 * rs1 );
         d1 = ( (uint64_t)acc0 * r1  ) +
              ( (uint64_t)acc1 * r0  ) +
              ( (uint64_t)acc2 * rs3 ) +
              ( (uint64_t)acc3 * rs2 ) +
              ( (uint64_t)acc4 * rs1 );
         d2 = ( (uint64_t)acc0 * r2  ) +
              ( (uint64_t)acc1 * r1  ) +
              ( (uint64_t)acc2 * r0  ) +
              ( (uint64_t)acc3 * rs3 ) +
              ( (uint64_t)acc4 * rs2 );
         d3 = ( (uint64_t)acc0 * r3  ) +
              ( (uint64_t)acc1 * r2  ) +
              ( (uint64_t)acc2 * r1  ) +
              ( (uint64_t)acc3 * r0  ) +
              ( (uint64_t)acc4 * rs3 );
         acc4 *= r0;

         /* Compute: acc %= (2^130 - 5) (partial remainder) */
         d1 += ( d0 >> 32 );
         d2 += ( d1 >> 32 );
         d3 += ( d2 >> 32 );
         acc0 = (uint32_t)d0;
         acc1 = (uint32_t)d1;
         acc2 = (uint32_t)d2;
         acc3 = (uint32_t)d3;
         acc4 = (uint32_t)( d3 >> 32 ) + acc4;

         d0 = (uint64_t)acc0 + ( acc4 >> 2 ) + ( acc4 & 0xFFFFFFFCU );
         acc4 &= 3U;
         acc0 = (uint32_t)d0;
         d0 = (uint64_t)acc1 + ( d0 >> 32U );
         acc1 = (uint32_t)d0;
         d0 = (uint64_t)acc2 + ( d0 >> 32U );
         acc2 = (uint32_t)d0;
         d0 = (uint64_t)acc3 + ( d0 >> 32U );
         acc3 = (uint32_t)d0;
         d0 = (uint64_t)acc4 + ( d0 >> 32U );
         acc4 = (uint32_t)d0;

         offset    += POLY1305_BLOCK_SIZE_BYTES;
     }

     ctx->acc[0] = acc0;
     ctx->acc[1] = acc1;
     ctx->acc[2] = acc2;
     ctx->acc[3] = acc3;
     ctx->acc[4] = acc4;
 }

 /**
  * \brief                   Compute the Poly1305 MAC
  *
  * \param ctx               The Poly1305 context.
  * \param mac               The buffer to where the MAC is written. Must be
  *                          big enough to contain the 16-byte MAC.
  */
 static void mbedtls_poly1305_compute_mac( const mbedtls_poly1305_context *ctx,
                                           unsigned char mac[16] )
 {
     uint64_t d;
     uint32_t g0, g1, g2, g3, g4;
     uint32_t acc0, acc1, acc2, acc3, acc4;
     uint32_t mask;
     uint32_t mask_inv;

     acc0 = ctx->acc[0];
     acc1 = ctx->acc[1];
     acc2 = ctx->acc[2];
     acc3 = ctx->acc[3];
     acc4 = ctx->acc[4];

     /* Before adding 's' we need to ensure that the accumulator is mod 2^130 - 5.
      * We do this by calculating acc - (2^130 - 5), then checking if
      * the 131st bit is set. If it is, then reduce: acc -= (2^130 - 5)
      */

     /* Calculate acc + -(2^130 - 5) */
     d  = ( (uint64_t)acc0 + 5U );
     g0 = (uint32_t)d;
     d  = ( (uint64_t)acc1 + ( d >> 32 ) );
     g1 = (uint32_t)d;
     d  = ( (uint64_t)acc2 + ( d >> 32 ) );
     g2 = (uint32_t)d;
     d  = ( (uint64_t)acc3 + ( d >> 32 ) );
     g3 = (uint32_t)d;
     g4 = acc4 + (uint32_t)( d >> 32U );

     /* mask == 0xFFFFFFFF if 131st bit is set, otherwise mask == 0 */
     mask = (uint32_t)0U - ( g4 >> 2U );
     mask_inv = ~mask;

     /* If 131st bit is set then acc=g, otherwise, acc is unmodified */
     acc0 = ( acc0 & mask_inv ) | ( g0 & mask );
     acc1 = ( acc1 & mask_inv ) | ( g1 & mask );
     acc2 = ( acc2 & mask_inv ) | ( g2 & mask );
     acc3 = ( acc3 & mask_inv ) | ( g3 & mask );

     /* Add 's' */
     d = (uint64_t)acc0 + ctx->s[0];
     acc0 = (uint32_t)d;
     d = (uint64_t)acc1 + ctx->s[1] + ( d >> 32U );
     acc1 = (uint32_t)d;
     d = (uint64_t)acc2 + ctx->s[2] + ( d >> 32U );
     acc2 = (uint32_t)d;
     acc3 += ctx->s[3] + (uint32_t)( d >> 32U );

     /* Compute MAC (128 least significant bits of the accumulator) */
     mac[0]  = (uint8_t)acc0;
     mac[1]  = (uint8_t)( acc0 >> 8  );
     mac[2]  = (uint8_t)( acc0 >> 16 );
     mac[3]  = (uint8_t)( acc0 >> 24 );
     mac[4]  = (uint8_t)acc1;
     mac[5]  = (uint8_t)( acc1 >> 8  );
     mac[6]  = (uint8_t)( acc1 >> 16 );
     mac[7]  = (uint8_t)( acc1 >> 24 );
     mac[8]  = (uint8_t)acc2;
     mac[9]  = (uint8_t)( acc2 >> 8  );
     mac[10] = (uint8_t)( acc2 >> 16 );
     mac[11] = (uint8_t)( acc2 >> 24 );
     mac[12] = (uint8_t)acc3;
     mac[13] = (uint8_t)( acc3 >> 8  );
     mac[14] = (uint8_t)( acc3 >> 16 );
     mac[15] = (uint8_t)( acc3 >> 24 );
 }

 void mbedtls_poly1305_init( mbedtls_poly1305_context *ctx )
 {
     if ( ctx != NULL )
     {
         mbedtls_zeroize( ctx, sizeof(mbedtls_poly1305_context) );
     }
 }

 void mbedtls_poly1305_free( mbedtls_poly1305_context *ctx )
 {
     if ( ctx != NULL )
     {
         mbedtls_zeroize( ctx, sizeof(mbedtls_poly1305_context) );
     }
 }

 int mbedtls_poly1305_setkey( mbedtls_poly1305_context *ctx,
                              const unsigned char key[32] )
 {
     if ( ctx == NULL )
     {
         return( MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA );
     }

     /* r &= 0x0ffffffc0ffffffc0ffffffc0fffffff */
     ctx->r[0] = BYTES_TO_U32_LE( key, 0 )  & 0x0FFFFFFFU;
     ctx->r[1] = BYTES_TO_U32_LE( key, 4 )  & 0x0FFFFFFCU;
     ctx->r[2] = BYTES_TO_U32_LE( key, 8 )  & 0x0FFFFFFCU;
     ctx->r[3] = BYTES_TO_U32_LE( key, 12 ) & 0x0FFFFFFCU;

     ctx->s[0] = BYTES_TO_U32_LE( key, 16 );
     ctx->s[1] = BYTES_TO_U32_LE( key, 20 );
     ctx->s[2] = BYTES_TO_U32_LE( key, 24 );
     ctx->s[3] = BYTES_TO_U32_LE( key, 28 );

     /* Initial accumulator state */
     ctx->acc[0] = 0U;
     ctx->acc[1] = 0U;
     ctx->acc[2] = 0U;
     ctx->acc[3] = 0U;

     return 0;
 }

 int mbedtls_poly1305_update( mbedtls_poly1305_context *ctx,
                              size_t ilen,
                              const unsigned char* input )
 {
     size_t offset    = 0U;
     size_t remaining = ilen;
     size_t queue_free_len;
     size_t nblocks;

     if ( ( ctx == NULL ) || ( input == NULL ) )
     {
         return( MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA );
     }

     if ( ctx->queue_len > 0U )
     {
         queue_free_len = ( POLY1305_BLOCK_SIZE_BYTES - ctx->queue_len );

         if ( ilen < queue_free_len )
         {
             /* Not enough data to complete the block.
              * Store this data with the other leftovers.
              */
             memcpy( &ctx->queue[ctx->queue_len],
                     input,
                     ilen );

             ctx->queue_len += ilen;

             remaining = 0U;
         }
         else
         {
             /* Enough data to produce a complete block */
             memcpy( &ctx->queue[ctx->queue_len],
                     input,
                     queue_free_len );

             ctx->queue_len = 0U;

             mbedtls_poly1305_process( ctx,
                                       1U,
                                       ctx->queue,
                                       1U ); /* add padding bit */

             offset    += queue_free_len;
             remaining -= queue_free_len;
         }
     }

     if ( remaining >= POLY1305_BLOCK_SIZE_BYTES )
     {
         nblocks = remaining / POLY1305_BLOCK_SIZE_BYTES;

         mbedtls_poly1305_process( ctx, nblocks, &input[offset], 1U );

         offset += nblocks * POLY1305_BLOCK_SIZE_BYTES;
         remaining %= POLY1305_BLOCK_SIZE_BYTES;
     }

     if ( remaining > 0U )
     {
         /* Store partial block */
         ctx->queue_len = remaining;
         memcpy( ctx->queue, &input[offset], remaining );
     }

     return( 0 );
 }

 int mbedtls_poly1305_finish( mbedtls_poly1305_context *ctx,
                              unsigned char mac[16] )
 {
     if ( ( ctx == NULL ) || ( mac == NULL ) )
     {
         return( MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA );
     }

     /* Process any leftover data */
     if ( ctx->queue_len > 0U )
     {
         /* Add padding bit */
         ctx->queue[ctx->queue_len] = 1U;
         ctx->queue_len++;

         /* Pad with zeroes */
         memset( &ctx->queue[ctx->queue_len],
                 0,
                 POLY1305_BLOCK_SIZE_BYTES - ctx->queue_len );

         mbedtls_poly1305_process( ctx,
                                   1U,           /* Process 1 block */
                                   ctx->queue,
                                   0U );         /* Don't add padding bit (it was just added above) */
     }

     mbedtls_poly1305_compute_mac( ctx, mac );

     return( 0 );
 }

 #endif /* MBEDTLS_POLY1305_ALT */

 int mbedtls_poly1305_mac( const unsigned char key[32],
                            size_t ilen,
                            const unsigned char *input,
                            unsigned char mac[16] )
 {
     mbedtls_poly1305_context ctx;
     int result;

     mbedtls_poly1305_init( &ctx );

     result = mbedtls_poly1305_setkey( &ctx, key );
     if ( result != 0 )
         goto cleanup;

     result = mbedtls_poly1305_update( &ctx, ilen, input );
     if ( result != 0 )
         goto cleanup;

     result = mbedtls_poly1305_finish( &ctx, mac );

 cleanup:
     mbedtls_poly1305_free( &ctx );
     return( 0 );
 }

 #if defined(MBEDTLS_SELF_TEST)

 static const unsigned char test_keys[2][32] =
 {
     {
         0x85, 0xd6, 0xbe, 0x78, 0x57, 0x55, 0x6d, 0x33,
         0x7f, 0x44, 0x52, 0xfe, 0x42, 0xd5, 0x06, 0xa8,
         0x01, 0x03, 0x80, 0x8a, 0xfb, 0x0d, 0xb2, 0xfd,
         0x4a, 0xbf, 0xf6, 0xaf, 0x41, 0x49, 0xf5, 0x1b
     },
     {
         0x1c, 0x92, 0x40, 0xa5, 0xeb, 0x55, 0xd3, 0x8a,
         0xf3, 0x33, 0x88, 0x86, 0x04, 0xf6, 0xb5, 0xf0,
         0x47, 0x39, 0x17, 0xc1, 0x40, 0x2b, 0x80, 0x09,
         0x9d, 0xca, 0x5c, 0xbc, 0x20, 0x70, 0x75, 0xc0
     }
 };

 static const unsigned char test_data[2][127] =
 {
     {
         0x43, 0x72, 0x79, 0x70, 0x74, 0x6f, 0x67, 0x72,
         0x61, 0x70, 0x68, 0x69, 0x63, 0x20, 0x46, 0x6f,
         0x72, 0x75, 0x6d, 0x20, 0x52, 0x65, 0x73, 0x65,
         0x61, 0x72, 0x63, 0x68, 0x20, 0x47, 0x72, 0x6f,
         0x75, 0x70
     },
     {
         0x27, 0x54, 0x77, 0x61, 0x73, 0x20, 0x62, 0x72,
         0x69, 0x6c, 0x6c, 0x69, 0x67, 0x2c, 0x20, 0x61,
         0x6e, 0x64, 0x20, 0x74, 0x68, 0x65, 0x20, 0x73,
         0x6c, 0x69, 0x74, 0x68, 0x79, 0x20, 0x74, 0x6f,
         0x76, 0x65, 0x73, 0x0a, 0x44, 0x69, 0x64, 0x20,
         0x67, 0x79, 0x72, 0x65, 0x20, 0x61, 0x6e, 0x64,
         0x20, 0x67, 0x69, 0x6d, 0x62, 0x6c, 0x65, 0x20,
         0x69, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x77,
         0x61, 0x62, 0x65, 0x3a, 0x0a, 0x41, 0x6c, 0x6c,
         0x20, 0x6d, 0x69, 0x6d, 0x73, 0x79, 0x20, 0x77,
         0x65, 0x72, 0x65, 0x20, 0x74, 0x68, 0x65, 0x20,
         0x62, 0x6f, 0x72, 0x6f, 0x67, 0x6f, 0x76, 0x65,
         0x73, 0x2c, 0x0a, 0x41, 0x6e, 0x64, 0x20, 0x74,
         0x68, 0x65, 0x20, 0x6d, 0x6f, 0x6d, 0x65, 0x20,
         0x72, 0x61, 0x74, 0x68, 0x73, 0x20, 0x6f, 0x75,
         0x74, 0x67, 0x72, 0x61, 0x62, 0x65, 0x2e
     }
 };

 static const size_t test_data_len[2] =
 {
     34U,
     127U
 };

 static const unsigned char test_mac[2][16] =
 {
     {
         0xa8, 0x06, 0x1d, 0xc1, 0x30, 0x51, 0x36, 0xc6,
         0xc2, 0x2b, 0x8b, 0xaf, 0x0c, 0x01, 0x27, 0xa9
     },
     {
         0x45, 0x41, 0x66, 0x9a, 0x7e, 0xaa, 0xee, 0x61,
         0xe7, 0x08, 0xdc, 0x7c, 0xbc, 0xc5, 0xeb, 0x62
     }
 };

 int mbedtls_poly1305_self_test( int verbose )
 {
     uint8_t mac[16];
     size_t i;
     int result;

     for ( i = 0U; i < 2U; i++ )
     {
         result = mbedtls_poly1305_mac( test_keys[i],
                                         test_data_len[i],
                                         test_data[i],
                                         mac );
         if ( result != 0 )
         {
             if ( verbose != 0 )
             {
                 mbedtls_printf( "Poly1305 test %zi error code: %i\n", i, result );
             }

             return( -1 );
         }

         if ( memcmp( mac, test_mac[i], 16U ) != 0 )
         {
             if ( verbose != 0 )
             {
                 mbedtls_printf( "Poly1305 test %zi failed\n", i );
             }

             return( -1 );
         }
     }

     return( 0 );
 }

 #endif /* MBEDTLS_SELF_TEST */

 #endif /* MBEDTLS_POLY1305_C */
	/**
	* \file poly1305.c
	*
	* \brief Poly1305 authentication 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)
	*/
	#if !defined(MBEDTLS_CONFIG_FILE)
	#include "mbedtls/config.h"
	#else
	#include MBEDTLS_CONFIG_FILE
	#endif

	#if defined(MBEDTLS_POLY1305_C)

	#if !defined(MBEDTLS_POLY1305_ALT)

	#include "mbedtls/poly1305.h"

	#include <string.h>

	#if defined(MBEDTLS_SELF_TEST)
	#if defined(MBEDTLS_PLATFORM_C)
	#include "mbedtls/platform.h"
	#else
	#include <stdio.h>
	#define mbedtls_printf printf
	#endif /* MBEDTLS_PLATFORM_C */
	#endif /* MBEDTLS_SELF_TEST */

	#define POLY1305_BLOCK_SIZE_BYTES ( 16U )

	#define BYTES_TO_U32_LE( data, offset ) \
	( (uint32_t)data[offset] \| \
	(uint32_t)( (uint32_t)data[(offset) + 1] << 8 ) \| \
	(uint32_t)( (uint32_t)data[(offset) + 2] << 16 ) \| \
	(uint32_t)( (uint32_t)data[(offset) + 3] << 24 ) \
	)

	/* Implementation that should never be optimized out by the compiler */
	static void mbedtls_zeroize( void *v, size_t n ) {
	volatile unsigned char p = v; while( n-- ) p++ = 0;
	}

	/**
	* \brief Process blocks with Poly1305.
	*
	* \param ctx The Poly1305 context.
	* \param nblocks Number of blocks to process. Note that this function
	* only processes full blocks.
	* \param input Buffer containing the input block(s).
	* \param needs_padding Set to 0 if the padding bit has already been applied
	* to the input data before calling this function.
	* Otherwise, set this parameter to 1.
	*/
	static void mbedtls_poly1305_process( mbedtls_poly1305_context *ctx,
	size_t nblocks,
	const unsigned char *input,
	uint32_t needs_padding )
	{
	uint64_t d0, d1, d2, d3;
	uint32_t acc0, acc1, acc2, acc3, acc4;
	uint32_t r0, r1, r2, r3;
	uint32_t rs1, rs2, rs3;
	size_t offset = 0U;
	size_t i;

	r0 = ctx->r[0];
	r1 = ctx->r[1];
	r2 = ctx->r[2];
	r3 = ctx->r[3];

	rs1 = r1 + ( r1 >> 2U );
	rs2 = r2 + ( r2 >> 2U );
	rs3 = r3 + ( r3 >> 2U );

	acc0 = ctx->acc[0];
	acc1 = ctx->acc[1];
	acc2 = ctx->acc[2];
	acc3 = ctx->acc[3];
	acc4 = ctx->acc[4];

	/* Process full blocks */
	for ( i = 0U; i < nblocks; i++ )
	{
	/* Compute: acc += block */
	/* Note that the input block is treated as a 128-bit little-endian integer */
	d0 = (uint64_t)acc0 + BYTES_TO_U32_LE( input, offset + 0 );
	d1 = (uint64_t)acc1 + BYTES_TO_U32_LE( input, offset + 4 ) + ( d0 >> 32U );
	d2 = (uint64_t)acc2 + BYTES_TO_U32_LE( input, offset + 8 ) + ( d1 >> 32U );
	d3 = (uint64_t)acc3 + BYTES_TO_U32_LE( input, offset + 12 ) + ( d2 >> 32U );
	acc0 = (uint32_t)d0;
	acc1 = (uint32_t)d1;
	acc2 = (uint32_t)d2;
	acc3 = (uint32_t)d3;
	acc4 += (uint32_t)( d3 >> 32U ) + needs_padding;

	/* Compute: acc = r /
	d0 = ( (uint64_t)acc0 * r0 ) +
	( (uint64_t)acc1 * rs3 ) +
	( (uint64_t)acc2 * rs2 ) +
	( (uint64_t)acc3 * rs1 );
	d1 = ( (uint64_t)acc0 * r1 ) +
	( (uint64_t)acc1 * r0 ) +
	( (uint64_t)acc2 * rs3 ) +
	( (uint64_t)acc3 * rs2 ) +
	( (uint64_t)acc4 * rs1 );
	d2 = ( (uint64_t)acc0 * r2 ) +
	( (uint64_t)acc1 * r1 ) +
	( (uint64_t)acc2 * r0 ) +
	( (uint64_t)acc3 * rs3 ) +
	( (uint64_t)acc4 * rs2 );
	d3 = ( (uint64_t)acc0 * r3 ) +
	( (uint64_t)acc1 * r2 ) +
	( (uint64_t)acc2 * r1 ) +
	( (uint64_t)acc3 * r0 ) +
	( (uint64_t)acc4 * rs3 );
	acc4 *= r0;

	/* Compute: acc %= (2^130 - 5) (partial remainder) */
	d1 += ( d0 >> 32 );
	d2 += ( d1 >> 32 );
	d3 += ( d2 >> 32 );
	acc0 = (uint32_t)d0;
	acc1 = (uint32_t)d1;
	acc2 = (uint32_t)d2;
	acc3 = (uint32_t)d3;
	acc4 = (uint32_t)( d3 >> 32 ) + acc4;

	d0 = (uint64_t)acc0 + ( acc4 >> 2 ) + ( acc4 & 0xFFFFFFFCU );
	acc4 &= 3U;
	acc0 = (uint32_t)d0;
	d0 = (uint64_t)acc1 + ( d0 >> 32U );
	acc1 = (uint32_t)d0;
	d0 = (uint64_t)acc2 + ( d0 >> 32U );
	acc2 = (uint32_t)d0;
	d0 = (uint64_t)acc3 + ( d0 >> 32U );
	acc3 = (uint32_t)d0;
	d0 = (uint64_t)acc4 + ( d0 >> 32U );
	acc4 = (uint32_t)d0;

	offset += POLY1305_BLOCK_SIZE_BYTES;
	}

	ctx->acc[0] = acc0;
	ctx->acc[1] = acc1;
	ctx->acc[2] = acc2;
	ctx->acc[3] = acc3;
	ctx->acc[4] = acc4;
	}

	/**
	* \brief Compute the Poly1305 MAC
	*
	* \param ctx The Poly1305 context.
	* \param mac The buffer to where the MAC is written. Must be
	* big enough to contain the 16-byte MAC.
	*/
	static void mbedtls_poly1305_compute_mac( const mbedtls_poly1305_context *ctx,
	unsigned char mac[16] )
	{
	uint64_t d;
	uint32_t g0, g1, g2, g3, g4;
	uint32_t acc0, acc1, acc2, acc3, acc4;
	uint32_t mask;
	uint32_t mask_inv;

	acc0 = ctx->acc[0];
	acc1 = ctx->acc[1];
	acc2 = ctx->acc[2];
	acc3 = ctx->acc[3];
	acc4 = ctx->acc[4];

	/* Before adding 's' we need to ensure that the accumulator is mod 2^130 - 5.
	* We do this by calculating acc - (2^130 - 5), then checking if
	* the 131st bit is set. If it is, then reduce: acc -= (2^130 - 5)
	*/

	/* Calculate acc + -(2^130 - 5) */
	d = ( (uint64_t)acc0 + 5U );
	g0 = (uint32_t)d;
	d = ( (uint64_t)acc1 + ( d >> 32 ) );
	g1 = (uint32_t)d;
	d = ( (uint64_t)acc2 + ( d >> 32 ) );
	g2 = (uint32_t)d;
	d = ( (uint64_t)acc3 + ( d >> 32 ) );
	g3 = (uint32_t)d;
	g4 = acc4 + (uint32_t)( d >> 32U );

	/* mask == 0xFFFFFFFF if 131st bit is set, otherwise mask == 0 */
	mask = (uint32_t)0U - ( g4 >> 2U );
	mask_inv = ~mask;

	/* If 131st bit is set then acc=g, otherwise, acc is unmodified */
	acc0 = ( acc0 & mask_inv ) \| ( g0 & mask );
	acc1 = ( acc1 & mask_inv ) \| ( g1 & mask );
	acc2 = ( acc2 & mask_inv ) \| ( g2 & mask );
	acc3 = ( acc3 & mask_inv ) \| ( g3 & mask );

	/* Add 's' */
	d = (uint64_t)acc0 + ctx->s[0];
	acc0 = (uint32_t)d;
	d = (uint64_t)acc1 + ctx->s[1] + ( d >> 32U );
	acc1 = (uint32_t)d;
	d = (uint64_t)acc2 + ctx->s[2] + ( d >> 32U );
	acc2 = (uint32_t)d;
	acc3 += ctx->s[3] + (uint32_t)( d >> 32U );

	/* Compute MAC (128 least significant bits of the accumulator) */
	mac[0] = (uint8_t)acc0;
	mac[1] = (uint8_t)( acc0 >> 8 );
	mac[2] = (uint8_t)( acc0 >> 16 );
	mac[3] = (uint8_t)( acc0 >> 24 );
	mac[4] = (uint8_t)acc1;
	mac[5] = (uint8_t)( acc1 >> 8 );
	mac[6] = (uint8_t)( acc1 >> 16 );
	mac[7] = (uint8_t)( acc1 >> 24 );
	mac[8] = (uint8_t)acc2;
	mac[9] = (uint8_t)( acc2 >> 8 );
	mac[10] = (uint8_t)( acc2 >> 16 );
	mac[11] = (uint8_t)( acc2 >> 24 );
	mac[12] = (uint8_t)acc3;
	mac[13] = (uint8_t)( acc3 >> 8 );
	mac[14] = (uint8_t)( acc3 >> 16 );
	mac[15] = (uint8_t)( acc3 >> 24 );
	}

	void mbedtls_poly1305_init( mbedtls_poly1305_context *ctx )
	{
	if ( ctx != NULL )
	{
	mbedtls_zeroize( ctx, sizeof(mbedtls_poly1305_context) );
	}
	}

	void mbedtls_poly1305_free( mbedtls_poly1305_context *ctx )
	{
	if ( ctx != NULL )
	{
	mbedtls_zeroize( ctx, sizeof(mbedtls_poly1305_context) );
	}
	}

	int mbedtls_poly1305_setkey( mbedtls_poly1305_context *ctx,
	const unsigned char key[32] )
	{
	if ( ctx == NULL )
	{
	return( MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA );
	}

	/* r &= 0x0ffffffc0ffffffc0ffffffc0fffffff */
	ctx->r[0] = BYTES_TO_U32_LE( key, 0 ) & 0x0FFFFFFFU;
	ctx->r[1] = BYTES_TO_U32_LE( key, 4 ) & 0x0FFFFFFCU;
	ctx->r[2] = BYTES_TO_U32_LE( key, 8 ) & 0x0FFFFFFCU;
	ctx->r[3] = BYTES_TO_U32_LE( key, 12 ) & 0x0FFFFFFCU;

	ctx->s[0] = BYTES_TO_U32_LE( key, 16 );
	ctx->s[1] = BYTES_TO_U32_LE( key, 20 );
	ctx->s[2] = BYTES_TO_U32_LE( key, 24 );
	ctx->s[3] = BYTES_TO_U32_LE( key, 28 );

	/* Initial accumulator state */
	ctx->acc[0] = 0U;
	ctx->acc[1] = 0U;
	ctx->acc[2] = 0U;
	ctx->acc[3] = 0U;

	return 0;
	}

	int mbedtls_poly1305_update( mbedtls_poly1305_context *ctx,
	size_t ilen,
	const unsigned char* input )
	{
	size_t offset = 0U;
	size_t remaining = ilen;
	size_t queue_free_len;
	size_t nblocks;

	if ( ( ctx == NULL ) \|\| ( input == NULL ) )
	{
	return( MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA );
	}

	if ( ctx->queue_len > 0U )
	{
	queue_free_len = ( POLY1305_BLOCK_SIZE_BYTES - ctx->queue_len );

	if ( ilen < queue_free_len )
	{
	/* Not enough data to complete the block.
	* Store this data with the other leftovers.
	*/
	memcpy( &ctx->queue[ctx->queue_len],
	input,
	ilen );

	ctx->queue_len += ilen;

	remaining = 0U;
	}
	else
	{
	/* Enough data to produce a complete block */
	memcpy( &ctx->queue[ctx->queue_len],
	input,
	queue_free_len );

	ctx->queue_len = 0U;

	mbedtls_poly1305_process( ctx,
	1U,
	ctx->queue,
	1U ); /* add padding bit */

	offset += queue_free_len;
	remaining -= queue_free_len;
	}
	}

	if ( remaining >= POLY1305_BLOCK_SIZE_BYTES )
	{
	nblocks = remaining / POLY1305_BLOCK_SIZE_BYTES;

	mbedtls_poly1305_process( ctx, nblocks, &input[offset], 1U );

	offset += nblocks * POLY1305_BLOCK_SIZE_BYTES;
	remaining %= POLY1305_BLOCK_SIZE_BYTES;
	}

	if ( remaining > 0U )
	{
	/* Store partial block */
	ctx->queue_len = remaining;
	memcpy( ctx->queue, &input[offset], remaining );
	}

	return( 0 );
	}

	int mbedtls_poly1305_finish( mbedtls_poly1305_context *ctx,
	unsigned char mac[16] )
	{
	if ( ( ctx == NULL ) \|\| ( mac == NULL ) )
	{
	return( MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA );
	}

	/* Process any leftover data */
	if ( ctx->queue_len > 0U )
	{
	/* Add padding bit */
	ctx->queue[ctx->queue_len] = 1U;
	ctx->queue_len++;

	/* Pad with zeroes */
	memset( &ctx->queue[ctx->queue_len],
	0,
	POLY1305_BLOCK_SIZE_BYTES - ctx->queue_len );

	mbedtls_poly1305_process( ctx,
	1U, /* Process 1 block */
	ctx->queue,
	0U ); /* Don't add padding bit (it was just added above) */
	}

	mbedtls_poly1305_compute_mac( ctx, mac );

	return( 0 );
	}

	#endif /* MBEDTLS_POLY1305_ALT */

	int mbedtls_poly1305_mac( const unsigned char key[32],
	size_t ilen,
	const unsigned char *input,
	unsigned char mac[16] )
	{
	mbedtls_poly1305_context ctx;
	int result;

	mbedtls_poly1305_init( &ctx );

	result = mbedtls_poly1305_setkey( &ctx, key );
	if ( result != 0 )
	goto cleanup;

	result = mbedtls_poly1305_update( &ctx, ilen, input );
	if ( result != 0 )
	goto cleanup;

	result = mbedtls_poly1305_finish( &ctx, mac );

	cleanup:
	mbedtls_poly1305_free( &ctx );
	return( 0 );
	}

	#if defined(MBEDTLS_SELF_TEST)

	static const unsigned char test_keys[2][32] =
	{
	{
	0x85, 0xd6, 0xbe, 0x78, 0x57, 0x55, 0x6d, 0x33,
	0x7f, 0x44, 0x52, 0xfe, 0x42, 0xd5, 0x06, 0xa8,
	0x01, 0x03, 0x80, 0x8a, 0xfb, 0x0d, 0xb2, 0xfd,
	0x4a, 0xbf, 0xf6, 0xaf, 0x41, 0x49, 0xf5, 0x1b
	},
	{
	0x1c, 0x92, 0x40, 0xa5, 0xeb, 0x55, 0xd3, 0x8a,
	0xf3, 0x33, 0x88, 0x86, 0x04, 0xf6, 0xb5, 0xf0,
	0x47, 0x39, 0x17, 0xc1, 0x40, 0x2b, 0x80, 0x09,
	0x9d, 0xca, 0x5c, 0xbc, 0x20, 0x70, 0x75, 0xc0
	}
	};

	static const unsigned char test_data[2][127] =
	{
	{
	0x43, 0x72, 0x79, 0x70, 0x74, 0x6f, 0x67, 0x72,
	0x61, 0x70, 0x68, 0x69, 0x63, 0x20, 0x46, 0x6f,
	0x72, 0x75, 0x6d, 0x20, 0x52, 0x65, 0x73, 0x65,
	0x61, 0x72, 0x63, 0x68, 0x20, 0x47, 0x72, 0x6f,
	0x75, 0x70
	},
	{
	0x27, 0x54, 0x77, 0x61, 0x73, 0x20, 0x62, 0x72,
	0x69, 0x6c, 0x6c, 0x69, 0x67, 0x2c, 0x20, 0x61,
	0x6e, 0x64, 0x20, 0x74, 0x68, 0x65, 0x20, 0x73,
	0x6c, 0x69, 0x74, 0x68, 0x79, 0x20, 0x74, 0x6f,
	0x76, 0x65, 0x73, 0x0a, 0x44, 0x69, 0x64, 0x20,
	0x67, 0x79, 0x72, 0x65, 0x20, 0x61, 0x6e, 0x64,
	0x20, 0x67, 0x69, 0x6d, 0x62, 0x6c, 0x65, 0x20,
	0x69, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x77,
	0x61, 0x62, 0x65, 0x3a, 0x0a, 0x41, 0x6c, 0x6c,
	0x20, 0x6d, 0x69, 0x6d, 0x73, 0x79, 0x20, 0x77,
	0x65, 0x72, 0x65, 0x20, 0x74, 0x68, 0x65, 0x20,
	0x62, 0x6f, 0x72, 0x6f, 0x67, 0x6f, 0x76, 0x65,
	0x73, 0x2c, 0x0a, 0x41, 0x6e, 0x64, 0x20, 0x74,
	0x68, 0x65, 0x20, 0x6d, 0x6f, 0x6d, 0x65, 0x20,
	0x72, 0x61, 0x74, 0x68, 0x73, 0x20, 0x6f, 0x75,
	0x74, 0x67, 0x72, 0x61, 0x62, 0x65, 0x2e
	}
	};

	static const size_t test_data_len[2] =
	{
	34U,
	127U
	};

	static const unsigned char test_mac[2][16] =
	{
	{
	0xa8, 0x06, 0x1d, 0xc1, 0x30, 0x51, 0x36, 0xc6,
	0xc2, 0x2b, 0x8b, 0xaf, 0x0c, 0x01, 0x27, 0xa9
	},
	{
	0x45, 0x41, 0x66, 0x9a, 0x7e, 0xaa, 0xee, 0x61,
	0xe7, 0x08, 0xdc, 0x7c, 0xbc, 0xc5, 0xeb, 0x62
	}
	};

	int mbedtls_poly1305_self_test( int verbose )
	{
	uint8_t mac[16];
	size_t i;
	int result;

	for ( i = 0U; i < 2U; i++ )
	{
	result = mbedtls_poly1305_mac( test_keys[i],
	test_data_len[i],
	test_data[i],
	mac );
	if ( result != 0 )
	{
	if ( verbose != 0 )
	{
	mbedtls_printf( "Poly1305 test %zi error code: %i\n", i, result );
	}

	return( -1 );
	}

	if ( memcmp( mac, test_mac[i], 16U ) != 0 )
	{
	if ( verbose != 0 )
	{
	mbedtls_printf( "Poly1305 test %zi failed\n", i );
	}

	return( -1 );
	}
	}

	return( 0 );
	}

	#endif /* MBEDTLS_SELF_TEST */

	#endif /* MBEDTLS_POLY1305_C */