text: /**
   * \file chacha20.c
   *
   * \brief ChaCha20 cipher.
   *
   * \author Daniel King <damaki.gh@gmail.com>
   *
   *  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 "config.h"
  #else
  #include MBEDTLS_CONFIG_FILE
  #endif
  
  #if defined(MBEDTLS_CHACHA20_C)
  
  #include "chacha20.h"
  #include "platform_util.h"
  
  #include <stddef.h>
  #include <string.h>
  
  #if defined(MBEDTLS_SELF_TEST)
  #if defined(MBEDTLS_PLATFORM_C)
  #include "platform.h"
  #else
  #include <stdio.h>
  #define mbedtls_printf printf
  #endif /* MBEDTLS_PLATFORM_C */
  #endif /* MBEDTLS_SELF_TEST */
  
  #if !defined(MBEDTLS_CHACHA20_ALT)
  
  #if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
      !defined(inline) && !defined(__cplusplus)
  #define inline __inline
  #endif
  
  /* Parameter validation macros */
  #define CHACHA20_VALIDATE_RET( cond )                                       \
      MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA )
  #define CHACHA20_VALIDATE( cond )                                           \
      MBEDTLS_INTERNAL_VALIDATE( cond )
  
  #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 )  \
      )
  
  #define ROTL32( value, amount ) \
          ( (uint32_t) ( value << amount ) | ( value >> ( 32 - amount ) ) )
  
  #define CHACHA20_CTR_INDEX ( 12U )
  
  #define CHACHA20_BLOCK_SIZE_BYTES ( 4U * 16U )
  
  /**
   * \brief           ChaCha20 quarter round operation.
   *
   *                  The quarter round is defined as follows (from RFC 7539):
   *                      1.  a += b; d ^= a; d <<<= 16;
   *                      2.  c += d; b ^= c; b <<<= 12;
   *                      3.  a += b; d ^= a; d <<<= 8;
   *                      4.  c += d; b ^= c; b <<<= 7;
   *
   * \param state     ChaCha20 state to modify.
   * \param a         The index of 'a' in the state.
   * \param b         The index of 'b' in the state.
   * \param c         The index of 'c' in the state.
   * \param d         The index of 'd' in the state.
   */
  static inline void chacha20_quarter_round( uint32_t state[16],
          size_t a,
          size_t b,
          size_t c,
          size_t d )
  {
      /* a += b; d ^= a; d <<<= 16; */
      state[a] += state[b];
      state[d] ^= state[a];
      state[d] = ROTL32( state[d], 16 );
  
      /* c += d; b ^= c; b <<<= 12 */
      state[c] += state[d];
      state[b] ^= state[c];
      state[b] = ROTL32( state[b], 12 );
  
      /* a += b; d ^= a; d <<<= 8; */
      state[a] += state[b];
      state[d] ^= state[a];
      state[d] = ROTL32( state[d], 8 );
  
      /* c += d; b ^= c; b <<<= 7; */
      state[c] += state[d];
      state[b] ^= state[c];
      state[b] = ROTL32( state[b], 7 );
  }
  
  /**
   * \brief           Perform the ChaCha20 inner block operation.
   *
   *                  This function performs two rounds: the column round and the
   *                  diagonal round.
   *
   * \param state     The ChaCha20 state to update.
   */
  static void chacha20_inner_block( uint32_t state[16] )
  {
      chacha20_quarter_round( state, 0, 4, 8,  12 );
      chacha20_quarter_round( state, 1, 5, 9,  13 );
      chacha20_quarter_round( state, 2, 6, 10, 14 );
      chacha20_quarter_round( state, 3, 7, 11, 15 );
  
      chacha20_quarter_round( state, 0, 5, 10, 15 );
      chacha20_quarter_round( state, 1, 6, 11, 12 );
      chacha20_quarter_round( state, 2, 7, 8,  13 );
      chacha20_quarter_round( state, 3, 4, 9,  14 );
  }
  
  /**
   * \brief               Generates a keystream block.
   *
   * \param initial_state The initial ChaCha20 state (key, nonce, counter).
   * \param keystream     Generated keystream bytes are written to this buffer.
   */
  static void chacha20_block( const uint32_t initial_state[16],
                              unsigned char keystream[64] )
  {
      uint32_t working_state[16];
      size_t i;
  
      memcpy( working_state,
              initial_state,
              CHACHA20_BLOCK_SIZE_BYTES );
  
      for( i = 0U; i < 10U; i++ )
          chacha20_inner_block( working_state );
  
      working_state[ 0] += initial_state[ 0];
      working_state[ 1] += initial_state[ 1];
      working_state[ 2] += initial_state[ 2];
      working_state[ 3] += initial_state[ 3];
      working_state[ 4] += initial_state[ 4];
      working_state[ 5] += initial_state[ 5];
      working_state[ 6] += initial_state[ 6];
      working_state[ 7] += initial_state[ 7];
      working_state[ 8] += initial_state[ 8];
      working_state[ 9] += initial_state[ 9];
      working_state[10] += initial_state[10];
      working_state[11] += initial_state[11];
      working_state[12] += initial_state[12];
      working_state[13] += initial_state[13];
      working_state[14] += initial_state[14];
      working_state[15] += initial_state[15];
  
      for( i = 0U; i < 16; i++ )
      {
          size_t offset = i * 4U;
  
          keystream[offset     ] = (unsigned char)( working_state[i]       );
          keystream[offset + 1U] = (unsigned char)( working_state[i] >>  8 );
          keystream[offset + 2U] = (unsigned char)( working_state[i] >> 16 );
          keystream[offset + 3U] = (unsigned char)( working_state[i] >> 24 );
      }
  
      mbedtls_platform_zeroize( working_state, sizeof( working_state ) );
  }
  
  void mbedtls_chacha20_init( mbedtls_chacha20_context *ctx )
  {
      CHACHA20_VALIDATE( ctx != NULL );
  
      mbedtls_platform_zeroize( ctx->state, sizeof( ctx->state ) );
      mbedtls_platform_zeroize( ctx->keystream8, sizeof( ctx->keystream8 ) );
  
      /* Initially, there's no keystream bytes available */
      ctx->keystream_bytes_used = CHACHA20_BLOCK_SIZE_BYTES;
  }
  
  void mbedtls_chacha20_free( mbedtls_chacha20_context *ctx )
  {
      if( ctx != NULL )
      {
          mbedtls_platform_zeroize( ctx, sizeof( mbedtls_chacha20_context ) );
      }
  }
  
  int mbedtls_chacha20_setkey( mbedtls_chacha20_context *ctx,
                               const unsigned char key[32] )
  {
      CHACHA20_VALIDATE_RET( ctx != NULL );
      CHACHA20_VALIDATE_RET( key != NULL );
  
      /* ChaCha20 constants - the string "expand 32-byte k" */
      ctx->state[0] = 0x61707865;
      ctx->state[1] = 0x3320646e;
      ctx->state[2] = 0x79622d32;
      ctx->state[3] = 0x6b206574;
  
      /* Set key */
      ctx->state[4]  = BYTES_TO_U32_LE( key, 0 );
      ctx->state[5]  = BYTES_TO_U32_LE( key, 4 );
      ctx->state[6]  = BYTES_TO_U32_LE( key, 8 );
      ctx->state[7]  = BYTES_TO_U32_LE( key, 12 );
      ctx->state[8]  = BYTES_TO_U32_LE( key, 16 );
      ctx->state[9]  = BYTES_TO_U32_LE( key, 20 );
      ctx->state[10] = BYTES_TO_U32_LE( key, 24 );
      ctx->state[11] = BYTES_TO_U32_LE( key, 28 );
  
      return( 0 );
  }
  
  int mbedtls_chacha20_starts( mbedtls_chacha20_context* ctx,
                               const unsigned char nonce[12],
                               uint32_t counter )
  {
      CHACHA20_VALIDATE_RET( ctx != NULL );
      CHACHA20_VALIDATE_RET( nonce != NULL );
  
      /* Counter */
      ctx->state[12] = counter;
  
      /* Nonce */
      ctx->state[13] = BYTES_TO_U32_LE( nonce, 0 );
      ctx->state[14] = BYTES_TO_U32_LE( nonce, 4 );
      ctx->state[15] = BYTES_TO_U32_LE( nonce, 8 );
  
      mbedtls_platform_zeroize( ctx->keystream8, sizeof( ctx->keystream8 ) );
  
      /* Initially, there's no keystream bytes available */
      ctx->keystream_bytes_used = CHACHA20_BLOCK_SIZE_BYTES;
  
      return( 0 );
  }
  
  int mbedtls_chacha20_update( mbedtls_chacha20_context *ctx,
                               size_t size,
                               const unsigned char *input,
                               unsigned char *output )
  {
      size_t offset = 0U;
      size_t i;
  
      CHACHA20_VALIDATE_RET( ctx != NULL );
      CHACHA20_VALIDATE_RET( size == 0 || input  != NULL );
      CHACHA20_VALIDATE_RET( size == 0 || output != NULL );
  
      /* Use leftover keystream bytes, if available */
      while( size > 0U && ctx->keystream_bytes_used < CHACHA20_BLOCK_SIZE_BYTES )
      {
          output[offset] = input[offset]
                           ^ ctx->keystream8[ctx->keystream_bytes_used];
  
          ctx->keystream_bytes_used++;
          offset++;
          size--;
      }
  
      /* Process full blocks */
      while( size >= CHACHA20_BLOCK_SIZE_BYTES )
      {
          /* Generate new keystream block and increment counter */
          chacha20_block( ctx->state, ctx->keystream8 );
          ctx->state[CHACHA20_CTR_INDEX]++;
  
          for( i = 0U; i < 64U; i += 8U )
          {
              output[offset + i  ] = input[offset + i  ] ^ ctx->keystream8[i  ];
              output[offset + i+1] = input[offset + i+1] ^ ctx->keystream8[i+1];
              output[offset + i+2] = input[offset + i+2] ^ ctx->keystream8[i+2];
              output[offset + i+3] = input[offset + i+3] ^ ctx->keystream8[i+3];
              output[offset + i+4] = input[offset + i+4] ^ ctx->keystream8[i+4];
              output[offset + i+5] = input[offset + i+5] ^ ctx->keystream8[i+5];
              output[offset + i+6] = input[offset + i+6] ^ ctx->keystream8[i+6];
              output[offset + i+7] = input[offset + i+7] ^ ctx->keystream8[i+7];
          }
  
          offset += CHACHA20_BLOCK_SIZE_BYTES;
          size   -= CHACHA20_BLOCK_SIZE_BYTES;
      }
  
      /* Last (partial) block */
      if( size > 0U )
      {
          /* Generate new keystream block and increment counter */
          chacha20_block( ctx->state, ctx->keystream8 );
          ctx->state[CHACHA20_CTR_INDEX]++;
  
          for( i = 0U; i < size; i++)
          {
              output[offset + i] = input[offset + i] ^ ctx->keystream8[i];
          }
  
          ctx->keystream_bytes_used = size;
  
      }
  
      return( 0 );
  }
  
  int mbedtls_chacha20_crypt( const unsigned char key[32],
                              const unsigned char nonce[12],
                              uint32_t counter,
                              size_t data_len,
                              const unsigned char* input,
                              unsigned char* output )
  {
      mbedtls_chacha20_context ctx;
      int ret;
  
      CHACHA20_VALIDATE_RET( key != NULL );
      CHACHA20_VALIDATE_RET( nonce != NULL );
      CHACHA20_VALIDATE_RET( data_len == 0 || input  != NULL );
      CHACHA20_VALIDATE_RET( data_len == 0 || output != NULL );
  
      mbedtls_chacha20_init( &ctx );
  
      ret = mbedtls_chacha20_setkey( &ctx, key );
      if( ret != 0 )
          goto cleanup;
  
      ret = mbedtls_chacha20_starts( &ctx, nonce, counter );
      if( ret != 0 )
          goto cleanup;
  
      ret = mbedtls_chacha20_update( &ctx, data_len, input, output );
  
  cleanup:
      mbedtls_chacha20_free( &ctx );
      return( ret );
  }
  
  #endif /* !MBEDTLS_CHACHA20_ALT */
  
  #if defined(MBEDTLS_SELF_TEST)
  
  static const unsigned char test_keys[2][32] =
  {
      {
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
      },
      {
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01
      }
  };
  
  static const unsigned char test_nonces[2][12] =
  {
      {
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00
      },
      {
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x02
      }
  };
  
  static const uint32_t test_counters[2] =
  {
      0U,
      1U
  };
  
  static const unsigned char test_input[2][375] =
  {
      {
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
      },
      {
          0x41, 0x6e, 0x79, 0x20, 0x73, 0x75, 0x62, 0x6d,
          0x69, 0x73, 0x73, 0x69, 0x6f, 0x6e, 0x20, 0x74,
          0x6f, 0x20, 0x74, 0x68, 0x65, 0x20, 0x49, 0x45,
          0x54, 0x46, 0x20, 0x69, 0x6e, 0x74, 0x65, 0x6e,
          0x64, 0x65, 0x64, 0x20, 0x62, 0x79, 0x20, 0x74,
          0x68, 0x65, 0x20, 0x43, 0x6f, 0x6e, 0x74, 0x72,
          0x69, 0x62, 0x75, 0x74, 0x6f, 0x72, 0x20, 0x66,
          0x6f, 0x72, 0x20, 0x70, 0x75, 0x62, 0x6c, 0x69,
          0x63, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x20, 0x61,
          0x73, 0x20, 0x61, 0x6c, 0x6c, 0x20, 0x6f, 0x72,
          0x20, 0x70, 0x61, 0x72, 0x74, 0x20, 0x6f, 0x66,
          0x20, 0x61, 0x6e, 0x20, 0x49, 0x45, 0x54, 0x46,
          0x20, 0x49, 0x6e, 0x74, 0x65, 0x72, 0x6e, 0x65,
          0x74, 0x2d, 0x44, 0x72, 0x61, 0x66, 0x74, 0x20,
          0x6f, 0x72, 0x20, 0x52, 0x46, 0x43, 0x20, 0x61,
          0x6e, 0x64, 0x20, 0x61, 0x6e, 0x79, 0x20, 0x73,
          0x74, 0x61, 0x74, 0x65, 0x6d, 0x65, 0x6e, 0x74,
          0x20, 0x6d, 0x61, 0x64, 0x65, 0x20, 0x77, 0x69,
          0x74, 0x68, 0x69, 0x6e, 0x20, 0x74, 0x68, 0x65,
          0x20, 0x63, 0x6f, 0x6e, 0x74, 0x65, 0x78, 0x74,
          0x20, 0x6f, 0x66, 0x20, 0x61, 0x6e, 0x20, 0x49,
          0x45, 0x54, 0x46, 0x20, 0x61, 0x63, 0x74, 0x69,
          0x76, 0x69, 0x74, 0x79, 0x20, 0x69, 0x73, 0x20,
          0x63, 0x6f, 0x6e, 0x73, 0x69, 0x64, 0x65, 0x72,
          0x65, 0x64, 0x20, 0x61, 0x6e, 0x20, 0x22, 0x49,
          0x45, 0x54, 0x46, 0x20, 0x43, 0x6f, 0x6e, 0x74,
          0x72, 0x69, 0x62, 0x75, 0x74, 0x69, 0x6f, 0x6e,
          0x22, 0x2e, 0x20, 0x53, 0x75, 0x63, 0x68, 0x20,
          0x73, 0x74, 0x61, 0x74, 0x65, 0x6d, 0x65, 0x6e,
          0x74, 0x73, 0x20, 0x69, 0x6e, 0x63, 0x6c, 0x75,
          0x64, 0x65, 0x20, 0x6f, 0x72, 0x61, 0x6c, 0x20,
          0x73, 0x74, 0x61, 0x74, 0x65, 0x6d, 0x65, 0x6e,
          0x74, 0x73, 0x20, 0x69, 0x6e, 0x20, 0x49, 0x45,
          0x54, 0x46, 0x20, 0x73, 0x65, 0x73, 0x73, 0x69,
          0x6f, 0x6e, 0x73, 0x2c, 0x20, 0x61, 0x73, 0x20,
          0x77, 0x65, 0x6c, 0x6c, 0x20, 0x61, 0x73, 0x20,
          0x77, 0x72, 0x69, 0x74, 0x74, 0x65, 0x6e, 0x20,
          0x61, 0x6e, 0x64, 0x20, 0x65, 0x6c, 0x65, 0x63,
          0x74, 0x72, 0x6f, 0x6e, 0x69, 0x63, 0x20, 0x63,
          0x6f, 0x6d, 0x6d, 0x75, 0x6e, 0x69, 0x63, 0x61,
          0x74, 0x69, 0x6f, 0x6e, 0x73, 0x20, 0x6d, 0x61,
          0x64, 0x65, 0x20, 0x61, 0x74, 0x20, 0x61, 0x6e,
          0x79, 0x20, 0x74, 0x69, 0x6d, 0x65, 0x20, 0x6f,
          0x72, 0x20, 0x70, 0x6c, 0x61, 0x63, 0x65, 0x2c,
          0x20, 0x77, 0x68, 0x69, 0x63, 0x68, 0x20, 0x61,
          0x72, 0x65, 0x20, 0x61, 0x64, 0x64, 0x72, 0x65,
          0x73, 0x73, 0x65, 0x64, 0x20, 0x74, 0x6f
      }
  };
  
  static const unsigned char test_output[2][375] =
  {
      {
          0x76, 0xb8, 0xe0, 0xad, 0xa0, 0xf1, 0x3d, 0x90,
          0x40, 0x5d, 0x6a, 0xe5, 0x53, 0x86, 0xbd, 0x28,
          0xbd, 0xd2, 0x19, 0xb8, 0xa0, 0x8d, 0xed, 0x1a,
          0xa8, 0x36, 0xef, 0xcc, 0x8b, 0x77, 0x0d, 0xc7,
          0xda, 0x41, 0x59, 0x7c, 0x51, 0x57, 0x48, 0x8d,
          0x77, 0x24, 0xe0, 0x3f, 0xb8, 0xd8, 0x4a, 0x37,
          0x6a, 0x43, 0xb8, 0xf4, 0x15, 0x18, 0xa1, 0x1c,
          0xc3, 0x87, 0xb6, 0x69, 0xb2, 0xee, 0x65, 0x86
      },
      {
          0xa3, 0xfb, 0xf0, 0x7d, 0xf3, 0xfa, 0x2f, 0xde,
          0x4f, 0x37, 0x6c, 0xa2, 0x3e, 0x82, 0x73, 0x70,
          0x41, 0x60, 0x5d, 0x9f, 0x4f, 0x4f, 0x57, 0xbd,
          0x8c, 0xff, 0x2c, 0x1d, 0x4b, 0x79, 0x55, 0xec,
          0x2a, 0x97, 0x94, 0x8b, 0xd3, 0x72, 0x29, 0x15,
          0xc8, 0xf3, 0xd3, 0x37, 0xf7, 0xd3, 0x70, 0x05,
          0x0e, 0x9e, 0x96, 0xd6, 0x47, 0xb7, 0xc3, 0x9f,
          0x56, 0xe0, 0x31, 0xca, 0x5e, 0xb6, 0x25, 0x0d,
          0x40, 0x42, 0xe0, 0x27, 0x85, 0xec, 0xec, 0xfa,
          0x4b, 0x4b, 0xb5, 0xe8, 0xea, 0xd0, 0x44, 0x0e,
          0x20, 0xb6, 0xe8, 0xdb, 0x09, 0xd8, 0x81, 0xa7,
          0xc6, 0x13, 0x2f, 0x42, 0x0e, 0x52, 0x79, 0x50,
          0x42, 0xbd, 0xfa, 0x77, 0x73, 0xd8, 0xa9, 0x05,
          0x14, 0x47, 0xb3, 0x29, 0x1c, 0xe1, 0x41, 0x1c,
          0x68, 0x04, 0x65, 0x55, 0x2a, 0xa6, 0xc4, 0x05,
          0xb7, 0x76, 0x4d, 0x5e, 0x87, 0xbe, 0xa8, 0x5a,
          0xd0, 0x0f, 0x84, 0x49, 0xed, 0x8f, 0x72, 0xd0,
          0xd6, 0x62, 0xab, 0x05, 0x26, 0x91, 0xca, 0x66,
          0x42, 0x4b, 0xc8, 0x6d, 0x2d, 0xf8, 0x0e, 0xa4,
          0x1f, 0x43, 0xab, 0xf9, 0x37, 0xd3, 0x25, 0x9d,
          0xc4, 0xb2, 0xd0, 0xdf, 0xb4, 0x8a, 0x6c, 0x91,
          0x39, 0xdd, 0xd7, 0xf7, 0x69, 0x66, 0xe9, 0x28,
          0xe6, 0x35, 0x55, 0x3b, 0xa7, 0x6c, 0x5c, 0x87,
          0x9d, 0x7b, 0x35, 0xd4, 0x9e, 0xb2, 0xe6, 0x2b,
          0x08, 0x71, 0xcd, 0xac, 0x63, 0x89, 0x39, 0xe2,
          0x5e, 0x8a, 0x1e, 0x0e, 0xf9, 0xd5, 0x28, 0x0f,
          0xa8, 0xca, 0x32, 0x8b, 0x35, 0x1c, 0x3c, 0x76,
          0x59, 0x89, 0xcb, 0xcf, 0x3d, 0xaa, 0x8b, 0x6c,
          0xcc, 0x3a, 0xaf, 0x9f, 0x39, 0x79, 0xc9, 0x2b,
          0x37, 0x20, 0xfc, 0x88, 0xdc, 0x95, 0xed, 0x84,
          0xa1, 0xbe, 0x05, 0x9c, 0x64, 0x99, 0xb9, 0xfd,
          0xa2, 0x36, 0xe7, 0xe8, 0x18, 0xb0, 0x4b, 0x0b,
          0xc3, 0x9c, 0x1e, 0x87, 0x6b, 0x19, 0x3b, 0xfe,
          0x55, 0x69, 0x75, 0x3f, 0x88, 0x12, 0x8c, 0xc0,
          0x8a, 0xaa, 0x9b, 0x63, 0xd1, 0xa1, 0x6f, 0x80,
          0xef, 0x25, 0x54, 0xd7, 0x18, 0x9c, 0x41, 0x1f,
          0x58, 0x69, 0xca, 0x52, 0xc5, 0xb8, 0x3f, 0xa3,
          0x6f, 0xf2, 0x16, 0xb9, 0xc1, 0xd3, 0x00, 0x62,
          0xbe, 0xbc, 0xfd, 0x2d, 0xc5, 0xbc, 0xe0, 0x91,
          0x19, 0x34, 0xfd, 0xa7, 0x9a, 0x86, 0xf6, 0xe6,
          0x98, 0xce, 0xd7, 0x59, 0xc3, 0xff, 0x9b, 0x64,
          0x77, 0x33, 0x8f, 0x3d, 0xa4, 0xf9, 0xcd, 0x85,
          0x14, 0xea, 0x99, 0x82, 0xcc, 0xaf, 0xb3, 0x41,
          0xb2, 0x38, 0x4d, 0xd9, 0x02, 0xf3, 0xd1, 0xab,
          0x7a, 0xc6, 0x1d, 0xd2, 0x9c, 0x6f, 0x21, 0xba,
          0x5b, 0x86, 0x2f, 0x37, 0x30, 0xe3, 0x7c, 0xfd,
          0xc4, 0xfd, 0x80, 0x6c, 0x22, 0xf2, 0x21
      }
  };
  
  static const size_t test_lengths[2] =
  {
      64U,
      375U
  };
  
  #define ASSERT( cond, args )            \
      do                                  \
      {                                   \
          if( ! ( cond ) )                \
          {                               \
              if( verbose != 0 )          \
                  mbedtls_printf args;    \
                                          \
              return( -1 );               \
          }                               \
      }                                   \
      while( 0 )
  
  int mbedtls_chacha20_self_test( int verbose )
  {
      unsigned char output[381];
      unsigned i;
      int ret;
  
      for( i = 0U; i < 2U; i++ )
      {
          if( verbose != 0 )
              mbedtls_printf( "  ChaCha20 test %u ", i );
  
          ret = mbedtls_chacha20_crypt( test_keys[i],
                                        test_nonces[i],
                                        test_counters[i],
                                        test_lengths[i],
                                        test_input[i],
                                        output );
  
          ASSERT( 0 == ret, ( "error code: %i\n", ret ) );
  
          ASSERT( 0 == memcmp( output, test_output[i], test_lengths[i] ),
                  ( "failed (output)\n" ) );
  
          if( verbose != 0 )
              mbedtls_printf( "passed\n" );
      }
  
      if( verbose != 0 )
          mbedtls_printf( "\n" );
  
      return( 0 );
  }
  
  #endif /* MBEDTLS_SELF_TEST */
  
  #endif /* !MBEDTLS_CHACHA20_C */
  