/* zip_source_pkware.c -- Traditional PKWARE de/encryption routines Copyright (C) 2009-2016 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 <string.h> #include "zipint.h" struct trad_pkware { zip_error_t error; zip_uint32_t key[3]; }; #define HEADERLEN 12 #define KEY0 305419896 #define KEY1 591751049 #define KEY2 878082192 static void decrypt(struct trad_pkware *, zip_uint8_t *, const zip_uint8_t *, zip_uint64_t, int); static int decrypt_header(zip_source_t *, struct trad_pkware *); static zip_int64_t pkware_decrypt(zip_source_t *, void *, void *, zip_uint64_t, zip_source_cmd_t); static void pkware_free(struct trad_pkware *); zip_source_t * zip_source_pkware(zip_t *za, zip_source_t *src, zip_uint16_t em, int flags, const char *password) { struct trad_pkware *ctx; zip_source_t *s2; if (password == NULL || src == NULL || em != ZIP_EM_TRAD_PKWARE) { zip_error_set(&za->error, ZIP_ER_INVAL, 0); return NULL; } if (flags & ZIP_CODEC_ENCODE) { zip_error_set(&za->error, ZIP_ER_ENCRNOTSUPP, 0); return NULL; } if ((ctx=(struct trad_pkware *)malloc(sizeof(*ctx))) == NULL) { zip_error_set(&za->error, ZIP_ER_MEMORY, 0); return NULL; } zip_error_init(&ctx->error); ctx->key[0] = KEY0; ctx->key[1] = KEY1; ctx->key[2] = KEY2; decrypt(ctx, NULL, (const zip_uint8_t *)password, strlen(password), 1); if ((s2=zip_source_layered(za, src, pkware_decrypt, ctx)) == NULL) { pkware_free(ctx); return NULL; } return s2; } static void decrypt(struct trad_pkware *ctx, zip_uint8_t *out, const zip_uint8_t *in, zip_uint64_t len, int update_only) { zip_uint16_t tmp; zip_uint64_t i; Bytef b; for (i=0; i<len; i++) { b = in[i]; if (!update_only) { /* decrypt next byte */ tmp = (zip_uint16_t)(ctx->key[2] | 2); tmp = (zip_uint16_t)(((zip_uint32_t)tmp * (tmp ^ 1)) >> 8); b ^= (Bytef)tmp; } /* store cleartext */ if (out) out[i] = b; /* update keys */ ctx->key[0] = (zip_uint32_t)crc32(ctx->key[0] ^ 0xffffffffUL, &b, 1) ^ 0xffffffffUL; ctx->key[1] = (ctx->key[1] + (ctx->key[0] & 0xff)) * 134775813 + 1; b = (Bytef)(ctx->key[1] >> 24); ctx->key[2] = (zip_uint32_t)crc32(ctx->key[2] ^ 0xffffffffUL, &b, 1) ^ 0xffffffffUL; } } static int decrypt_header(zip_source_t *src, struct trad_pkware *ctx) { zip_uint8_t header[HEADERLEN]; struct zip_stat st; zip_int64_t n; unsigned short dostime, dosdate; if ((n=zip_source_read(src, header, HEADERLEN)) < 0) { _zip_error_set_from_source(&ctx->error, src); return -1; } if (n != HEADERLEN) { zip_error_set(&ctx->error, ZIP_ER_EOF, 0); return -1; } decrypt(ctx, header, header, HEADERLEN, 0); if (zip_source_stat(src, &st) < 0) { /* stat failed, skip password validation */ return 0; } _zip_u2d_time(st.mtime, &dostime, &dosdate); if (header[HEADERLEN-1] != st.crc>>24 && header[HEADERLEN-1] != dostime>>8) { zip_error_set(&ctx->error, ZIP_ER_WRONGPASSWD, 0); return -1; } return 0; } static zip_int64_t pkware_decrypt(zip_source_t *src, void *ud, void *data, zip_uint64_t len, zip_source_cmd_t cmd) { struct trad_pkware *ctx; zip_int64_t n; ctx = (struct trad_pkware *)ud; switch (cmd) { case ZIP_SOURCE_OPEN: if (decrypt_header(src, ctx) < 0) return -1; return 0; case ZIP_SOURCE_READ: if ((n=zip_source_read(src, data, len)) < 0) { _zip_error_set_from_source(&ctx->error, src); return -1; } decrypt((struct trad_pkware *)ud, (zip_uint8_t *)data, (zip_uint8_t *)data, (zip_uint64_t)n, 0); return n; case ZIP_SOURCE_CLOSE: return 0; case ZIP_SOURCE_STAT: { zip_stat_t *st; st = (zip_stat_t *)data; st->encryption_method = ZIP_EM_NONE; st->valid |= ZIP_STAT_ENCRYPTION_METHOD; /* TODO: deduce HEADERLEN from size for uncompressed */ if (st->valid & ZIP_STAT_COMP_SIZE) st->comp_size -= HEADERLEN; return 0; } case ZIP_SOURCE_SUPPORTS: return zip_source_make_command_bitmap(ZIP_SOURCE_OPEN, ZIP_SOURCE_READ, ZIP_SOURCE_CLOSE, ZIP_SOURCE_STAT, ZIP_SOURCE_ERROR, ZIP_SOURCE_FREE, -1); case ZIP_SOURCE_ERROR: return zip_error_to_data(&ctx->error, data, len); case ZIP_SOURCE_FREE: pkware_free(ctx); return 0; default: zip_error_set(&ctx->error, ZIP_ER_INVAL, 0); return -1; } } static void pkware_free(struct trad_pkware *ctx) { free(ctx); }