+/*

+ zip_source_pkware.c -- Traditional PKWARE de/encryption routines

+ Copyright (C) 2009-2015 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);

+}