root/ext/zip/lib/zip_source_pkware.c

DEFINITIONS

1. zip_source_pkware
2. decrypt
3. decrypt_header
4. pkware_decrypt
5. pkware_free

   1 /*
   2   zip_source_pkware.c -- Traditional PKWARE de/encryption routines
   3   Copyright (C) 2009-2015 Dieter Baron and Thomas Klausner
   4 
   5   This file is part of libzip, a library to manipulate ZIP archives.
   6   The authors can be contacted at <libzip@nih.at>
   7 
   8   Redistribution and use in source and binary forms, with or without
   9   modification, are permitted provided that the following conditions
  10   are met:
  11   1. Redistributions of source code must retain the above copyright
  12      notice, this list of conditions and the following disclaimer.
  13   2. Redistributions in binary form must reproduce the above copyright
  14      notice, this list of conditions and the following disclaimer in
  15      the documentation and/or other materials provided with the
  16      distribution.
  17   3. The names of the authors may not be used to endorse or promote
  18      products derived from this software without specific prior
  19      written permission.
  20  
  21   THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS
  22   OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  23   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24   ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
  25   DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
  27   GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
  29   IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  30   OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
  31   IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32 */
  33 
  34 
  35 #include <stdlib.h>
  36 #include <string.h>
  37 
  38 #include "zipint.h"
  39 
  40 struct trad_pkware {
  41     zip_error_t error;
  42     zip_uint32_t key[3];
  43 };
  44 
  45 #define HEADERLEN       12
  46 #define KEY0            305419896
  47 #define KEY1            591751049
  48 #define KEY2            878082192
  49 
  50 
  51 static void decrypt(struct trad_pkware *, zip_uint8_t *,
  52                     const zip_uint8_t *, zip_uint64_t, int);
  53 static int decrypt_header(zip_source_t *, struct trad_pkware *);
  54 static zip_int64_t pkware_decrypt(zip_source_t *, void *, void *,
  55                                   zip_uint64_t, zip_source_cmd_t);
  56 static void pkware_free(struct trad_pkware *);
  57 
  58 
  59 zip_source_t *
  60 zip_source_pkware(zip_t *za, zip_source_t *src,
  61                   zip_uint16_t em, int flags, const char *password)
  62 {
  63     struct trad_pkware *ctx;
  64     zip_source_t *s2;
  65 
  66     if (password == NULL || src == NULL || em != ZIP_EM_TRAD_PKWARE) {
  67         zip_error_set(&za->error, ZIP_ER_INVAL, 0);
  68         return NULL;
  69     }
  70     if (flags & ZIP_CODEC_ENCODE) {
  71         zip_error_set(&za->error, ZIP_ER_ENCRNOTSUPP, 0);
  72         return NULL;
  73     }
  74 
  75     if ((ctx=(struct trad_pkware *)malloc(sizeof(*ctx))) == NULL) {
  76         zip_error_set(&za->error, ZIP_ER_MEMORY, 0);
  77         return NULL;
  78     }
  79 
  80     zip_error_init(&ctx->error);
  81 
  82     ctx->key[0] = KEY0;
  83     ctx->key[1] = KEY1;
  84     ctx->key[2] = KEY2;
  85     decrypt(ctx, NULL, (const zip_uint8_t *)password, strlen(password), 1);
  86 
  87     if ((s2=zip_source_layered(za, src, pkware_decrypt, ctx)) == NULL) {
  88         pkware_free(ctx);
  89         return NULL;
  90     }
  91 
  92     return s2;
  93 }
  94 
  95 
  96 static void
  97 decrypt(struct trad_pkware *ctx, zip_uint8_t *out, const zip_uint8_t *in,
  98         zip_uint64_t len, int update_only)
  99 {
 100     zip_uint16_t tmp;
 101     zip_uint64_t i;
 102     Bytef b;
 103 
 104     for (i=0; i<len; i++) {
 105         b = in[i];
 106 
 107         if (!update_only) {
 108             /* decrypt next byte */
 109             tmp = (zip_uint16_t)(ctx->key[2] | 2);
 110             tmp = (zip_uint16_t)(((zip_uint32_t)tmp * (tmp ^ 1)) >> 8);
 111             b ^= (Bytef)tmp;
 112         }
 113 
 114         /* store cleartext */
 115         if (out)
 116             out[i] = b;
 117 
 118         /* update keys */
 119         ctx->key[0] = (zip_uint32_t)crc32(ctx->key[0] ^ 0xffffffffUL, &b, 1) ^ 0xffffffffUL;
 120         ctx->key[1] = (ctx->key[1] + (ctx->key[0] & 0xff)) * 134775813 + 1;
 121         b = (Bytef)(ctx->key[1] >> 24);
 122         ctx->key[2] = (zip_uint32_t)crc32(ctx->key[2] ^ 0xffffffffUL, &b, 1) ^ 0xffffffffUL;
 123     }
 124 }
 125 
 126 
 127 static int
 128 decrypt_header(zip_source_t *src, struct trad_pkware *ctx)
 129 {
 130     zip_uint8_t header[HEADERLEN];
 131     struct zip_stat st;
 132     zip_int64_t n;
 133     unsigned short dostime, dosdate;
 134 
 135     if ((n=zip_source_read(src, header, HEADERLEN)) < 0) {
 136         _zip_error_set_from_source(&ctx->error, src);
 137         return -1;
 138     }
 139     
 140     if (n != HEADERLEN) {
 141         zip_error_set(&ctx->error, ZIP_ER_EOF, 0);
 142         return -1;
 143     }
 144 
 145     decrypt(ctx, header, header, HEADERLEN, 0);
 146 
 147     if (zip_source_stat(src, &st) < 0) {
 148         /* stat failed, skip password validation */
 149         return 0;
 150     }
 151 
 152     _zip_u2d_time(st.mtime, &dostime, &dosdate);
 153 
 154     if (header[HEADERLEN-1] != st.crc>>24 && header[HEADERLEN-1] != dostime>>8) {
 155         zip_error_set(&ctx->error, ZIP_ER_WRONGPASSWD, 0);
 156         return -1;
 157     }
 158 
 159     return 0;
 160 }
 161 
 162 
 163 static zip_int64_t
 164 pkware_decrypt(zip_source_t *src, void *ud, void *data,
 165                zip_uint64_t len, zip_source_cmd_t cmd)
 166 {
 167     struct trad_pkware *ctx;
 168     zip_int64_t n;
 169 
 170     ctx = (struct trad_pkware *)ud;
 171 
 172     switch (cmd) {
 173         case ZIP_SOURCE_OPEN:
 174             if (decrypt_header(src, ctx) < 0)
 175                 return -1;
 176             return 0;
 177 
 178         case ZIP_SOURCE_READ:
 179             if ((n=zip_source_read(src, data, len)) < 0) {
 180                 _zip_error_set_from_source(&ctx->error, src);
 181                 return -1;
 182             }
 183 
 184             decrypt((struct trad_pkware *)ud, (zip_uint8_t *)data, (zip_uint8_t *)data, (zip_uint64_t)n, 0);
 185             return n;
 186 
 187         case ZIP_SOURCE_CLOSE:
 188             return 0;
 189 
 190         case ZIP_SOURCE_STAT:
 191         {
 192             zip_stat_t *st;
 193 
 194             st = (zip_stat_t *)data;
 195 
 196             st->encryption_method = ZIP_EM_NONE;
 197             st->valid |= ZIP_STAT_ENCRYPTION_METHOD;
 198             /* TODO: deduce HEADERLEN from size for uncompressed */
 199             if (st->valid & ZIP_STAT_COMP_SIZE)
 200                 st->comp_size -= HEADERLEN;
 201         
 202             return 0;
 203         }
 204             
 205         case ZIP_SOURCE_SUPPORTS:
 206             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);
 207 
 208         case ZIP_SOURCE_ERROR:
 209             return zip_error_to_data(&ctx->error, data, len);
 210 
 211         case ZIP_SOURCE_FREE:
 212             pkware_free(ctx);
 213             return 0;
 214 
 215         default:
 216             zip_error_set(&ctx->error, ZIP_ER_INVAL, 0);
 217             return -1;
 218     }
 219 }
 220 
 221 
 222 static void
 223 pkware_free(struct trad_pkware *ctx)
 224 {
 225     free(ctx);
 226 }