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 *
zip_source_pkware(zip_t * za,zip_source_t * src,zip_uint16_t em,int flags,const char * password)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
decrypt(struct trad_pkware * ctx,zip_uint8_t * out,const zip_uint8_t * in,zip_uint64_t len,int update_only)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
decrypt_header(zip_source_t * src,struct trad_pkware * ctx)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
pkware_decrypt(zip_source_t * src,void * ud,void * data,zip_uint64_t len,zip_source_cmd_t cmd)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
pkware_free(struct trad_pkware * ctx)223 pkware_free(struct trad_pkware *ctx)
224 {
225 free(ctx);
226 }
227
