/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;

    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 = 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) {
            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: 2025-09-27 06:18

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		zip_source_t *
54	6.44k	zip_source_pkware_decode(zip_t za, zip_source_t src, zip_uint16_t em, int flags, const char *password) {
55	6.44k	struct trad_pkware *ctx;
56	6.44k	zip_source_t *s2;
57
58	6.44k	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	6.44k	if (flags & ZIP_CODEC_ENCODE) {
63	0	zip_error_set(&za->error, ZIP_ER_ENCRNOTSUPP, 0);
64	0	return NULL;
65	0	}
66
67	6.44k	if ((ctx = trad_pkware_new(password, &za->error)) == NULL) {
68	0	return NULL;
69	0	}
70
71	6.44k	if ((s2 = zip_source_layered(za, src, pkware_decrypt, ctx)) == NULL) {
72	0	trad_pkware_free(ctx);
73	0	return NULL;
74	0	}
75
76	6.44k	return s2;
77	6.44k	}
78
79
80		static int
81	5.11k	decrypt_header(zip_source_t src, struct trad_pkware ctx) {
82	5.11k	zip_uint8_t header[ZIP_CRYPTO_PKWARE_HEADERLEN];
83	5.11k	zip_stat_t st;
84	5.11k	zip_dostime_t dostime;
85	5.11k	zip_int64_t n;
86
87	5.11k	if ((n = zip_source_read(src, header, ZIP_CRYPTO_PKWARE_HEADERLEN)) < 0) {
88	856	zip_error_set_from_source(&ctx->error, src);
89	856	return -1;
90	856	}
91
92	4.25k	if (n != ZIP_CRYPTO_PKWARE_HEADERLEN) {
93	489	zip_error_set(&ctx->error, ZIP_ER_EOF, 0);
94	489	return -1;
95	489	}
96
97	3.77k	_zip_pkware_decrypt(&ctx->keys, header, header, ZIP_CRYPTO_PKWARE_HEADERLEN);
98
99	3.77k	if (zip_source_stat(src, &st) < 0 \|\| (st.valid & ZIP_STAT_CRC) == 0) {
100		/* skip password validation */
101	0	return 0;
102	0	}
103
104	3.77k	if (zip_source_get_dos_time(src, &dostime) <= 0) {
105	0	if ((st.valid & ZIP_STAT_MTIME) == 0) {
106		/* no date available, skip password validation */
107	0	return 0;
108	0	}
109
110	0	if (_zip_u2d_time(st.mtime, &dostime, &ctx->error) < 0) {
111	0	return -1;
112	0	}
113	0	}
114
115		/*
116		password verification - two ways:
117		- mtime - InfoZIP way, to avoid computing complete CRC before encrypting data
118		- CRC - old PKWare way
119		*/
120	3.77k	if (header[ZIP_CRYPTO_PKWARE_HEADERLEN - 1] == dostime.time >> 8
121	2.92k	\|\| header[ZIP_CRYPTO_PKWARE_HEADERLEN - 1] == st.crc >> 24) {
122	2.15k	return 0;
123	2.15k	}
124	1.61k	else {
125	1.61k	zip_error_set(&ctx->error, ZIP_ER_WRONGPASSWD, 0);
126	1.61k	return -1;
127	1.61k	}
128	3.77k	}
129
130
131		static zip_int64_t
132	31.5k	pkware_decrypt(zip_source_t src, void ud, void *data, zip_uint64_t len, zip_source_cmd_t cmd) {
133	31.5k	struct trad_pkware *ctx;
134	31.5k	zip_int64_t n;
135
136	31.5k	ctx = (struct trad_pkware *)ud;
137
138	31.5k	switch (cmd) {
139	5.11k	case ZIP_SOURCE_OPEN:
140	5.11k	_zip_pkware_keys_reset(&ctx->keys);
141	5.11k	_zip_pkware_decrypt(&ctx->keys, NULL, (const zip_uint8_t *)ctx->password, strlen(ctx->password));
142	5.11k	if (decrypt_header(src, ctx) < 0) {
143	2.95k	return -1;
144	2.95k	}
145	2.15k	return 0;
146
147	4.92k	case ZIP_SOURCE_READ:
148	4.92k	if ((n = zip_source_read(src, data, len)) < 0) {
149	834	zip_error_set_from_source(&ctx->error, src);
150	834	return -1;
151	834	}
152
153	4.08k	_zip_pkware_decrypt(&ctx->keys, (zip_uint8_t )data, (zip_uint8_t )data, (zip_uint64_t)n);
154	4.08k	return n;
155
156	2.15k	case ZIP_SOURCE_CLOSE:
157	2.15k	return 0;
158
159	2.64k	case ZIP_SOURCE_STAT: {
160	2.64k	zip_stat_t *st;
161
162	2.64k	st = (zip_stat_t *)data;
163
164	2.64k	st->encryption_method = ZIP_EM_NONE;
165	2.64k	st->valid \|= ZIP_STAT_ENCRYPTION_METHOD;
166	2.64k	if (st->valid & ZIP_STAT_COMP_SIZE) {
167	2.64k	st->comp_size -= ZIP_CRYPTO_PKWARE_HEADERLEN;
168	2.64k	}
169
170	2.64k	return 0;
171	4.92k	}
172
173	6.44k	case ZIP_SOURCE_SUPPORTS:
174	6.44k	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);
175
176	3.79k	case ZIP_SOURCE_ERROR:
177	3.79k	return zip_error_to_data(&ctx->error, data, len);
178
179	6.44k	case ZIP_SOURCE_FREE:
180	6.44k	trad_pkware_free(ctx);
181	6.44k	return 0;
182
183	0	default:
184	0	return zip_source_pass_to_lower_layer(src, data, len, cmd);
185	31.5k	}
186	31.5k	}
187
188
189		static struct trad_pkware *
190	6.44k	trad_pkware_new(const char password, zip_error_t error) {
191	6.44k	struct trad_pkware *ctx;
192
193	6.44k	if ((ctx = (struct trad_pkware )malloc(sizeof(ctx))) == NULL) {
194	0	zip_error_set(error, ZIP_ER_MEMORY, 0);
195	0	return NULL;
196	0	}
197
198	6.44k	if ((ctx->password = strdup(password)) == NULL) {
199	0	zip_error_set(error, ZIP_ER_MEMORY, 0);
200	0	free(ctx);
201	0	return NULL;
202	0	}
203
204	6.44k	zip_error_init(&ctx->error);
205
206	6.44k	return ctx;
207	6.44k	}
208
209
210		static void
211	6.44k	trad_pkware_free(struct trad_pkware *ctx) {
212	6.44k	if (ctx == NULL) {
213	0	return;
214	0	}
215
216	6.44k	free(ctx->password);
217	6.44k	free(ctx);
218	6.44k	}