hmac.c

/**
 * Copyright (c) 2013-2014 Tomas Dzetkulic
 * Copyright (c) 2013-2014 Pavol Rusnak
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
 * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

#include <string.h>

#include "hmac.h"
#include "memzero.h"
#include "options.h"

void hmac_sha256_Init(HMAC_SHA256_CTX *hctx, const uint8_t *key,
                      const uint32_t keylen) {
  static CONFIDENTIAL uint8_t i_key_pad[SHA256_BLOCK_LENGTH];
  memzero(i_key_pad, SHA256_BLOCK_LENGTH);
  if (keylen > SHA256_BLOCK_LENGTH) {
    sha256_Raw(key, keylen, i_key_pad);
  } else {
    memcpy(i_key_pad, key, keylen);
  }
  for (int i = 0; i < SHA256_BLOCK_LENGTH; i++) {
    hctx->o_key_pad[i] = i_key_pad[i] ^ 0x5c;
    i_key_pad[i] ^= 0x36;
  }
  sha256_Init(&(hctx->ctx));
  sha256_Update(&(hctx->ctx), i_key_pad, SHA256_BLOCK_LENGTH);
  memzero(i_key_pad, sizeof(i_key_pad));
}

void hmac_sha256_Update(HMAC_SHA256_CTX *hctx, const uint8_t *msg,
                        const uint32_t msglen) {
  sha256_Update(&(hctx->ctx), msg, msglen);
}

void hmac_sha256_Final(HMAC_SHA256_CTX *hctx, uint8_t *hmac) {
  sha256_Final(&(hctx->ctx), hmac);
  sha256_Init(&(hctx->ctx));
  sha256_Update(&(hctx->ctx), hctx->o_key_pad, SHA256_BLOCK_LENGTH);
  sha256_Update(&(hctx->ctx), hmac, SHA256_DIGEST_LENGTH);
  sha256_Final(&(hctx->ctx), hmac);
  memzero(hctx, sizeof(HMAC_SHA256_CTX));
}

void hmac_sha256(const uint8_t *key, const uint32_t keylen, const uint8_t *msg,
                 const uint32_t msglen, uint8_t *hmac) {
  static CONFIDENTIAL HMAC_SHA256_CTX hctx;
  hmac_sha256_Init(&hctx, key, keylen);
  hmac_sha256_Update(&hctx, msg, msglen);
  hmac_sha256_Final(&hctx, hmac);
}

void hmac_sha256_prepare(const uint8_t *key, const uint32_t keylen,
                         uint32_t *opad_digest, uint32_t *ipad_digest) {
  static CONFIDENTIAL uint32_t key_pad[SHA256_BLOCK_LENGTH / sizeof(uint32_t)];

  memzero(key_pad, sizeof(key_pad));
  if (keylen > SHA256_BLOCK_LENGTH) {
    static CONFIDENTIAL SHA256_CTX context;
    sha256_Init(&context);
    sha256_Update(&context, key, keylen);
    sha256_Final(&context, (uint8_t *)key_pad);
  } else {
    memcpy(key_pad, key, keylen);
  }

  /* compute o_key_pad and its digest */
  for (int i = 0; i < SHA256_BLOCK_LENGTH / (int)sizeof(uint32_t); i++) {
    uint32_t data;
#if BYTE_ORDER == LITTLE_ENDIAN
    REVERSE32(key_pad[i], data);
#else
    data = key_pad[i];
#endif
    key_pad[i] = data ^ 0x5c5c5c5c;
  }
  sha256_Transform(sha256_initial_hash_value, key_pad, opad_digest);

  /* convert o_key_pad to i_key_pad and compute its digest */
  for (int i = 0; i < SHA256_BLOCK_LENGTH / (int)sizeof(uint32_t); i++) {
    key_pad[i] = key_pad[i] ^ 0x5c5c5c5c ^ 0x36363636;
  }
  sha256_Transform(sha256_initial_hash_value, key_pad, ipad_digest);
  memzero(key_pad, sizeof(key_pad));
}

void hmac_sha512_Init(HMAC_SHA512_CTX *hctx, const uint8_t *key,
                      const uint32_t keylen) {
  static CONFIDENTIAL uint8_t i_key_pad[SHA512_BLOCK_LENGTH];
  memzero(i_key_pad, SHA512_BLOCK_LENGTH);
  if (keylen > SHA512_BLOCK_LENGTH) {
    sha512_Raw(key, keylen, i_key_pad);
  } else {
    memcpy(i_key_pad, key, keylen);
  }
  for (int i = 0; i < SHA512_BLOCK_LENGTH; i++) {
    hctx->o_key_pad[i] = i_key_pad[i] ^ 0x5c;
    i_key_pad[i] ^= 0x36;
  }
  sha512_Init(&(hctx->ctx));
  sha512_Update(&(hctx->ctx), i_key_pad, SHA512_BLOCK_LENGTH);
  memzero(i_key_pad, sizeof(i_key_pad));
}

void hmac_sha512_Update(HMAC_SHA512_CTX *hctx, const uint8_t *msg,
                        const uint32_t msglen) {
  sha512_Update(&(hctx->ctx), msg, msglen);
}

void hmac_sha512_Final(HMAC_SHA512_CTX *hctx, uint8_t *hmac) {
  sha512_Final(&(hctx->ctx), hmac);
  sha512_Init(&(hctx->ctx));
  sha512_Update(&(hctx->ctx), hctx->o_key_pad, SHA512_BLOCK_LENGTH);
  sha512_Update(&(hctx->ctx), hmac, SHA512_DIGEST_LENGTH);
  sha512_Final(&(hctx->ctx), hmac);
  memzero(hctx, sizeof(HMAC_SHA512_CTX));
}

void hmac_sha512(const uint8_t *key, const uint32_t keylen, const uint8_t *msg,
                 const uint32_t msglen, uint8_t *hmac) {
  HMAC_SHA512_CTX hctx;
  hmac_sha512_Init(&hctx, key, keylen);
  hmac_sha512_Update(&hctx, msg, msglen);
  hmac_sha512_Final(&hctx, hmac);
}

void hmac_sha512_prepare(const uint8_t *key, const uint32_t keylen,
                         uint64_t *opad_digest, uint64_t *ipad_digest) {
  static CONFIDENTIAL uint64_t key_pad[SHA512_BLOCK_LENGTH / sizeof(uint64_t)];

  memzero(key_pad, sizeof(key_pad));
  if (keylen > SHA512_BLOCK_LENGTH) {
    static CONFIDENTIAL SHA512_CTX context;
    sha512_Init(&context);
    sha512_Update(&context, key, keylen);
    sha512_Final(&context, (uint8_t *)key_pad);
  } else {
    memcpy(key_pad, key, keylen);
  }

  /* compute o_key_pad and its digest */
  for (int i = 0; i < SHA512_BLOCK_LENGTH / (int)sizeof(uint64_t); i++) {
    uint64_t data;
#if BYTE_ORDER == LITTLE_ENDIAN
    REVERSE64(key_pad[i], data);
#else
    data = key_pad[i];
#endif
    key_pad[i] = data ^ 0x5c5c5c5c5c5c5c5c;
  }
  sha512_Transform(sha512_initial_hash_value, key_pad, opad_digest);

  /* convert o_key_pad to i_key_pad and compute its digest */
  for (int i = 0; i < SHA512_BLOCK_LENGTH / (int)sizeof(uint64_t); i++) {
    key_pad[i] = key_pad[i] ^ 0x5c5c5c5c5c5c5c5c ^ 0x3636363636363636;
  }
  sha512_Transform(sha512_initial_hash_value, key_pad, ipad_digest);
  memzero(key_pad, sizeof(key_pad));
}