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 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 
  36 #include <stdlib.h>
  37 #include <string.h>
  38 
  39 #include "zipint.h"
  40 
  41 struct trad_pkware {
  42     int e[2];
  43 
  44     zip_uint32_t key[3];
  45 };
  46 
  47 #define HEADERLEN       12
  48 #define KEY0            305419896
  49 #define KEY1            591751049
  50 #define KEY2            878082192
  51 
  52 
  53 
  54 static void decrypt(struct trad_pkware *, zip_uint8_t *,
  55                     const zip_uint8_t *, zip_uint64_t, int);
  56 static int decrypt_header(struct zip_source *, struct trad_pkware *);
  57 static zip_int64_t pkware_decrypt(struct zip_source *, void *, void *,
  58                                   zip_uint64_t, enum zip_source_cmd);
  59 static void pkware_free(struct trad_pkware *);
  60 
  61 
  62 
  63 struct zip_source *
  64 zip_source_pkware(struct zip *za, struct zip_source *src,
  65                   zip_uint16_t em, int flags, const char *password)
  66 {
  67     struct trad_pkware *ctx;
  68     struct zip_source *s2;
  69 
  70     if (password == NULL || src == NULL || em != ZIP_EM_TRAD_PKWARE) {
  71         _zip_error_set(&za->error, ZIP_ER_INVAL, 0);
  72         return NULL;
  73     }
  74     if (flags & ZIP_CODEC_ENCODE) {
  75         _zip_error_set(&za->error, ZIP_ER_ENCRNOTSUPP, 0);
  76         return NULL;
  77     }
  78 
  79     if ((ctx=(struct trad_pkware *)malloc(sizeof(*ctx))) == NULL) {
  80         _zip_error_set(&za->error, ZIP_ER_MEMORY, 0);
  81         return NULL;
  82     }
  83 
  84     ctx->e[0] = ctx->e[1] = 0;
  85 
  86     ctx->key[0] = KEY0;
  87     ctx->key[1] = KEY1;
  88     ctx->key[2] = KEY2;
  89     decrypt(ctx, NULL, (const zip_uint8_t *)password, strlen(password), 1);
  90 
  91     if ((s2=zip_source_layered(za, src, pkware_decrypt, ctx)) == NULL) {
  92         pkware_free(ctx);
  93         return NULL;
  94     }
  95 
  96     return s2;
  97 }
  98 
  99 
 100 
 101 static void
 102 decrypt(struct trad_pkware *ctx, zip_uint8_t *out, const zip_uint8_t *in,
 103         zip_uint64_t len, int update_only)
 104 {
 105     zip_uint16_t tmp;
 106     zip_uint64_t i;
 107     Bytef b;
 108 
 109     for (i=0; i<len; i++) {
 110         b = in[i];
 111 
 112         if (!update_only) {
 113             /* decrypt next byte */
 114             tmp = (zip_uint16_t)(ctx->key[2] | 2);
 115             tmp = (tmp * (tmp ^ 1)) >> 8;
 116             b ^= tmp;
 117         }
 118 
 119         /* store cleartext */
 120         if (out)
 121             out[i] = b;
 122 
 123         /* update keys */
 124         ctx->key[0] = (zip_uint32_t)crc32(ctx->key[0] ^ 0xffffffffUL, &b, 1) ^ 0xffffffffUL;
 125         ctx->key[1] = (ctx->key[1] + (ctx->key[0] & 0xff)) * 134775813 + 1;
 126         b = ctx->key[1] >> 24;
 127         ctx->key[2] = (zip_uint32_t)crc32(ctx->key[2] ^ 0xffffffffUL, &b, 1) ^ 0xffffffffUL;
 128     }
 129 }
 130 
 131 
 132 
 133 static int
 134 decrypt_header(struct zip_source *src, struct trad_pkware *ctx)
 135 {
 136     zip_uint8_t header[HEADERLEN];
 137     struct zip_stat st;
 138     zip_int64_t n;
 139     unsigned short dostime, dosdate;
 140 
 141     if ((n=zip_source_read(src, header, HEADERLEN)) < 0) {
 142         zip_source_error(src, ctx->e, ctx->e+1);
 143         return -1;
 144     }
 145     
 146     if (n != HEADERLEN) {
 147         ctx->e[0] = ZIP_ER_EOF;
 148         ctx->e[1] = 0;
 149         return -1;
 150     }
 151 
 152     decrypt(ctx, header, header, HEADERLEN, 0);
 153 
 154     if (zip_source_stat(src, &st) < 0) {
 155         /* stat failed, skip password validation */
 156         return 0;
 157     }
 158 
 159     _zip_u2d_time(st.mtime, &dostime, &dosdate);
 160 
 161     if (header[HEADERLEN-1] != st.crc>>24
 162         && header[HEADERLEN-1] != dostime>>8) {
 163         ctx->e[0] = ZIP_ER_WRONGPASSWD;
 164         ctx->e[1] = 0;
 165         return -1;
 166     }
 167 
 168     return 0;
 169 }
 170 
 171 
 172 
 173 static zip_int64_t
 174 pkware_decrypt(struct zip_source *src, void *ud, void *data,
 175                zip_uint64_t len, enum zip_source_cmd cmd)
 176 {
 177     struct trad_pkware *ctx;
 178     zip_int64_t n;
 179 
 180     ctx = (struct trad_pkware *)ud;
 181 
 182     switch (cmd) {
 183     case ZIP_SOURCE_OPEN:
 184         if (decrypt_header(src, ctx) < 0)
 185             return -1;
 186         return 0;
 187 
 188     case ZIP_SOURCE_READ:
 189         if ((n=zip_source_read(src, data, len)) < 0)
 190             return ZIP_SOURCE_ERR_LOWER;
 191 
 192         decrypt((struct trad_pkware *)ud, (zip_uint8_t *)data, (zip_uint8_t *)data, (zip_uint64_t)n,
 193                 0);
 194         return n;
 195 
 196     case ZIP_SOURCE_CLOSE:
 197         return 0;
 198 
 199     case ZIP_SOURCE_STAT:
 200         {
 201             struct zip_stat *st;
 202 
 203             st = (struct zip_stat *)data;
 204 
 205             st->encryption_method = ZIP_EM_NONE;
 206             st->valid |= ZIP_STAT_ENCRYPTION_METHOD;
 207             /* TODO: deduce HEADERLEN from size for uncompressed */
 208             if (st->valid & ZIP_STAT_COMP_SIZE)
 209                 st->comp_size -= HEADERLEN;
 210         }
 211         return 0;
 212 
 213     case ZIP_SOURCE_ERROR:
 214         memcpy(data, ctx->e, sizeof(int)*2);
 215         return sizeof(int)*2;
 216 
 217     case ZIP_SOURCE_FREE:
 218         pkware_free(ctx);
 219         return 0;
 220 
 221     default:
 222         ctx->e[0] = ZIP_ER_INVAL;
 223         ctx->e[1] = 0;
 224         return -1;
 225     }
 226 }
 227 
 228 
 229 
 230 static void
 231 pkware_free(struct trad_pkware *ctx)
 232 {
 233     free(ctx);
 234 }