graphene/Pal/lib/crypto/adapters/mbedtls_adapter.c

/* Copyright (C) 2017 Fortanix, Inc.

   This file is part of Graphene Library OS.

   Graphene Library OS is free software: you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation, either version 3 of the
   License, or (at your option) any later version.

   Graphene Library OS is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include <stdint.h>
#include "pal.h"
#include "pal_crypto.h"
#include "crypto/mbedtls/mbedtls/sha256.h"

int DkSHA256Init(PAL_SHA256_CONTEXT *context)
{
    mbedtls_sha256_init(context);
    mbedtls_sha256_starts(context, 0 /* 0 = use SSH256 */);
    return 0;
}

int DkSHA256Update(PAL_SHA256_CONTEXT *context, const uint8_t *data,
                   PAL_NUM len)
{
    /* For compatibility with other SHA256 providers, don't support
     * large lengths. */
    if (len > UINT32_MAX) {
        return -1;
    }
    mbedtls_sha256_update(context, data, len);
    return 0;
}

int DkSHA256Final(PAL_SHA256_CONTEXT *context, uint8_t *output)
{
    mbedtls_sha256_finish(context, output);
    /* This function is called free, but it doesn't actually free the memory.
     * It zeroes out the context to avoid potentially leaking information
     * about the hash that was just performed. */
    mbedtls_sha256_free(context);
    return 0;
}