/*

 * crypto_openssl.c - Crypto wrapper (openssl version)

 */

/*

 *  Copyright (C) 2011 Gernot Tenchio

 *  Copyright (C) 2019 Christian Beier

 *

 *  This is free software; you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation; either version 2 of the License, or

 *  (at your option) any later version.

 *

 *  This software is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License for more details.

 *

 *  You should have received a copy of the GNU General Public License

 *  along with this software; if not, write to the Free Software

 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,

 *  USA.

 */

#include <string.h>

#include <openssl/sha.h>

#include <openssl/md5.h>

#include <openssl/dh.h>

#include <openssl/evp.h>

#include <openssl/rand.h>

#if (OPENSSL_VERSION_NUMBER >= 0x30000000L)

#include <openssl/provider.h>

#endif

#include "crypto.h"

static unsigned char reverseByte(unsigned char b) {

   b = (b & 0xF0) >> 4 | (b & 0x0F) << 4;

   b = (b & 0xCC) >> 2 | (b & 0x33) << 2;

   b = (b & 0xAA) >> 1 | (b & 0x55) << 1;

   return b;

}

int hash_md5(void *out, const void *in, const size_t in_len)

{

    MD5_CTX md5;

    if(!MD5_Init(&md5))

  return 0;

    if(!MD5_Update(&md5, in, in_len))

  return 0;

    if(!MD5_Final(out, &md5))

  return 0;

    return 1;

}

#ifdef LIBVNCSERVER_WITH_WEBSOCKETS

int hash_sha1(void *out, const void *in, const size_t in_len)

{

    SHA_CTX sha1;

    if(!SHA1_Init(&sha1))

  return 0;

    if(!SHA1_Update(&sha1, in, in_len))

  return 0;

    if(!SHA1_Final(out, &sha1))

  return 0;

    return 1;

}

#endif /* LIBVNCSERVER_WITH_WEBSOCKETS */

void random_bytes(void *out, size_t len)

{

    RAND_bytes(out, len);

}

int encrypt_rfbdes(void *out, int *out_len, const unsigned char key[8], const void *in, const size_t in_len)

{

    int result = 0;

    EVP_CIPHER_CTX *des = NULL;

    unsigned char mungedkey[8];

    int i;

#if (OPENSSL_VERSION_NUMBER >= 0x30000000L)

    OSSL_PROVIDER *providerLegacy = NULL;

    OSSL_PROVIDER *providerDefault = NULL;

#endif

    for (i = 0; i < 8; i++)

      mungedkey[i] = reverseByte(key[i]);

#if (OPENSSL_VERSION_NUMBER >= 0x30000000L)

    /* Load Multiple providers into the default (NULL) library context */

    if (!(providerLegacy = OSSL_PROVIDER_load(NULL, "legacy")))

      goto out;

    if (!(providerDefault = OSSL_PROVIDER_load(NULL, "default")))

      goto out;

#endif

    if(!(des = EVP_CIPHER_CTX_new()))

  goto out;

    if(!EVP_EncryptInit_ex(des, EVP_des_ecb(), NULL, mungedkey, NULL))

  goto out;

    if(!EVP_EncryptUpdate(des, out, out_len, in, in_len))

  goto out;

    result = 1;

 out:

    if (des)

      EVP_CIPHER_CTX_free(des);

#if (OPENSSL_VERSION_NUMBER >= 0x30000000L)

    if (providerLegacy)

      OSSL_PROVIDER_unload(providerLegacy);

    if (providerDefault)

      OSSL_PROVIDER_unload(providerDefault);

#endif

    return result;

}

int decrypt_rfbdes(void *out, int *out_len, const unsigned char key[8], const void *in, const size_t in_len)

{

    int result = 0;

    EVP_CIPHER_CTX *des = NULL;

    unsigned char mungedkey[8];

    int i;

#if (OPENSSL_VERSION_NUMBER >= 0x30000000L)

    OSSL_PROVIDER *providerLegacy = NULL;

    OSSL_PROVIDER *providerDefault = NULL;

#endif

    for (i = 0; i < 8; i++)

      mungedkey[i] = reverseByte(key[i]);

#if (OPENSSL_VERSION_NUMBER >= 0x30000000L)

    /* Load Multiple providers into the default (NULL) library context */

    if (!(providerLegacy = OSSL_PROVIDER_load(NULL, "legacy")))

  goto out;

    if (!(providerDefault = OSSL_PROVIDER_load(NULL, "default")))

  goto out;

#endif

    if(!(des = EVP_CIPHER_CTX_new()))

  goto out;

    if(!EVP_DecryptInit_ex(des, EVP_des_ecb(), NULL, mungedkey, NULL))

  goto out;

    if(!EVP_CIPHER_CTX_set_padding(des, 0))

  goto out;

    if(!EVP_DecryptUpdate(des, out, out_len, in, in_len))

  goto out;

    result = 1;

 out:

    if (des)

  EVP_CIPHER_CTX_free(des);

#if (OPENSSL_VERSION_NUMBER >= 0x30000000L)

    if (providerLegacy)

  OSSL_PROVIDER_unload(providerLegacy);

    if (providerDefault)

  OSSL_PROVIDER_unload(providerDefault);

#endif

    return result;

}

int encrypt_aes128ecb(void *out, int *out_len, const unsigned char key[16], const void *in, const size_t in_len)

{

    int result = 0;

    EVP_CIPHER_CTX *aes;

    if(!(aes = EVP_CIPHER_CTX_new()))

  goto out;

    EVP_CIPHER_CTX_set_padding(aes, 0);

    if(!EVP_EncryptInit_ex(aes, EVP_aes_128_ecb(), NULL, key, NULL))

  goto out;

    if(!EVP_EncryptUpdate(aes, out, out_len, in, in_len))

  goto out;

    result = 1;

 out:

    EVP_CIPHER_CTX_free(aes);

    return result;

}

static void pad_leading_zeros(uint8_t *out, const size_t current_len, const size_t expected_len) {

    if (current_len >= expected_len || expected_len < 1)

        return;

    size_t diff = expected_len - current_len;

    memmove(out + diff, out, current_len);

    memset(out, 0, diff);

}

int dh_generate_keypair(uint8_t *priv_out, uint8_t *pub_out, const uint8_t *gen, const size_t gen_len, const uint8_t *prime, const size_t keylen)

{

    int result = 0;

    DH *dh;

#if OPENSSL_VERSION_NUMBER >= 0x10100000L || \

  (defined (LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER >= 0x30500000)

    const BIGNUM *pub_key = NULL;

    const BIGNUM *priv_key = NULL;

#endif

    if(!(dh = DH_new()))

  goto out;

#if OPENSSL_VERSION_NUMBER < 0x10100000L || \

  (defined (LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x30500000)

    dh->p = BN_bin2bn(prime, keylen, NULL);

    dh->g = BN_bin2bn(gen, gen_len, NULL);

#else

    if(!DH_set0_pqg(dh, BN_bin2bn(prime, keylen, NULL), NULL, BN_bin2bn(gen, gen_len, NULL)))

  goto out;

#endif

    if(!DH_generate_key(dh))

  goto out;

#if OPENSSL_VERSION_NUMBER < 0x10100000L || \

  (defined (LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x30500000)

    if(BN_bn2bin(dh->priv_key, priv_out) == 0)

  goto out;

    if(BN_bn2bin(dh->pub_key, pub_out) == 0)

  goto out;

    pad_leading_zeros(priv_out, BN_num_bytes(dh->priv_key), keylen);

    pad_leading_zeros(pub_out, BN_num_bytes(dh->pub_key), keylen);

#else

    DH_get0_key(dh, &pub_key, &priv_key);

    if(BN_bn2binpad(priv_key, priv_out, keylen) == -1)

  goto out;

    if(BN_bn2binpad(pub_key, pub_out, keylen) == -1)

  goto out;

#endif

    result = 1;

 out:

    DH_free(dh);

    return result;

}

int dh_compute_shared_key(uint8_t *shared_out, const uint8_t *priv, const uint8_t *pub, const uint8_t *prime, const size_t keylen)

{

    int result = 0;

    DH *dh;

    if(!(dh = DH_new()))

  goto out;

#if OPENSSL_VERSION_NUMBER < 0x10100000L || \

  (defined LIBRESSL_VERSION_NUMBER && LIBRESSL_VERSION_NUMBER < 0x30500000)

    dh->p = BN_bin2bn(prime, keylen, NULL);

    dh->priv_key = BN_bin2bn(priv, keylen, NULL);

#else

    if(!DH_set0_pqg(dh, BN_bin2bn(prime, keylen, NULL), NULL, BN_new()))

  goto out;

    if(!DH_set0_key(dh, NULL, BN_bin2bn(priv, keylen, NULL)))

  goto out;

#endif

    int shared_len = DH_compute_key(shared_out, BN_bin2bn(pub, keylen, NULL), dh);

    if(shared_len == -1)

        goto out;

    pad_leading_zeros(shared_out, shared_len, keylen);

    result = 1;

 out:

    DH_free(dh);

    return result;

}