/* $OpenBSD: hmac.c,v 1.28 2022/05/05 18:29:34 tb Exp $ */

/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)

 * All rights reserved.

 *

 * This package is an SSL implementation written

 * by Eric Young (eay@cryptsoft.com).

 * The implementation was written so as to conform with Netscapes SSL.

 *

 * This library is free for commercial and non-commercial use as long as

 * the following conditions are aheared to.  The following conditions

 * apply to all code found in this distribution, be it the RC4, RSA,

 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation

 * included with this distribution is covered by the same copyright terms

 * except that the holder is Tim Hudson (tjh@cryptsoft.com).

 *

 * Copyright remains Eric Young's, and as such any Copyright notices in

 * the code are not to be removed.

 * If this package is used in a product, Eric Young should be given attribution

 * as the author of the parts of the library used.

 * This can be in the form of a textual message at program startup or

 * in documentation (online or textual) provided with the package.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. All advertising materials mentioning features or use of this software

 *    must display the following acknowledgement:

 *    "This product includes cryptographic software written by

 *     Eric Young (eay@cryptsoft.com)"

 *    The word 'cryptographic' can be left out if the rouines from the library

 *    being used are not cryptographic related :-).

 * 4. If you include any Windows specific code (or a derivative thereof) from

 *    the apps directory (application code) you must include an acknowledgement:

 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"

 *

 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 *

 * The licence and distribution terms for any publically available version or

 * derivative of this code cannot be changed.  i.e. this code cannot simply be

 * copied and put under another distribution licence

 * [including the GNU Public Licence.]

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <openssl/err.h>

#include <openssl/hmac.h>

#include "evp_locl.h"

#include "hmac_local.h"

int

HMAC_Init_ex(HMAC_CTX *ctx, const void *key, int len, const EVP_MD *md,

    ENGINE *impl)

{

  int i, j, reset = 0;

  unsigned char pad[HMAC_MAX_MD_CBLOCK];

  /* If we are changing MD then we must have a key */

  if (md != NULL && md != ctx->md && (key == NULL || len < 0))

    return 0;

  if (md != NULL) {

    reset = 1;

    ctx->md = md;

  } else if (ctx->md != NULL)

    md = ctx->md;

  else

    return 0;

  if (key != NULL) {

    reset = 1;

    j = EVP_MD_block_size(md);

    if ((size_t)j > sizeof(ctx->key)) {

      EVPerror(EVP_R_BAD_BLOCK_LENGTH);

      goto err;

    }

    if (j < len) {

      if (!EVP_DigestInit_ex(&ctx->md_ctx, md, impl))

        goto err;

      if (!EVP_DigestUpdate(&ctx->md_ctx, key, len))

        goto err;

      if (!EVP_DigestFinal_ex(&(ctx->md_ctx), ctx->key,

          &ctx->key_length))

        goto err;

    } else {

      if (len < 0 || (size_t)len > sizeof(ctx->key)) {

        EVPerror(EVP_R_BAD_KEY_LENGTH);

        goto err;

      }

      memcpy(ctx->key, key, len);

      ctx->key_length = len;

    }

    if (ctx->key_length != HMAC_MAX_MD_CBLOCK)

      memset(&ctx->key[ctx->key_length], 0,

          HMAC_MAX_MD_CBLOCK - ctx->key_length);

  }

  if (reset) {

    for (i = 0; i < HMAC_MAX_MD_CBLOCK; i++)

      pad[i] = 0x36 ^ ctx->key[i];

    if (!EVP_DigestInit_ex(&ctx->i_ctx, md, impl))

      goto err;

    if (!EVP_DigestUpdate(&ctx->i_ctx, pad, EVP_MD_block_size(md)))

      goto err;

    for (i = 0; i < HMAC_MAX_MD_CBLOCK; i++)

      pad[i] = 0x5c ^ ctx->key[i];

    if (!EVP_DigestInit_ex(&ctx->o_ctx, md, impl))

      goto err;

    if (!EVP_DigestUpdate(&ctx->o_ctx, pad, EVP_MD_block_size(md)))

      goto err;

  }

  if (!EVP_MD_CTX_copy_ex(&ctx->md_ctx, &ctx->i_ctx))

    goto err;

  return 1;

err:

  return 0;

}

int

HMAC_Init(HMAC_CTX *ctx, const void *key, int len, const EVP_MD *md)

{

  if (key && md)

    HMAC_CTX_init(ctx);

  return HMAC_Init_ex(ctx, key, len, md, NULL);

}

int

HMAC_Update(HMAC_CTX *ctx, const unsigned char *data, size_t len)

{

  if (ctx->md == NULL)

    return 0;

  return EVP_DigestUpdate(&ctx->md_ctx, data, len);

}

int

HMAC_Final(HMAC_CTX *ctx, unsigned char *md, unsigned int *len)

{

  unsigned int i;

  unsigned char buf[EVP_MAX_MD_SIZE];

  if (ctx->md == NULL)

    goto err;

  if (!EVP_DigestFinal_ex(&ctx->md_ctx, buf, &i))

    goto err;

  if (!EVP_MD_CTX_copy_ex(&ctx->md_ctx, &ctx->o_ctx))

    goto err;

  if (!EVP_DigestUpdate(&ctx->md_ctx, buf, i))

    goto err;

  if (!EVP_DigestFinal_ex(&ctx->md_ctx, md, len))

    goto err;

  return 1;

err:

  return 0;

}

HMAC_CTX *

HMAC_CTX_new(void)

{

  HMAC_CTX *ctx;

  if ((ctx = calloc(1, sizeof(*ctx))) == NULL)

    return NULL;

  HMAC_CTX_init(ctx);

  return ctx;

}

void

HMAC_CTX_free(HMAC_CTX *ctx)

{

  if (ctx == NULL)

    return;

  HMAC_CTX_cleanup(ctx);

  free(ctx);

}

int

HMAC_CTX_reset(HMAC_CTX *ctx)

{

  HMAC_CTX_cleanup(ctx);

  HMAC_CTX_init(ctx);

  return 1;

}

void

HMAC_CTX_init(HMAC_CTX *ctx)

{

  EVP_MD_CTX_init(&ctx->i_ctx);

  EVP_MD_CTX_init(&ctx->o_ctx);

  EVP_MD_CTX_init(&ctx->md_ctx);

  ctx->md = NULL;

}

int

HMAC_CTX_copy(HMAC_CTX *dctx, HMAC_CTX *sctx)

{

  if (!EVP_MD_CTX_copy(&dctx->i_ctx, &sctx->i_ctx))

    goto err;

  if (!EVP_MD_CTX_copy(&dctx->o_ctx, &sctx->o_ctx))

    goto err;

  if (!EVP_MD_CTX_copy(&dctx->md_ctx, &sctx->md_ctx))

    goto err;

  memcpy(dctx->key, sctx->key, HMAC_MAX_MD_CBLOCK);

  dctx->key_length = sctx->key_length;

  dctx->md = sctx->md;

  return 1;

err:

  return 0;

}

void

HMAC_CTX_cleanup(HMAC_CTX *ctx)

{

  EVP_MD_CTX_cleanup(&ctx->i_ctx);

  EVP_MD_CTX_cleanup(&ctx->o_ctx);

  EVP_MD_CTX_cleanup(&ctx->md_ctx);

  explicit_bzero(ctx, sizeof(*ctx));

}

void

HMAC_CTX_set_flags(HMAC_CTX *ctx, unsigned long flags)

{

  EVP_MD_CTX_set_flags(&ctx->i_ctx, flags);

  EVP_MD_CTX_set_flags(&ctx->o_ctx, flags);

  EVP_MD_CTX_set_flags(&ctx->md_ctx, flags);

}

const EVP_MD *

HMAC_CTX_get_md(const HMAC_CTX *ctx)

{

  return ctx->md;

}

unsigned char *

HMAC(const EVP_MD *evp_md, const void *key, int key_len, const unsigned char *d,

    size_t n, unsigned char *md, unsigned int *md_len)

{

  HMAC_CTX c;

  static unsigned char m[EVP_MAX_MD_SIZE];

  const unsigned char dummy_key[1] = { 0 };

  if (md == NULL)

    md = m;

  if (key == NULL) {

    key = dummy_key;

    key_len = 0;

  }

  HMAC_CTX_init(&c);

  if (!HMAC_Init_ex(&c, key, key_len, evp_md, NULL))

    goto err;

  if (!HMAC_Update(&c, d, n))

    goto err;

  if (!HMAC_Final(&c, md, md_len))

    goto err;

  HMAC_CTX_cleanup(&c);

  return md;

err:

  HMAC_CTX_cleanup(&c);

  return NULL;

}