Coverage Report

Created: 2025-07-23 08:18

/src/libzip/lib/zip_pkware.c
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/*
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  zip_pkware.c -- Traditional PKWARE de/encryption backend routines
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  Copyright (C) 2009-2022 Dieter Baron and Thomas Klausner
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  This file is part of libzip, a library to manipulate ZIP archives.
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  The authors can be contacted at <info@libzip.org>
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  Redistribution and use in source and binary forms, with or without
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  modification, are permitted provided that the following conditions
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  are met:
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  1. Redistributions of source code must retain the above copyright
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     notice, this list of conditions and the following disclaimer.
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  2. Redistributions in binary form must reproduce the above copyright
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     notice, this list of conditions and the following disclaimer in
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     the documentation and/or other materials provided with the
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     distribution.
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  3. The names of the authors may not be used to endorse or promote
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     products derived from this software without specific prior
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     written permission.
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  THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS
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  OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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  ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
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  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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  GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
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  IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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  OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
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  IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <stdlib.h>
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#include <zlib.h>
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#include "zipint.h"
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#define PKWARE_KEY0 305419896
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#define PKWARE_KEY1 591751049
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#define PKWARE_KEY2 878082192
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static void
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update_keys(zip_pkware_keys_t *keys, zip_uint8_t b) {
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    keys->key[0] = (zip_uint32_t)crc32(keys->key[0] ^ 0xffffffffUL, &b, 1) ^ 0xffffffffUL;
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    keys->key[1] = (keys->key[1] + (keys->key[0] & 0xff)) * 134775813 + 1;
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    b = (zip_uint8_t)(keys->key[1] >> 24);
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    keys->key[2] = (zip_uint32_t)crc32(keys->key[2] ^ 0xffffffffUL, &b, 1) ^ 0xffffffffUL;
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}
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static zip_uint8_t
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crypt_byte(zip_pkware_keys_t *keys) {
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    zip_uint16_t tmp;
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    tmp = (zip_uint16_t)(keys->key[2] | 2);
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    tmp = (zip_uint16_t)(((zip_uint32_t)tmp * (tmp ^ 1)) >> 8);
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    return (zip_uint8_t)tmp;
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}
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void
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_zip_pkware_keys_reset(zip_pkware_keys_t *keys) {
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    keys->key[0] = PKWARE_KEY0;
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    keys->key[1] = PKWARE_KEY1;
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    keys->key[2] = PKWARE_KEY2;
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}
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void
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_zip_pkware_encrypt(zip_pkware_keys_t *keys, zip_uint8_t *out, const zip_uint8_t *in, zip_uint64_t len) {
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    zip_uint64_t i;
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    zip_uint8_t b;
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    zip_uint8_t tmp;
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    for (i = 0; i < len; i++) {
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        b = in[i];
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        if (out != NULL) {
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            tmp = crypt_byte(keys);
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            update_keys(keys, b);
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            b ^= tmp;
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            out[i] = b;
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        }
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        else {
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            /* during initialization, we're only interested in key updates */
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            update_keys(keys, b);
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        }
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    }
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}
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void
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_zip_pkware_decrypt(zip_pkware_keys_t *keys, zip_uint8_t *out, const zip_uint8_t *in, zip_uint64_t len) {
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    zip_uint64_t i;
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    zip_uint8_t b;
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    zip_uint8_t tmp;
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    for (i = 0; i < len; i++) {
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        b = in[i];
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        /* during initialization, we're only interested in key updates */
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        if (out != NULL) {
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            tmp = crypt_byte(keys);
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            b ^= tmp;
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            out[i] = b;
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        }
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        update_keys(keys, b);
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    }
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}