/*

 * Copyright (c) 2014 Ted Unangst <tedu@openbsd.org>

 * Copyright (c) 1997 Niels Provos <provos@umich.edu>

 *

 * 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.

 */

/* This password hashing algorithm was designed by David Mazieres

 * <dm@lcs.mit.edu> and works as follows:

 *

 * 1. state := InitState ()

 * 2. state := ExpandKey (state, salt, password)

 * 3. REPEAT rounds:

 *      state := ExpandKey (state, 0, password)

 *  state := ExpandKey (state, 0, salt)

 * 4. ctext := "OrpheanBeholderScryDoubt"

 * 5. REPEAT 64:

 *  ctext := Encrypt_ECB (state, ctext);

 * 6. RETURN Concatenate (salt, ctext);

 *

 */

#include "config.h"

#include <sys/types.h>

#include "openbsd-blowfish.h"

#include <ctype.h>

#include <errno.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

/* This implementation is adaptable to current computing power.

 * You can have up to 2^31 rounds which should be enough for some

 * time to come.

 */

#define BCRYPT_VERSION '2'

#define BCRYPT_MAXSALT 16  /* Precomputation is just so nice */

#define BCRYPT_WORDS 6    /* Ciphertext words */

#define BCRYPT_MINLOGROUNDS 4  /* we have log2(rounds) in salt */

#define BCRYPT_SALTSPACE  (7 + (BCRYPT_MAXSALT * 4 + 2) / 3 + 1)

#define BCRYPT_HASHSPACE  61

static int encode_base64(char *, const u_int8_t *, size_t);

static int decode_base64(u_int8_t *, size_t, const char *);

/*

 * the core bcrypt function

 */

int

bcrypt_hashpass(const char *key, const char *salt, char *encrypted,

    size_t encryptedlen)

{

  blf_ctx state;

  u_int32_t rounds, i, k;

  u_int16_t j;

  size_t key_len;

  u_int8_t salt_len, logr, minor;

  u_int8_t ciphertext[4 * BCRYPT_WORDS] = "OrpheanBeholderScryDoubt";

  u_int8_t csalt[BCRYPT_MAXSALT];

  u_int32_t cdata[BCRYPT_WORDS];

  if (encryptedlen < BCRYPT_HASHSPACE)

    goto inval;

  /* Check and discard "$" identifier */

  if (salt[0] != '$')

    goto inval;

  salt += 1;

  if (salt[0] != BCRYPT_VERSION)

    goto inval;

  /* Check for minor versions */

  switch ((minor = salt[1])) {

  case 'a':

    key_len = (u_int8_t)(strlen(key) + 1);

    break;

  case 'b':

    /* strlen() returns a size_t, but the function calls

     * below result in implicit casts to a narrower integer

     * type, so cap key_len at the actual maximum supported

     * length here to avoid integer wraparound */

    key_len = strlen(key);

    if (key_len > 72)

      key_len = 72;

    key_len++; /* include the NUL */

    break;

  case 'y':

    /* PHP-specific version; see:

     *  https://www.php.net/manual/en/function.password-hash.php

     */

    key_len = (u_int8_t)(strlen(key) + 1);

    break;

  default:

     goto inval;

  }

  if (salt[2] != '$')

    goto inval;

  /* Discard version + "$" identifier */

  salt += 3;

  /* Check and parse num rounds */

  if (!isdigit((unsigned char)salt[0]) ||

      !isdigit((unsigned char)salt[1]) || salt[2] != '$')

    goto inval;

  logr = (salt[1] - '0') + ((salt[0] - '0') * 10);

  if (logr < BCRYPT_MINLOGROUNDS || logr > 31)

    goto inval;

  /* Computer power doesn't increase linearly, 2^x should be fine */

  rounds = 1U << logr;

  /* Discard num rounds + "$" identifier */

  salt += 3;

  if (strlen(salt) * 3 / 4 < BCRYPT_MAXSALT)

    goto inval;

  /* We dont want the base64 salt but the raw data */

  if (decode_base64(csalt, BCRYPT_MAXSALT, salt))

    goto inval;

  salt_len = BCRYPT_MAXSALT;

  /* Setting up S-Boxes and Subkeys */

  Blowfish_initstate(&state);

  Blowfish_expandstate(&state, csalt, salt_len,

      (u_int8_t *) key, key_len);

  for (k = 0; k < rounds; k++) {

    Blowfish_expand0state(&state, (u_int8_t *) key, key_len);

    Blowfish_expand0state(&state, csalt, salt_len);

  }

  /* This can be precomputed later */

  j = 0;

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

    cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_WORDS, &j);

  /* Now do the encryption */

  for (k = 0; k < 64; k++)

    blf_enc(&state, cdata, BCRYPT_WORDS / 2);

  for (i = 0; i < BCRYPT_WORDS; i++) {

    ciphertext[4 * i + 3] = cdata[i] & 0xff;

    cdata[i] = cdata[i] >> 8;

    ciphertext[4 * i + 2] = cdata[i] & 0xff;

    cdata[i] = cdata[i] >> 8;

    ciphertext[4 * i + 1] = cdata[i] & 0xff;

    cdata[i] = cdata[i] >> 8;

    ciphertext[4 * i + 0] = cdata[i] & 0xff;

  }

  snprintf(encrypted, 8, "$2%c$%2.2u$", minor, logr);

  encode_base64(encrypted + 7, csalt, BCRYPT_MAXSALT);

  encode_base64(encrypted + 7 + 22, ciphertext, 4 * BCRYPT_WORDS - 1);

#if defined(HAVE_EXPLICIT_BZERO)

  explicit_bzero(&state, sizeof(state));

  explicit_bzero(ciphertext, sizeof(ciphertext));

  explicit_bzero(csalt, sizeof(csalt));

  explicit_bzero(cdata, sizeof(cdata));

#elif defined(HAVE_MEMSET_S)

  (void) memset_s(&state, sizeof(state), '\0', sizeof(state));

  (void) memset_s(ciphertext, sizeof(ciphertext), '\0', sizeof(ciphertext));

  (void) memset_s(csalt, sizeof(csalt), '\0', sizeof(csalt));

  (void) memset_s(cdata, sizeof(cdata), '\0', sizeof(cdata));

#else

  memset(&state, '\0', sizeof(state));

  memset(ciphertext, '\0', sizeof(ciphertext));

  memset(csalt, '\0', sizeof(csalt));

  memset(cdata, '\0', sizeof(cdata));

#endif

  return 0;

inval:

  errno = EINVAL;

  return -1;

}

/*

 * internal utilities

 */

static const u_int8_t Base64Code[] =

"./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

static const u_int8_t index_64[128] = {

  255, 255, 255, 255, 255, 255, 255, 255, 255, 255,

  255, 255, 255, 255, 255, 255, 255, 255, 255, 255,

  255, 255, 255, 255, 255, 255, 255, 255, 255, 255,

  255, 255, 255, 255, 255, 255, 255, 255, 255, 255,

  255, 255, 255, 255, 255, 255, 0, 1, 54, 55,

  56, 57, 58, 59, 60, 61, 62, 63, 255, 255,

  255, 255, 255, 255, 255, 2, 3, 4, 5, 6,

  7, 8, 9, 10, 11, 12, 13, 14, 15, 16,

  17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,

  255, 255, 255, 255, 255, 255, 28, 29, 30,

  31, 32, 33, 34, 35, 36, 37, 38, 39, 40,

  41, 42, 43, 44, 45, 46, 47, 48, 49, 50,

  51, 52, 53, 255, 255, 255, 255, 255

};

#define CHAR64(c)  ( (c) > 127 ? 255 : index_64[(c)])

/*

 * read buflen (after decoding) bytes of data from b64data

 */

static int

decode_base64(u_int8_t *buffer, size_t len, const char *b64data)

{

  u_int8_t *bp = buffer;

  const u_int8_t *p = (const unsigned char *) b64data;

  u_int8_t c1, c2, c3, c4;

  while (bp < buffer + len) {

    c1 = CHAR64(*p);

    /* Invalid data */

    if (c1 == 255)

      return -1;

    c2 = CHAR64(*(p + 1));

    if (c2 == 255)

      return -1;

    *bp++ = (c1 << 2) | ((c2 & 0x30) >> 4);

    if (bp >= buffer + len)

      break;

    c3 = CHAR64(*(p + 2));

    if (c3 == 255)

      return -1;

    *bp++ = ((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2);

    if (bp >= buffer + len)

      break;

    c4 = CHAR64(*(p + 3));

    if (c4 == 255)

      return -1;

    *bp++ = ((c3 & 0x03) << 6) | c4;

    p += 4;

  }

  return 0;

}

/*

 * Turn len bytes of data into base64 encoded data.

 * This works without = padding.

 */

int

encode_base64(char *b64buffer, const u_int8_t *data, size_t len)

{

  u_int8_t *bp = (unsigned char *) b64buffer;

  const u_int8_t *p = data;

  u_int8_t c1, c2;

  while (p < data + len) {

    c1 = *p++;

    *bp++ = Base64Code[(c1 >> 2)];

    c1 = (c1 & 0x03) << 4;

    if (p >= data + len) {

      *bp++ = Base64Code[c1];

      break;

    }

    c2 = *p++;

    c1 |= (c2 >> 4) & 0x0f;

    *bp++ = Base64Code[c1];

    c1 = (c2 & 0x0f) << 2;

    if (p >= data + len) {

      *bp++ = Base64Code[c1];

      break;

    }

    c2 = *p++;

    c1 |= (c2 >> 6) & 0x03;

    *bp++ = Base64Code[c1];

    *bp++ = Base64Code[c2 & 0x3f];

  }

  *bp = '\0';

  return 0;

}