text: /*
   *  MD5 hw acceleration
   *******************************************************************************
   * Copyright (c) 2017, STMicroelectronics
   *  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.
   *
   */
  #include "mbedtls/md5.h"
  #if defined(MBEDTLS_MD5_C)
  
  #if defined(MBEDTLS_MD5_ALT)
  #include "mbedtls/platform.h"
  
  /* 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;
  }
  
  static int st_md5_restore_hw_context(mbedtls_md5_context *ctx)
  {
      uint32_t i;
      uint32_t tickstart;
      /* allow multi-instance of HASH use: save context for HASH HW module CR */
      /* Check that there is no HASH activity on going */
      tickstart = HAL_GetTick();
      while ((HASH->SR & (HASH_FLAG_BUSY | HASH_FLAG_DMAS)) != 0) {
          if ((HAL_GetTick() - tickstart) > ST_MD5_TIMEOUT) {
              return 0; // timeout: HASH processor is busy
          }
      }
      HASH->STR = ctx->ctx_save_str;
      HASH->CR = (ctx->ctx_save_cr | HASH_CR_INIT);
      for (i=0;i<38;i++) {
          HASH->CSR[i] = ctx->ctx_save_csr[i];
      }
      return 1;
  }
  
  static int st_md5_save_hw_context(mbedtls_md5_context *ctx)
  {
      uint32_t i;
      uint32_t tickstart;
      /* Check that there is no HASH activity on going */
      tickstart = HAL_GetTick();
      while ((HASH->SR & (HASH_FLAG_BUSY | HASH_FLAG_DMAS)) != 0) {
          if ((HAL_GetTick() - tickstart) > ST_MD5_TIMEOUT) {
              return 0; // timeout: HASH processor is busy
          }
      }
      /* allow multi-instance of HASH use: restore context for HASH HW module CR */
      ctx->ctx_save_cr = HASH->CR;
      ctx->ctx_save_str = HASH->STR;
      for (i=0;i<38;i++) {
          ctx->ctx_save_csr[i] = HASH->CSR[i];
      }
      return 1;
  }
  
  void mbedtls_md5_init( mbedtls_md5_context *ctx )
  {
      mbedtls_zeroize( ctx, sizeof( mbedtls_md5_context ) );
  
      /* Enable HASH clock */
      __HAL_RCC_HASH_CLK_ENABLE();
  
  }
  
  void mbedtls_md5_free( mbedtls_md5_context *ctx )
  {
      if( ctx == NULL )
          return;
      mbedtls_zeroize( ctx, sizeof( mbedtls_md5_context ) );
  }
  
  void mbedtls_md5_clone( mbedtls_md5_context *dst,
                          const mbedtls_md5_context *src )
  {
      *dst = *src;
  }
  
  int mbedtls_md5_starts_ret( mbedtls_md5_context *ctx )
  {
      /* HASH IP initialization */
      if (HAL_HASH_DeInit(&ctx->hhash_md5) != 0) {
          return MBEDTLS_ERR_MD5_HW_ACCEL_FAILED;
      }
  
      /* HASH Configuration */
      ctx->hhash_md5.Init.DataType = HASH_DATATYPE_8B;
      /* clear CR ALGO value */
      HASH->CR &= ~HASH_CR_ALGO_Msk;
      if (HAL_HASH_Init(&ctx->hhash_md5) != 0) {
          return MBEDTLS_ERR_MD5_HW_ACCEL_FAILED;
      }
      if (st_md5_save_hw_context(ctx) != 1) {
          return MBEDTLS_ERR_MD5_HW_ACCEL_FAILED; // Hash busy timeout
      }
  
      return 0;
  }
  
  int mbedtls_md5_process( mbedtls_md5_context *ctx, const unsigned char data[ST_MD5_BLOCK_SIZE] )
  {
      if (st_md5_restore_hw_context(ctx) != 1) {
          return MBEDTLS_ERR_MD5_HW_ACCEL_FAILED; // Hash busy timeout
      }
      if (HAL_HASH_MD5_Accumulate(&ctx->hhash_md5, (uint8_t *)data, ST_MD5_BLOCK_SIZE) != 0) {
          return MBEDTLS_ERR_MD5_HW_ACCEL_FAILED;
      }
      if (st_md5_save_hw_context(ctx) != 1) {
          return MBEDTLS_ERR_MD5_HW_ACCEL_FAILED; // Hash busy timeout
      }
  
      return 0;
  }
  
  int mbedtls_md5_update_ret( mbedtls_md5_context *ctx, const unsigned char *input, size_t ilen )
  {
      size_t currentlen = ilen;
      /* If ilen = 0 : do nothing */
      if (currentlen != 0) {
          if (st_md5_restore_hw_context(ctx) != 1) {
              return MBEDTLS_ERR_MD5_HW_ACCEL_FAILED; // Hash busy timeout
          }
  
          // store mechanism to accumulate ST_MD5_BLOCK_SIZE bytes (512 bits) in the HW
          if (currentlen < (ST_MD5_BLOCK_SIZE - ctx->sbuf_len)) {
              // only buffurize
              memcpy(ctx->sbuf+ctx->sbuf_len, input, currentlen);
              ctx->sbuf_len += currentlen;
          } else {
              // fill buffer and process it
              memcpy(ctx->sbuf + ctx->sbuf_len, input, (ST_MD5_BLOCK_SIZE - ctx->sbuf_len));
              currentlen -= (ST_MD5_BLOCK_SIZE - ctx->sbuf_len);
              mbedtls_md5_process(ctx, ctx->sbuf);
              // Process every input as long as it is %64 bytes, ie 512 bits
              size_t iter = currentlen / ST_MD5_BLOCK_SIZE;
              if (iter !=0) {
                  if (HAL_HASH_MD5_Accumulate(&ctx->hhash_md5, (uint8_t *)(input + ST_MD5_BLOCK_SIZE - ctx->sbuf_len), (iter * ST_MD5_BLOCK_SIZE)) != 0) {
                      return MBEDTLS_ERR_MD5_HW_ACCEL_FAILED;
                  }
              }
              // sbuf is completely accumulated, now copy up to 63 remaining bytes
              ctx->sbuf_len = currentlen % ST_MD5_BLOCK_SIZE;
              if (ctx->sbuf_len !=0) {
                  memcpy(ctx->sbuf, input + ilen - ctx->sbuf_len, ctx->sbuf_len);
              }
          }
  
          if (st_md5_save_hw_context(ctx) != 1) {
              return MBEDTLS_ERR_MD5_HW_ACCEL_FAILED; // Hash busy timeout
          }
      }
  }
  
  int mbedtls_md5_finish_ret( mbedtls_md5_context *ctx, unsigned char output[16] )
  {
      if (st_md5_restore_hw_context(ctx) != 1) {
          return MBEDTLS_ERR_MD5_HW_ACCEL_FAILED; // Hash busy timeout
      }
      /* Last accumulation for extra bytes in sbuf_len */
      /* This sets HW flags in case mbedtls_md5_update has not been called yet */
      if (HAL_HASH_MD5_Accumulate(&ctx->hhash_md5, ctx->sbuf, ctx->sbuf_len) != 0) {
          return MBEDTLS_ERR_MD5_HW_ACCEL_FAILED; // Accumulation error
      }
  
      mbedtls_zeroize( ctx->sbuf, ST_MD5_BLOCK_SIZE);
      ctx->sbuf_len = 0;
      __HAL_HASH_START_DIGEST();
  
      if (HAL_HASH_MD5_Finish(&ctx->hhash_md5, output, 10)) {
          return MBEDTLS_ERR_MD5_HW_ACCEL_FAILED; // Finish error
      }
      if (st_md5_save_hw_context(ctx) != 1) {
          return MBEDTLS_ERR_MD5_HW_ACCEL_FAILED; // Hash busy timeout
      }
  
      return 0;
  }
  
  #endif /* MBEDTLS_MD5_ALT */
  #endif /* MBEDTLS_MD5_C */
  