1 /* crypt.c -- base code for traditional PKWARE encryption
2 Version 1.2.0, September 16th, 2017
4 Copyright (C) 2012-2017 Nathan Moinvaziri
5 https://github.com/nmoinvaz/minizip
6 Copyright (C) 1998-2005 Gilles Vollant
7 Modifications for Info-ZIP crypting
8 http://www.winimage.com/zLibDll/minizip.html
9 Copyright (C) 2003 Terry Thorsen
11 This code is a modified version of crypting code in Info-ZIP distribution
13 Copyright (C) 1990-2000 Info-ZIP. All rights reserved.
15 This program is distributed under the terms of the same license as zlib.
16 See the accompanying LICENSE file for the full text of the license.
18 This encryption code is a direct transcription of the algorithm from
19 Roger Schlafly, described by Phil Katz in the file appnote.txt. This
20 file (appnote.txt) is distributed with the PKZIP program (even in the
21 version without encryption capabilities).
23 If you don't need crypting in your application, just define symbols
24 NOCRYPT and NOUNCRYPT.
34 # include <wincrypt.h>
36 # include <sys/stat.h>
45 /***************************************************************************/
47 #define CRC32(c, b) ((*(pcrc_32_tab+(((uint32_t)(c) ^ (b)) & 0xff))) ^ ((c) >> 8))
49 /***************************************************************************/
51 uint8_t decrypt_byte(uint32_t *pkeys)
53 unsigned temp; /* POTENTIAL BUG: temp*(temp^1) may overflow in an
54 * unpredictable manner on 16-bit systems; not a problem
55 * with any known compiler so far, though */
57 temp = ((uint32_t)(*(pkeys+2)) & 0xffff) | 2;
58 return (uint8_t)(((temp * (temp ^ 1)) >> 8) & 0xff);
61 uint8_t update_keys(uint32_t *pkeys, const z_crc_t *pcrc_32_tab, int32_t c)
63 (*(pkeys+0)) = (uint32_t)CRC32((*(pkeys+0)), c);
64 (*(pkeys+1)) += (*(pkeys+0)) & 0xff;
65 (*(pkeys+1)) = (*(pkeys+1)) * 134775813L + 1;
67 register int32_t keyshift = (int32_t)((*(pkeys + 1)) >> 24);
68 (*(pkeys+2)) = (uint32_t)CRC32((*(pkeys+2)), keyshift);
73 void init_keys(const char *passwd, uint32_t *pkeys, const z_crc_t *pcrc_32_tab)
75 *(pkeys+0) = 305419896L;
76 *(pkeys+1) = 591751049L;
77 *(pkeys+2) = 878082192L;
80 update_keys(pkeys, pcrc_32_tab, *passwd);
85 /***************************************************************************/
87 int cryptrand(unsigned char *buf, unsigned int len)
91 unsigned __int64 pentium_tsc[1];
96 if (CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT | CRYPT_SILENT))
98 result = CryptGenRandom(provider, len, buf);
99 CryptReleaseContext(provider, 0);
104 for (rlen = 0; rlen < (int)len; ++rlen)
107 QueryPerformanceCounter((LARGE_INTEGER *)pentium_tsc);
108 buf[rlen] = ((unsigned char*)pentium_tsc)[rlen % 8];
113 arc4random_buf(buf, len);
118 int crypthead(const char *passwd, uint8_t *buf, int buf_size, uint32_t *pkeys,
119 const z_crc_t *pcrc_32_tab, uint8_t verify1, uint8_t verify2)
121 uint8_t n = 0; /* index in random header */
122 uint8_t header[RAND_HEAD_LEN-2]; /* random header */
123 uint16_t t = 0; /* temporary */
125 if (buf_size < RAND_HEAD_LEN)
128 init_keys(passwd, pkeys, pcrc_32_tab);
130 /* First generate RAND_HEAD_LEN-2 random bytes. */
131 cryptrand(header, RAND_HEAD_LEN-2);
133 /* Encrypt random header (last two bytes is high word of crc) */
134 init_keys(passwd, pkeys, pcrc_32_tab);
136 for (n = 0; n < RAND_HEAD_LEN-2; n++)
137 buf[n] = (uint8_t)zencode(pkeys, pcrc_32_tab, header[n], t);
139 buf[n++] = (uint8_t)zencode(pkeys, pcrc_32_tab, verify1, t);
140 buf[n++] = (uint8_t)zencode(pkeys, pcrc_32_tab, verify2, t);
144 /***************************************************************************/