/src/libzip/lib/zip_source_pkware_decode.c

Source
/*
  zip_source_pkware_decode.c -- Traditional PKWARE decryption routines
  Copyright (C) 2009-2024 Dieter Baron and Thomas Klausner

  This file is part of libzip, a library to manipulate ZIP archives.
  The authors can be contacted at <info@libzip.org>

  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 {
    char *password;
    zip_pkware_keys_t keys;
    zip_error_t error;
};


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 struct trad_pkware *trad_pkware_new(const char *password, zip_error_t *error);
static void trad_pkware_free(struct trad_pkware *);


zip_source_t *zip_source_pkware_decode(zip_t *za, zip_source_t *src, zip_uint16_t em, int flags, const char *password) {
    struct trad_pkware *ctx;
    zip_source_t *s2;
    zip_stat_t st;

    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 (zip_source_stat(src, &st) != 0) {
        zip_error_set_from_source(&za->error, src);
        return NULL;
    }

    if ((st.valid & ZIP_STAT_COMP_SIZE) == 0 || st.comp_size < ZIP_CRYPTO_PKWARE_HEADERLEN) {
        zip_error_set(&za->error, ZIP_ER_OPNOTSUPP, 0);
        return NULL;
    }

    if ((ctx = trad_pkware_new(password, &za->error)) == NULL) {
        return NULL;
    }

    if ((s2 = zip_source_layered(za, src, pkware_decrypt, ctx)) == NULL) {
        trad_pkware_free(ctx);
        return NULL;
    }

    return s2;
}


static int decrypt_header(zip_source_t *src, struct trad_pkware *ctx) {
    zip_uint8_t header[ZIP_CRYPTO_PKWARE_HEADERLEN];
    zip_stat_t st;
    zip_dostime_t dostime;
    zip_int64_t n;

    if ((n = zip_source_read(src, header, ZIP_CRYPTO_PKWARE_HEADERLEN)) < 0) {
        zip_error_set_from_source(&ctx->error, src);
        return -1;
    }

    if (n != ZIP_CRYPTO_PKWARE_HEADERLEN) {
        zip_error_set(&ctx->error, ZIP_ER_EOF, 0);
        return -1;
    }

    _zip_pkware_decrypt(&ctx->keys, header, header, ZIP_CRYPTO_PKWARE_HEADERLEN);

    if (zip_source_stat(src, &st) < 0 || (st.valid & ZIP_STAT_CRC) == 0) {
        /* skip password validation */
        return 0;
    }

    if (zip_source_get_dos_time(src, &dostime) <= 0) {
        if ((st.valid & ZIP_STAT_MTIME) == 0) {
            /* no date available, skip password validation */
            return 0;
        }

        if (_zip_u2d_time(st.mtime, &dostime, &ctx->error) < 0) {
            return -1;
        }
    }

    /*
       password verification - two ways:
       - mtime - InfoZIP way, to avoid computing complete CRC before encrypting data
       - CRC - old PKWare way
    */
    if (header[ZIP_CRYPTO_PKWARE_HEADERLEN - 1] == dostime.time >> 8 || header[ZIP_CRYPTO_PKWARE_HEADERLEN - 1] == st.crc >> 24) {
        return 0;
    }
    else {
        zip_error_set(&ctx->error, ZIP_ER_WRONGPASSWD, 0);
        return -1;
    }
}


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:
        _zip_pkware_keys_reset(&ctx->keys);
        _zip_pkware_decrypt(&ctx->keys, NULL, (const zip_uint8_t *)ctx->password, strlen(ctx->password));
        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;
        }

        _zip_pkware_decrypt(&ctx->keys, (zip_uint8_t *)data, (zip_uint8_t *)data, (zip_uint64_t)n);
        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;
        if (st->valid & ZIP_STAT_COMP_SIZE) {
            if (st->comp_size < ZIP_CRYPTO_PKWARE_HEADERLEN) {
                zip_error_set(&ctx->error, ZIP_ER_DATA_LENGTH, 0);
                return -1;
            }
            st->comp_size -= ZIP_CRYPTO_PKWARE_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, ZIP_SOURCE_SUPPORTS_REOPEN, -1);

    case ZIP_SOURCE_ERROR:
        return zip_error_to_data(&ctx->error, data, len);

    case ZIP_SOURCE_FREE:
        trad_pkware_free(ctx);
        return 0;

    default:
        return zip_source_pass_to_lower_layer(src, data, len, cmd);
    }
}


static struct trad_pkware *trad_pkware_new(const char *password, zip_error_t *error) {
    struct trad_pkware *ctx;

    if ((ctx = (struct trad_pkware *)malloc(sizeof(*ctx))) == NULL) {
        zip_error_set(error, ZIP_ER_MEMORY, 0);
        return NULL;
    }

    if ((ctx->password = strdup(password)) == NULL) {
        zip_error_set(error, ZIP_ER_MEMORY, 0);
        free(ctx);
        return NULL;
    }

    zip_error_init(&ctx->error);

    return ctx;
}


static void trad_pkware_free(struct trad_pkware *ctx) {
    if (ctx == NULL) {
        return;
    }

    free(ctx->password);
    free(ctx);
}

Coverage Report

Created: 2026-06-02 06:56

Line	Count	Source
1		/*
2		zip_source_pkware_decode.c -- Traditional PKWARE decryption routines
3		Copyright (C) 2009-2024 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 <info@libzip.org>
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		char *password;
42		zip_pkware_keys_t keys;
43		zip_error_t error;
44		};
45
46
47		static int decrypt_header(zip_source_t , struct trad_pkware );
48		static zip_int64_t pkware_decrypt(zip_source_t , void , void *, zip_uint64_t, zip_source_cmd_t);
49		static struct trad_pkware trad_pkware_new(const char password, zip_error_t *error);
50		static void trad_pkware_free(struct trad_pkware *);
51
52
53	6.40k	zip_source_t zip_source_pkware_decode(zip_t za, zip_source_t src, zip_uint16_t em, int flags, const char password) {
54	6.40k	struct trad_pkware *ctx;
55	6.40k	zip_source_t *s2;
56	6.40k	zip_stat_t st;
57
58	6.40k	if (password == NULL \|\| src == NULL \|\| em != ZIP_EM_TRAD_PKWARE) {
59	0	zip_error_set(&za->error, ZIP_ER_INVAL, 0);
60	0	return NULL;
61	0	}
62	6.40k	if (flags & ZIP_CODEC_ENCODE) {
63	0	zip_error_set(&za->error, ZIP_ER_ENCRNOTSUPP, 0);
64	0	return NULL;
65	0	}
66
67	6.40k	if (zip_source_stat(src, &st) != 0) {
68	0	zip_error_set_from_source(&za->error, src);
69	0	return NULL;
70	0	}
71
72	6.40k	if ((st.valid & ZIP_STAT_COMP_SIZE) == 0 \|\| st.comp_size < ZIP_CRYPTO_PKWARE_HEADERLEN) {
73	576	zip_error_set(&za->error, ZIP_ER_OPNOTSUPP, 0);
74	576	return NULL;
75	576	}
76
77	5.82k	if ((ctx = trad_pkware_new(password, &za->error)) == NULL) {
78	0	return NULL;
79	0	}
80
81	5.82k	if ((s2 = zip_source_layered(za, src, pkware_decrypt, ctx)) == NULL) {
82	0	trad_pkware_free(ctx);
83	0	return NULL;
84	0	}
85
86	5.82k	return s2;
87	5.82k	}
88
89
90	4.51k	static int decrypt_header(zip_source_t src, struct trad_pkware ctx) {
91	4.51k	zip_uint8_t header[ZIP_CRYPTO_PKWARE_HEADERLEN];
92	4.51k	zip_stat_t st;
93	4.51k	zip_dostime_t dostime;
94	4.51k	zip_int64_t n;
95
96	4.51k	if ((n = zip_source_read(src, header, ZIP_CRYPTO_PKWARE_HEADERLEN)) < 0) {
97	695	zip_error_set_from_source(&ctx->error, src);
98	695	return -1;
99	695	}
100
101	3.81k	if (n != ZIP_CRYPTO_PKWARE_HEADERLEN) {
102	218	zip_error_set(&ctx->error, ZIP_ER_EOF, 0);
103	218	return -1;
104	218	}
105
106	3.59k	_zip_pkware_decrypt(&ctx->keys, header, header, ZIP_CRYPTO_PKWARE_HEADERLEN);
107
108	3.59k	if (zip_source_stat(src, &st) < 0 \|\| (st.valid & ZIP_STAT_CRC) == 0) {
109		/* skip password validation */
110	0	return 0;
111	0	}
112
113	3.59k	if (zip_source_get_dos_time(src, &dostime) <= 0) {
114	0	if ((st.valid & ZIP_STAT_MTIME) == 0) {
115		/* no date available, skip password validation */
116	0	return 0;
117	0	}
118
119	0	if (_zip_u2d_time(st.mtime, &dostime, &ctx->error) < 0) {
120	0	return -1;
121	0	}
122	0	}
123
124		/*
125		password verification - two ways:
126		- mtime - InfoZIP way, to avoid computing complete CRC before encrypting data
127		- CRC - old PKWare way
128		*/
129	3.59k	if (header[ZIP_CRYPTO_PKWARE_HEADERLEN - 1] == dostime.time >> 8 \|\| header[ZIP_CRYPTO_PKWARE_HEADERLEN - 1] == st.crc >> 24) {
130	2.45k	return 0;
131	2.45k	}
132	1.14k	else {
133	1.14k	zip_error_set(&ctx->error, ZIP_ER_WRONGPASSWD, 0);
134	1.14k	return -1;
135	1.14k	}
136	3.59k	}
137
138
139	29.5k	static zip_int64_t pkware_decrypt(zip_source_t src, void ud, void *data, zip_uint64_t len, zip_source_cmd_t cmd) {
140	29.5k	struct trad_pkware *ctx;
141	29.5k	zip_int64_t n;
142
143	29.5k	ctx = (struct trad_pkware *)ud;
144
145	29.5k	switch (cmd) {
146	4.51k	case ZIP_SOURCE_OPEN:
147	4.51k	_zip_pkware_keys_reset(&ctx->keys);
148	4.51k	_zip_pkware_decrypt(&ctx->keys, NULL, (const zip_uint8_t *)ctx->password, strlen(ctx->password));
149	4.51k	if (decrypt_header(src, ctx) < 0) {
150	2.05k	return -1;
151	2.05k	}
152	2.45k	return 0;
153
154	4.91k	case ZIP_SOURCE_READ:
155	4.91k	if ((n = zip_source_read(src, data, len)) < 0) {
156	930	zip_error_set_from_source(&ctx->error, src);
157	930	return -1;
158	930	}
159
160	3.98k	_zip_pkware_decrypt(&ctx->keys, (zip_uint8_t )data, (zip_uint8_t )data, (zip_uint64_t)n);
161	3.98k	return n;
162
163	2.45k	case ZIP_SOURCE_CLOSE:
164	2.45k	return 0;
165
166	3.01k	case ZIP_SOURCE_STAT: {
167	3.01k	zip_stat_t *st;
168
169	3.01k	st = (zip_stat_t *)data;
170
171	3.01k	st->encryption_method = ZIP_EM_NONE;
172	3.01k	st->valid \|= ZIP_STAT_ENCRYPTION_METHOD;
173	3.01k	if (st->valid & ZIP_STAT_COMP_SIZE) {
174	3.01k	if (st->comp_size < ZIP_CRYPTO_PKWARE_HEADERLEN) {
175	0	zip_error_set(&ctx->error, ZIP_ER_DATA_LENGTH, 0);
176	0	return -1;
177	0	}
178	3.01k	st->comp_size -= ZIP_CRYPTO_PKWARE_HEADERLEN;
179	3.01k	}
180
181	3.01k	return 0;
182	3.01k	}
183
184	5.82k	case ZIP_SOURCE_SUPPORTS:
185	5.82k	return zip_source_make_command_bitmap(ZIP_SOURCE_OPEN, ZIP_SOURCE_READ, ZIP_SOURCE_CLOSE, ZIP_SOURCE_STAT, ZIP_SOURCE_ERROR, ZIP_SOURCE_FREE, ZIP_SOURCE_SUPPORTS_REOPEN, -1);
186
187	2.98k	case ZIP_SOURCE_ERROR:
188	2.98k	return zip_error_to_data(&ctx->error, data, len);
189
190	5.82k	case ZIP_SOURCE_FREE:
191	5.82k	trad_pkware_free(ctx);
192	5.82k	return 0;
193
194	0	default:
195	0	return zip_source_pass_to_lower_layer(src, data, len, cmd);
196	29.5k	}
197	29.5k	}
198
199
200	5.82k	static struct trad_pkware trad_pkware_new(const char password, zip_error_t *error) {
201	5.82k	struct trad_pkware *ctx;
202
203	5.82k	if ((ctx = (struct trad_pkware )malloc(sizeof(ctx))) == NULL) {
204	0	zip_error_set(error, ZIP_ER_MEMORY, 0);
205	0	return NULL;
206	0	}
207
208	5.82k	if ((ctx->password = strdup(password)) == NULL) {
209	0	zip_error_set(error, ZIP_ER_MEMORY, 0);
210	0	free(ctx);
211	0	return NULL;
212	0	}
213
214	5.82k	zip_error_init(&ctx->error);
215
216	5.82k	return ctx;
217	5.82k	}
218
219
220	5.82k	static void trad_pkware_free(struct trad_pkware *ctx) {
221	5.82k	if (ctx == NULL) {
222	0	return;
223	0	}
224
225	5.82k	free(ctx->password);
226	5.82k	free(ctx);
227	5.82k	}