mbed-os/features/mbedtls/targets/TARGET_STM/sha256_alt.c

/*
 *  sha256_alt.c for SHA256 HASH
 *******************************************************************************
 * 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/sha256.h"

#if defined(MBEDTLS_SHA256_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;
}

void mbedtls_sha256_init( mbedtls_sha256_context *ctx )
{
    mbedtls_zeroize( ctx, sizeof( mbedtls_sha256_context ) );

    /* Enable HASH clock */
    __HAL_RCC_HASH_CLK_ENABLE();
}

void mbedtls_sha256_free( mbedtls_sha256_context *ctx )
{
    if( ctx == NULL )
        return;
    /* Force the HASH Periheral Clock Reset */
    __HAL_RCC_HASH_FORCE_RESET();

    /* Release the HASH Periheral Clock Reset */
    __HAL_RCC_HASH_RELEASE_RESET();

    mbedtls_zeroize( ctx, sizeof( mbedtls_sha256_context ) );
}

void mbedtls_sha256_clone( mbedtls_sha256_context *dst,
                         const mbedtls_sha256_context *src )
{
    *dst = *src;
}

void mbedtls_sha256_starts( mbedtls_sha256_context *ctx, int is224 )
{
    /* HASH IP initialization */
    if (HAL_HASH_DeInit(&ctx->hhash_sha256) == HAL_ERROR) {
        // error found to be returned
        return;
    }

    ctx->is224 = is224;
    /* HASH Configuration */
    ctx->hhash_sha256.Init.DataType = HASH_DATATYPE_8B;
    if (HAL_HASH_Init(&ctx->hhash_sha256) == HAL_ERROR) {
        // error found to be returned
        return;
    }
}

void mbedtls_sha256_process( mbedtls_sha256_context *ctx, const unsigned char data[MBEDTLS_SHA256_BLOCK_SIZE] )
{
    if (ctx->is224 == 0) {
        HAL_HASHEx_SHA256_Accumulate(&ctx->hhash_sha256, (uint8_t *) data, MBEDTLS_SHA256_BLOCK_SIZE);
    } else {
        HAL_HASHEx_SHA224_Accumulate(&ctx->hhash_sha256, (uint8_t *) data, MBEDTLS_SHA256_BLOCK_SIZE);
    }
}

void mbedtls_sha256_update( mbedtls_sha256_context *ctx, const unsigned char *input, size_t ilen )
{
    size_t currentlen = ilen;
    // store mechanism to handle MBEDTLS_SHA256_BLOCK_SIZE bytes per MBEDTLS_SHA256_BLOCK_SIZE bytes
    if (currentlen == 0){ // only change HW status is size if 0
        if(ctx->hhash_sha256.Phase == HAL_HASH_PHASE_READY) {
            /* Select the SHA256 or SHA224 mode and reset the HASH processor core, so that the HASH will be ready to compute
             the message digest of a new message */
            if (ctx->is224 == 0) {
                HASH->CR |= HASH_ALGOSELECTION_SHA256 | HASH_CR_INIT;
            } else {
                HASH->CR |= HASH_ALGOSELECTION_SHA224 | HASH_CR_INIT;
            }
        }
        ctx->hhash_sha256.Phase = HAL_HASH_PHASE_PROCESS;
    } else if (currentlen < (MBEDTLS_SHA256_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, (MBEDTLS_SHA256_BLOCK_SIZE-ctx->sbuf_len));
        currentlen -= (MBEDTLS_SHA256_BLOCK_SIZE - ctx->sbuf_len);
        mbedtls_sha256_process(ctx, ctx->sbuf);
        // now process every input as long as it is %4 bytes
        size_t iter = currentlen / 4;
        if (ctx->is224 == 0) {
            HAL_HASHEx_SHA256_Accumulate(&ctx->hhash_sha256, (uint8_t *)(input + MBEDTLS_SHA256_BLOCK_SIZE - ctx->sbuf_len),  (iter * 4));
        } else {
            HAL_HASHEx_SHA224_Accumulate(&ctx->hhash_sha256, (uint8_t *)(input + MBEDTLS_SHA256_BLOCK_SIZE - ctx->sbuf_len),  (iter * 4));
        }
        // sbuf is now fully accumulated, now copy 1 / 2 or 3 remaining bytes
        ctx->sbuf_len = currentlen % 4;
        if (ctx->sbuf_len !=0) {
            memcpy(ctx->sbuf, input + iter, ctx->sbuf_len);
        }
    }
}

void mbedtls_sha256_finish( mbedtls_sha256_context *ctx, unsigned char output[32] )
{
    if (ctx->sbuf_len > 0) {
        if (ctx->is224 == 0) {
            HAL_HASHEx_SHA256_Accumulate(&ctx->hhash_sha256, ctx->sbuf, ctx->sbuf_len);
        } else {
            HAL_HASHEx_SHA224_Accumulate(&ctx->hhash_sha256, ctx->sbuf, ctx->sbuf_len);
        }
    }
    mbedtls_zeroize(ctx->sbuf, MBEDTLS_SHA256_BLOCK_SIZE);
    ctx->sbuf_len = 0;
    __HAL_HASH_START_DIGEST();
        
    if (ctx->is224 == 0)
        HAL_HASHEx_SHA256_Finish(&ctx->hhash_sha256, output, 10);
    else
        HAL_HASHEx_SHA224_Finish(&ctx->hhash_sha256, output, 10);
}

#endif /*MBEDTLS_SHA256_ALT*/