/* zip_pkware.c -- Traditional PKWARE de/encryption backend routines Copyright (C) 2009-2020 Dieter Baron and Thomas Klausner This file is part of libzip, a library to manipulate ZIP archives. The authors can be contacted at <libzip@nih.at> 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); } }