/*

  zip_pkware.c -- Traditional PKWARE de/encryption backend routines

  Copyright (C) 2009-2024 Dieter Baron and Thomas Klausner

  This file is part of libzip, a library to manipulate ZIP archives.

  The authors can be contacted at <info@libzip.org>

  Redistribution and use in source and binary forms, with or without

  modification, are permitted provided that the following conditions

  are met:

  1. Redistributions of source code must retain the above copyright

     notice, this list of conditions and the following disclaimer.

  2. Redistributions in binary form must reproduce the above copyright

     notice, this list of conditions and the following disclaimer in

     the documentation and/or other materials provided with the

     distribution.

  3. The names of the authors may not be used to endorse or promote

     products derived from this software without specific prior

     written permission.

  THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS

  OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

  ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY

  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE

  GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER

  IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR

  OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN

  IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

#include <stdlib.h>

#include <zlib.h>

#include "zipint.h"

#define PKWARE_KEY0 305419896

#define PKWARE_KEY1 591751049

#define PKWARE_KEY2 878082192

static void update_keys(zip_pkware_keys_t *keys, zip_uint8_t b) {

    keys->key[0] = (zip_uint32_t)crc32(keys->key[0] ^ 0xffffffffUL, &b, 1) ^ 0xffffffffUL;

    keys->key[1] = (keys->key[1] + (keys->key[0] & 0xff)) * 134775813 + 1;

    b = (zip_uint8_t)(keys->key[1] >> 24);

    keys->key[2] = (zip_uint32_t)crc32(keys->key[2] ^ 0xffffffffUL, &b, 1) ^ 0xffffffffUL;

}

static zip_uint8_t crypt_byte(zip_pkware_keys_t *keys) {

    zip_uint16_t tmp;

    tmp = (zip_uint16_t)(keys->key[2] | 2);

    tmp = (zip_uint16_t)(((zip_uint32_t)tmp * (tmp ^ 1)) >> 8);

    return (zip_uint8_t)tmp;

}

void _zip_pkware_keys_reset(zip_pkware_keys_t *keys) {

    keys->key[0] = PKWARE_KEY0;

    keys->key[1] = PKWARE_KEY1;

    keys->key[2] = PKWARE_KEY2;

}

void _zip_pkware_encrypt(zip_pkware_keys_t *keys, zip_uint8_t *out, const zip_uint8_t *in, zip_uint64_t len) {

    zip_uint64_t i;

    zip_uint8_t b;

    zip_uint8_t tmp;

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

        b = in[i];

        if (out != NULL) {

            tmp = crypt_byte(keys);

            update_keys(keys, b);

            b ^= tmp;

            out[i] = b;

        }

        else {

            /* during initialization, we're only interested in key updates */

            update_keys(keys, b);

        }

    }

}

void _zip_pkware_decrypt(zip_pkware_keys_t *keys, zip_uint8_t *out, const zip_uint8_t *in, zip_uint64_t len) {

    zip_uint64_t i;

    zip_uint8_t b;

    zip_uint8_t tmp;

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

        b = in[i];

        /* during initialization, we're only interested in key updates */

        if (out != NULL) {

            tmp = crypt_byte(keys);

            b ^= tmp;

            out[i] = b;

        }

        update_keys(keys, b);

    }

}