text: /*
   *  NIST SP800-38C compliant CCM implementation
   *
   *  Copyright (C) 2006-2015, 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)
   */
  
  /*
   * Definition of CCM:
   * http://csrc.nist.gov/publications/nistpubs/800-38C/SP800-38C_updated-July20_2007.pdf
   * RFC 3610 "Counter with CBC-MAC (CCM)"
   *
   * Related:
   * RFC 5116 "An Interface and Algorithms for Authenticated Encryption"
   */
  
  #if !defined(MBEDTLS_CONFIG_FILE)
  #include "mbedtls/config.h"
  #else
  #include MBEDTLS_CONFIG_FILE
  #endif
  
  #if defined(MBEDTLS_CCM_C)
  
  #include "mbedtls/ccm.h"
  #include "mbedtls/platform_util.h"
  
  #include <string.h>
  
  #if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
  #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 && MBEDTLS_AES_C */
  
  #if !defined(MBEDTLS_CCM_ALT)
  
  #define CCM_ENCRYPT 0
  #define CCM_DECRYPT 1
  
  /*
   * Initialize context
   */
  void mbedtls_ccm_init( mbedtls_ccm_context *ctx )
  {
      memset( ctx, 0, sizeof( mbedtls_ccm_context ) );
  }
  
  int mbedtls_ccm_setkey( mbedtls_ccm_context *ctx,
                          mbedtls_cipher_id_t cipher,
                          const unsigned char *key,
                          unsigned int keybits )
  {
      int ret;
      const mbedtls_cipher_info_t *cipher_info;
  
      cipher_info = mbedtls_cipher_info_from_values( cipher, keybits, MBEDTLS_MODE_ECB );
      if( cipher_info == NULL )
          return( MBEDTLS_ERR_CCM_BAD_INPUT );
  
      if( cipher_info->block_size != 16 )
          return( MBEDTLS_ERR_CCM_BAD_INPUT );
  
      mbedtls_cipher_free( &ctx->cipher_ctx );
  
      if( ( ret = mbedtls_cipher_setup( &ctx->cipher_ctx, cipher_info ) ) != 0 )
          return( ret );
  
      if( ( ret = mbedtls_cipher_setkey( &ctx->cipher_ctx, key, keybits,
                                 MBEDTLS_ENCRYPT ) ) != 0 )
      {
          return( ret );
      }
  
      return( 0 );
  }
  
  /*
   * Free context
   */
  void mbedtls_ccm_free( mbedtls_ccm_context *ctx )
  {
      mbedtls_cipher_free( &ctx->cipher_ctx );
      mbedtls_platform_zeroize( ctx, sizeof( mbedtls_ccm_context ) );
  }
  
  /*
   * Macros for common operations.
   * Results in smaller compiled code than static inline functions.
   */
  
  /*
   * Update the CBC-MAC state in y using a block in b
   * (Always using b as the source helps the compiler optimise a bit better.)
   */
  #define UPDATE_CBC_MAC                                                      \
      for( i = 0; i < 16; i++ )                                               \
          y[i] ^= b[i];                                                       \
                                                                              \
      if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, y, 16, y, &olen ) ) != 0 ) \
          return( ret );
  
  /*
   * Encrypt or decrypt a partial block with CTR
   * Warning: using b for temporary storage! src and dst must not be b!
   * This avoids allocating one more 16 bytes buffer while allowing src == dst.
   */
  #define CTR_CRYPT( dst, src, len  )                                            \
      if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, ctr, 16, b, &olen ) ) != 0 )  \
          return( ret );                                                         \
                                                                                 \
      for( i = 0; i < len; i++ )                                                 \
          dst[i] = src[i] ^ b[i];
  
  /*
   * Authenticated encryption or decryption
   */
  #if !defined(MBEDTLS_CCM_CRYPT_ALT)
  /* CCM selftest fails on ARM Cortex M with IAR 8.11 with common subexpression elimination optimalization enabled */
  #if defined(__ICCARM__)
  #pragma optimize=no_cse
  #endif
  static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length,
                             const unsigned char *iv, size_t iv_len,
                             const unsigned char *add, size_t add_len,
                             const unsigned char *input, unsigned char *output,
                             unsigned char *tag, size_t tag_len )
  {
      int ret;
      unsigned char i;
      unsigned char q;
      size_t len_left, olen;
      unsigned char b[16];
      unsigned char y[16];
      unsigned char ctr[16];
      const unsigned char *src;
      unsigned char *dst;
  
      /*
       * Check length requirements: SP800-38C A.1
       * Additional requirement: a < 2^16 - 2^8 to simplify the code.
       * 'length' checked later (when writing it to the first block)
       *
       * Also, loosen the requirements to enable support for CCM* (IEEE 802.15.4).
       */
      if( tag_len == 2 || tag_len > 16 || tag_len % 2 != 0 )
          return( MBEDTLS_ERR_CCM_BAD_INPUT );
  
      /* Also implies q is within bounds */
      if( iv_len < 7 || iv_len > 13 )
          return( MBEDTLS_ERR_CCM_BAD_INPUT );
  
      if( add_len > 0xFF00 )
          return( MBEDTLS_ERR_CCM_BAD_INPUT );
  
      q = 16 - 1 - (unsigned char) iv_len;
  
      /*
       * First block B_0:
       * 0        .. 0        flags
       * 1        .. iv_len   nonce (aka iv)
       * iv_len+1 .. 15       length
       *
       * With flags as (bits):
       * 7        0
       * 6        add present?
       * 5 .. 3   (t - 2) / 2
       * 2 .. 0   q - 1
       */
      b[0] = 0;
      b[0] |= ( add_len > 0 ) << 6;
      b[0] |= ( ( tag_len - 2 ) / 2 ) << 3;
      b[0] |= q - 1;
  
      memcpy( b + 1, iv, iv_len );
  
      for( i = 0, len_left = length; i < q; i++, len_left >>= 8 )
          b[15-i] = (unsigned char)( len_left & 0xFF );
  
      if( len_left > 0 )
          return( MBEDTLS_ERR_CCM_BAD_INPUT );
  
  
      /* Start CBC-MAC with first block */
      memset( y, 0, 16 );
      UPDATE_CBC_MAC;
  
      /*
       * If there is additional data, update CBC-MAC with
       * add_len, add, 0 (padding to a block boundary)
       */
      if( add_len > 0 )
      {
          size_t use_len;
          len_left = add_len;
          src = add;
  
          memset( b, 0, 16 );
          b[0] = (unsigned char)( ( add_len >> 8 ) & 0xFF );
          b[1] = (unsigned char)( ( add_len      ) & 0xFF );
  
          use_len = len_left < 16 - 2 ? len_left : 16 - 2;
          memcpy( b + 2, src, use_len );
          len_left -= use_len;
          src += use_len;
  
          UPDATE_CBC_MAC;
  
          while( len_left > 0 )
          {
              use_len = len_left > 16 ? 16 : len_left;
  
              memset( b, 0, 16 );
              memcpy( b, src, use_len );
              UPDATE_CBC_MAC;
  
              len_left -= use_len;
              src += use_len;
          }
      }
  
      /*
       * Prepare counter block for encryption:
       * 0        .. 0        flags
       * 1        .. iv_len   nonce (aka iv)
       * iv_len+1 .. 15       counter (initially 1)
       *
       * With flags as (bits):
       * 7 .. 3   0
       * 2 .. 0   q - 1
       */
      ctr[0] = q - 1;
      memcpy( ctr + 1, iv, iv_len );
      memset( ctr + 1 + iv_len, 0, q );
      ctr[15] = 1;
  
      /*
       * Authenticate and {en,de}crypt the message.
       *
       * The only difference between encryption and decryption is
       * the respective order of authentication and {en,de}cryption.
       */
      len_left = length;
      src = input;
      dst = output;
  
      while( len_left > 0 )
      {
          size_t use_len = len_left > 16 ? 16 : len_left;
  
          if( mode == CCM_ENCRYPT )
          {
              memset( b, 0, 16 );
              memcpy( b, src, use_len );
              UPDATE_CBC_MAC;
          }
  
          CTR_CRYPT( dst, src, use_len );
  
          if( mode == CCM_DECRYPT )
          {
              memset( b, 0, 16 );
              memcpy( b, dst, use_len );
              UPDATE_CBC_MAC;
          }
  
          dst += use_len;
          src += use_len;
          len_left -= use_len;
  
          /*
           * Increment counter.
           * No need to check for overflow thanks to the length check above.
           */
          for( i = 0; i < q; i++ )
              if( ++ctr[15-i] != 0 )
                  break;
      }
  
      /*
       * Authentication: reset counter and crypt/mask internal tag
       */
      for( i = 0; i < q; i++ )
          ctr[15-i] = 0;
  
      CTR_CRYPT( y, y, 16 );
      memcpy( tag, y, tag_len );
  
      return( 0 );
  }
  
  /*
   * Authenticated encryption
   */
  int mbedtls_ccm_star_encrypt_and_tag( mbedtls_ccm_context *ctx, size_t length,
                           const unsigned char *iv, size_t iv_len,
                           const unsigned char *add, size_t add_len,
                           const unsigned char *input, unsigned char *output,
                           unsigned char *tag, size_t tag_len )
  {
      return( ccm_auth_crypt( ctx, CCM_ENCRYPT, length, iv, iv_len,
                              add, add_len, input, output, tag, tag_len ) );
  }
  
  int mbedtls_ccm_encrypt_and_tag( mbedtls_ccm_context *ctx, size_t length,
                           const unsigned char *iv, size_t iv_len,
                           const unsigned char *add, size_t add_len,
                           const unsigned char *input, unsigned char *output,
                           unsigned char *tag, size_t tag_len )
  {
      if( tag_len == 0 )
          return( MBEDTLS_ERR_CCM_BAD_INPUT );
  
      return( mbedtls_ccm_star_encrypt_and_tag( ctx, length, iv, iv_len, add,
                  add_len, input, output, tag, tag_len ) );
  }
  
  /*
   * Authenticated decryption
   */
  int mbedtls_ccm_star_auth_decrypt( mbedtls_ccm_context *ctx, size_t length,
                        const unsigned char *iv, size_t iv_len,
                        const unsigned char *add, size_t add_len,
                        const unsigned char *input, unsigned char *output,
                        const unsigned char *tag, size_t tag_len )
  {
      int ret;
      unsigned char check_tag[16];
      unsigned char i;
      int diff;
  
      if( ( ret = ccm_auth_crypt( ctx, CCM_DECRYPT, length,
                                  iv, iv_len, add, add_len,
                                  input, output, check_tag, tag_len ) ) != 0 )
      {
          return( ret );
      }
  
      /* Check tag in "constant-time" */
      for( diff = 0, i = 0; i < tag_len; i++ )
          diff |= tag[i] ^ check_tag[i];
  
      if( diff != 0 )
      {
          mbedtls_platform_zeroize( output, length );
          return( MBEDTLS_ERR_CCM_AUTH_FAILED );
      }
  
      return( 0 );
  }
  
  int mbedtls_ccm_auth_decrypt( mbedtls_ccm_context *ctx, size_t length,
                        const unsigned char *iv, size_t iv_len,
                        const unsigned char *add, size_t add_len,
                        const unsigned char *input, unsigned char *output,
                        const unsigned char *tag, size_t tag_len )
  {
      if( tag_len == 0 )
          return( MBEDTLS_ERR_CCM_BAD_INPUT );
  
      return( mbedtls_ccm_star_auth_decrypt( ctx, length, iv, iv_len, add,
                  add_len, input, output, tag, tag_len ) );
  }
  #endif /* !MBEDTLS_CCM_CRYPT_ALT */
  #endif /* !MBEDTLS_CCM_ALT */
  
  #if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
  /*
   * Examples 1 to 3 from SP800-38C Appendix C
   */
  
  #define NB_TESTS 3
  #define CCM_SELFTEST_PT_MAX_LEN 24
  #define CCM_SELFTEST_CT_MAX_LEN 32
  /*
   * The data is the same for all tests, only the used length changes
   */
  static const unsigned char key[] = {
      0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,
      0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f
  };
  
  static const unsigned char iv[] = {
      0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
      0x18, 0x19, 0x1a, 0x1b
  };
  
  static const unsigned char ad[] = {
      0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
      0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
      0x10, 0x11, 0x12, 0x13
  };
  
  static const unsigned char msg[CCM_SELFTEST_PT_MAX_LEN] = {
      0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
      0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
      0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
  };
  
  static const size_t iv_len [NB_TESTS] = { 7, 8,  12 };
  static const size_t add_len[NB_TESTS] = { 8, 16, 20 };
  static const size_t msg_len[NB_TESTS] = { 4, 16, 24 };
  static const size_t tag_len[NB_TESTS] = { 4, 6,  8  };
  
  static const unsigned char res[NB_TESTS][CCM_SELFTEST_CT_MAX_LEN] = {
      {   0x71, 0x62, 0x01, 0x5b, 0x4d, 0xac, 0x25, 0x5d },
      {   0xd2, 0xa1, 0xf0, 0xe0, 0x51, 0xea, 0x5f, 0x62,
          0x08, 0x1a, 0x77, 0x92, 0x07, 0x3d, 0x59, 0x3d,
          0x1f, 0xc6, 0x4f, 0xbf, 0xac, 0xcd },
      {   0xe3, 0xb2, 0x01, 0xa9, 0xf5, 0xb7, 0x1a, 0x7a,
          0x9b, 0x1c, 0xea, 0xec, 0xcd, 0x97, 0xe7, 0x0b,
          0x61, 0x76, 0xaa, 0xd9, 0xa4, 0x42, 0x8a, 0xa5,
          0x48, 0x43, 0x92, 0xfb, 0xc1, 0xb0, 0x99, 0x51 }
  };
  
  int mbedtls_ccm_self_test( int verbose )
  {
      mbedtls_ccm_context ctx;
      /*
       * Some hardware accelerators require the input and output buffers
       * would be in RAM, because the flash is not accessible.
       * Use buffers on the stack to hold the test vectors data.
       */
      unsigned char plaintext[CCM_SELFTEST_PT_MAX_LEN];
      unsigned char ciphertext[CCM_SELFTEST_CT_MAX_LEN];
      size_t i;
      int ret;
  
      mbedtls_ccm_init( &ctx );
  
      if( mbedtls_ccm_setkey( &ctx, MBEDTLS_CIPHER_ID_AES, key, 8 * sizeof key ) != 0 )
      {
          if( verbose != 0 )
              mbedtls_printf( "  CCM: setup failed" );
  
          return( 1 );
      }
  
      for( i = 0; i < NB_TESTS; i++ )
      {
          if( verbose != 0 )
              mbedtls_printf( "  CCM-AES #%u: ", (unsigned int) i + 1 );
  
          memset( plaintext, 0, CCM_SELFTEST_PT_MAX_LEN );
          memset( ciphertext, 0, CCM_SELFTEST_CT_MAX_LEN );
          memcpy( plaintext, msg, msg_len[i] );
  
          ret = mbedtls_ccm_encrypt_and_tag( &ctx, msg_len[i],
                                             iv, iv_len[i], ad, add_len[i],
                                             plaintext, ciphertext,
                                             ciphertext + msg_len[i], tag_len[i] );
  
          if( ret != 0 ||
              memcmp( ciphertext, res[i], msg_len[i] + tag_len[i] ) != 0 )
          {
              if( verbose != 0 )
                  mbedtls_printf( "failed\n\r" );
  
              return( 1 );
          }
          memset( plaintext, 0, CCM_SELFTEST_PT_MAX_LEN );
  
          ret = mbedtls_ccm_auth_decrypt( &ctx, msg_len[i],
                                          iv, iv_len[i], ad, add_len[i],
                                          ciphertext, plaintext,
                                          ciphertext + msg_len[i], tag_len[i] );
  
          if( ret != 0 ||
              memcmp( plaintext, msg, msg_len[i] ) != 0 )
          {
              if( verbose != 0 )
                  mbedtls_printf( "failed\n\r" );
  
              return( 1 );
          }
  
          if( verbose != 0 )
              mbedtls_printf( "passed\n\r" );
      }
  
      mbedtls_ccm_free( &ctx );
  
      if( verbose != 0 )
          mbedtls_printf( "\n\r" );
  
      return( 0 );
  }
  
  #endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */
  
  #endif /* MBEDTLS_CCM_C */
  