hmacmd5.c

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/* SPDX-FileCopyrightText: 2023 Greenbone AG
 * SPDX-FileCopyrightText: 1996-2000 Luke Kenneth Casson Leighton
 * SPDX-FileCopyrightText: 1992-2000 Andrew Tridgell
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

 
#include "hmacmd5.h"
 
#include <string.h> /* for memset */

void
hmac_md5_init_limK_to_64 (const uchar *key, int key_len, HMACMD5Context *ctx)
{
  int i;
 
  /* if key is longer than 64 bytes truncate it */
  if (key_len > 64)
    {
      key_len = 64;
    }
 
  /* start out by storing key in pads */
  ZERO_STRUCT (ctx->k_ipad);
  ZERO_STRUCT (ctx->k_opad);
  memcpy (ctx->k_ipad, key, key_len);
  memcpy (ctx->k_opad, key, key_len);
 
  /* XOR key with ipad and opad values */
  for (i = 0; i < 64; i++)
    {
      ctx->k_ipad[i] ^= 0x36;
      ctx->k_opad[i] ^= 0x5c;
    }
 
  MD5Init (&ctx->ctx);
  MD5Update (&ctx->ctx, ctx->k_ipad, 64);
}

void
hmac_md5_update (const uchar *text, int text_len, HMACMD5Context *ctx)
{
  MD5Update (&ctx->ctx, text, text_len); /* then text of datagram */
}

void
hmac_md5_final (uchar *digest, HMACMD5Context *ctx)
 
{
  struct MD5Context ctx_o;
 
  MD5Final (digest, &ctx->ctx);
 
  MD5Init (&ctx_o);
  MD5Update (&ctx_o, ctx->k_opad, 64);
  MD5Update (&ctx_o, digest, 16);
  MD5Final (digest, &ctx_o);
}

void
hmac_md5 (uchar key[16], uchar *data, int data_len, uchar *digest)
{
  HMACMD5Context ctx;
  hmac_md5_init_limK_to_64 (key, 16, &ctx);
  if (data_len != 0)
    {
      hmac_md5_update (data, data_len, &ctx);
    }
  hmac_md5_final (digest, &ctx);
}