/* $OpenBSD: hmac.c,v 1.14 2020/02/26 13:40:09 jsg Exp $ */

/*

 * Copyright (c) 2014 Markus Friedl.  All rights reserved.

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR

 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN

 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF

 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

 */

#include "includes.h"

#include <sys/types.h>

#include <stdlib.h>

#include <string.h>

#include "sshbuf.h"

#include "digest.h"

#include "hmac.h"

struct ssh_hmac_ctx {

  int      alg;

  struct ssh_digest_ctx *ictx;

  struct ssh_digest_ctx *octx;

  struct ssh_digest_ctx *digest;

  u_char      *buf;

  size_t       buf_len;

};

size_t

ssh_hmac_bytes(int alg)

{

  return ssh_digest_bytes(alg);

}

struct ssh_hmac_ctx *

ssh_hmac_start(int alg)

{

  struct ssh_hmac_ctx *ret;

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

    return NULL;

  ret->alg = alg;

  if ((ret->ictx = ssh_digest_start(alg)) == NULL ||

      (ret->octx = ssh_digest_start(alg)) == NULL ||

      (ret->digest = ssh_digest_start(alg)) == NULL)

    goto fail;

  ret->buf_len = ssh_digest_blocksize(ret->ictx);

  if ((ret->buf = calloc(1, ret->buf_len)) == NULL)

    goto fail;

  return ret;

fail:

  ssh_hmac_free(ret);

  return NULL;

}

int

ssh_hmac_init(struct ssh_hmac_ctx *ctx, const void *key, size_t klen)

{

  size_t i;

  /* reset ictx and octx if no is key given */

  if (key != NULL) {

    /* truncate long keys */

    if (klen <= ctx->buf_len)

      memcpy(ctx->buf, key, klen);

    else if (ssh_digest_memory(ctx->alg, key, klen, ctx->buf,

        ctx->buf_len) < 0)

      return -1;

    for (i = 0; i < ctx->buf_len; i++)

      ctx->buf[i] ^= 0x36;

    if (ssh_digest_update(ctx->ictx, ctx->buf, ctx->buf_len) < 0)

      return -1;

    for (i = 0; i < ctx->buf_len; i++)

      ctx->buf[i] ^= 0x36 ^ 0x5c;

    if (ssh_digest_update(ctx->octx, ctx->buf, ctx->buf_len) < 0)

      return -1;

    explicit_bzero(ctx->buf, ctx->buf_len);

  }

  /* start with ictx */

  if (ssh_digest_copy_state(ctx->ictx, ctx->digest) < 0)

    return -1;

  return 0;

}

int

ssh_hmac_update(struct ssh_hmac_ctx *ctx, const void *m, size_t mlen)

{

  return ssh_digest_update(ctx->digest, m, mlen);

}

int

ssh_hmac_update_buffer(struct ssh_hmac_ctx *ctx, const struct sshbuf *b)

{

  return ssh_digest_update_buffer(ctx->digest, b);

}

int

ssh_hmac_final(struct ssh_hmac_ctx *ctx, u_char *d, size_t dlen)

{

  size_t len;

  len = ssh_digest_bytes(ctx->alg);

  if (dlen < len ||

      ssh_digest_final(ctx->digest, ctx->buf, len))

    return -1;

  /* switch to octx */

  if (ssh_digest_copy_state(ctx->octx, ctx->digest) < 0 ||

      ssh_digest_update(ctx->digest, ctx->buf, len) < 0 ||

      ssh_digest_final(ctx->digest, d, dlen) < 0)

    return -1;

  return 0;

}

void

ssh_hmac_free(struct ssh_hmac_ctx *ctx)

{

  if (ctx != NULL) {

    ssh_digest_free(ctx->ictx);

    ssh_digest_free(ctx->octx);

    ssh_digest_free(ctx->digest);

    if (ctx->buf) {

      explicit_bzero(ctx->buf, ctx->buf_len);

      free(ctx->buf);

    }

    freezero(ctx, sizeof(*ctx));

  }

}

#ifdef TEST

/* cc -DTEST hmac.c digest.c buffer.c cleanup.c fatal.c log.c xmalloc.c -lcrypto */

static void

hmac_test(void *key, size_t klen, void *m, size_t mlen, u_char *e, size_t elen)

{

  struct ssh_hmac_ctx *ctx;

  size_t       i;

  u_char       digest[16];

  if ((ctx = ssh_hmac_start(SSH_DIGEST_MD5)) == NULL)

    printf("ssh_hmac_start failed");

  if (ssh_hmac_init(ctx, key, klen) < 0 ||

      ssh_hmac_update(ctx, m, mlen) < 0 ||

      ssh_hmac_final(ctx, digest, sizeof(digest)) < 0)

    printf("ssh_hmac_xxx failed");

  ssh_hmac_free(ctx);

  if (memcmp(e, digest, elen)) {

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

      printf("[%zu] %2.2x %2.2x\n", i, e[i], digest[i]);

    printf("mismatch\n");

  } else

    printf("ok\n");

}

int

main(int argc, char **argv)

{

  /* try test vectors from RFC 2104 */

  u_char key1[16] = {

      0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb,

      0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb };

  u_char *data1 = "Hi There";

  u_char dig1[16] = {

      0x92, 0x94, 0x72, 0x7a, 0x36, 0x38, 0xbb, 0x1c,

      0x13, 0xf4, 0x8e, 0xf8, 0x15, 0x8b, 0xfc, 0x9d };

  u_char *key2 = "Jefe";

  u_char *data2 = "what do ya want for nothing?";

  u_char dig2[16] = {

      0x75, 0x0c, 0x78, 0x3e, 0x6a, 0xb0, 0xb5, 0x03,

      0xea, 0xa8, 0x6e, 0x31, 0x0a, 0x5d, 0xb7, 0x38 };

  u_char key3[16];

  u_char data3[50];

  u_char dig3[16] = {

      0x56, 0xbe, 0x34, 0x52, 0x1d, 0x14, 0x4c, 0x88,

      0xdb, 0xb8, 0xc7, 0x33, 0xf0, 0xe8, 0xb3, 0xf6 };

  memset(key3, 0xaa, sizeof(key3));

  memset(data3, 0xdd, sizeof(data3));

  hmac_test(key1, sizeof(key1), data1, strlen(data1), dig1, sizeof(dig1));

  hmac_test(key2, strlen(key2), data2, strlen(data2), dig2, sizeof(dig2));

  hmac_test(key3, sizeof(key3), data3, sizeof(data3), dig3, sizeof(dig3));

  return 0;

}

#endif