1/* $NetBSD: crypt.h,v 1.1.1.1 2006/01/14 20:10:57 christos Exp $ */ 2 3/* crypt.h -- base code for crypt/uncrypt ZIPfile 4 5 6 Version 1.01e, February 12th, 2005 7 8 Copyright (C) 1998-2005 Gilles Vollant 9 10 This code is a modified version of crypting code in Infozip distribution 11 12 The encryption/decryption parts of this source code (as opposed to the 13 non-echoing password parts) were originally written in Europe. The 14 whole source package can be freely distributed, including from the USA. 15 (Prior to January 2000, re-export from the US was a violation of US law.) 16 17 This encryption code is a direct transcription of the algorithm from 18 Roger Schlafly, described by Phil Katz in the file appnote.txt. This 19 file (appnote.txt) is distributed with the PKZIP program (even in the 20 version without encryption capabilities). 21 22 If you don't need crypting in your application, just define symbols 23 NOCRYPT and NOUNCRYPT. 24 25 This code support the "Traditional PKWARE Encryption". 26 27 The new AES encryption added on Zip format by Winzip (see the page 28 http://www.winzip.com/aes_info.htm ) and PKWare PKZip 5.x Strong 29 Encryption is not supported. 30*/ 31 32#define CRC32(c, b) ((*(pcrc_32_tab+(((int)(c) ^ (b)) & 0xff))) ^ ((c) >> 8)) 33 34/*********************************************************************** 35 * Return the next byte in the pseudo-random sequence 36 */ 37static int decrypt_byte(unsigned long* pkeys, const unsigned long* pcrc_32_tab) 38{ 39 unsigned temp; /* POTENTIAL BUG: temp*(temp^1) may overflow in an 40 * unpredictable manner on 16-bit systems; not a problem 41 * with any known compiler so far, though */ 42 43 temp = ((unsigned)(*(pkeys+2)) & 0xffff) | 2; 44 return (int)(((temp * (temp ^ 1)) >> 8) & 0xff); 45} 46 47/*********************************************************************** 48 * Update the encryption keys with the next byte of plain text 49 */ 50static int update_keys(unsigned long* pkeys,const unsigned long* pcrc_32_tab,int c) 51{ 52 (*(pkeys+0)) = CRC32((*(pkeys+0)), c); 53 (*(pkeys+1)) += (*(pkeys+0)) & 0xff; 54 (*(pkeys+1)) = (*(pkeys+1)) * 134775813L + 1; 55 { 56 register int keyshift = (int)((*(pkeys+1)) >> 24); 57 (*(pkeys+2)) = CRC32((*(pkeys+2)), keyshift); 58 } 59 return c; 60} 61 62 63/*********************************************************************** 64 * Initialize the encryption keys and the random header according to 65 * the given password. 66 */ 67static void init_keys(const char* passwd,unsigned long* pkeys,const unsigned long* pcrc_32_tab) 68{ 69 *(pkeys+0) = 305419896L; 70 *(pkeys+1) = 591751049L; 71 *(pkeys+2) = 878082192L; 72 while (*passwd != '\0') { 73 update_keys(pkeys,pcrc_32_tab,(int)*passwd); 74 passwd++; 75 } 76} 77 78#define zdecode(pkeys,pcrc_32_tab,c) \ 79 (update_keys(pkeys,pcrc_32_tab,c ^= decrypt_byte(pkeys,pcrc_32_tab))) 80 81#define zencode(pkeys,pcrc_32_tab,c,t) \ 82 (t=decrypt_byte(pkeys,pcrc_32_tab), update_keys(pkeys,pcrc_32_tab,c), t^(c)) 83 84#ifdef INCLUDECRYPTINGCODE_IFCRYPTALLOWED 85 86#define RAND_HEAD_LEN 12 87 /* "last resort" source for second part of crypt seed pattern */ 88# ifndef ZCR_SEED2 89# define ZCR_SEED2 3141592654UL /* use PI as default pattern */ 90# endif 91 92static int crypthead(passwd, buf, bufSize, pkeys, pcrc_32_tab, crcForCrypting) 93 const char *passwd; /* password string */ 94 unsigned char *buf; /* where to write header */ 95 int bufSize; 96 unsigned long* pkeys; 97 const unsigned long* pcrc_32_tab; 98 unsigned long crcForCrypting; 99{ 100 int n; /* index in random header */ 101 int t; /* temporary */ 102 int c; /* random byte */ 103 unsigned char header[RAND_HEAD_LEN-2]; /* random header */ 104 static unsigned calls = 0; /* ensure different random header each time */ 105 106 if (bufSize<RAND_HEAD_LEN) 107 return 0; 108 109 /* First generate RAND_HEAD_LEN-2 random bytes. We encrypt the 110 * output of rand() to get less predictability, since rand() is 111 * often poorly implemented. 112 */ 113 if (++calls == 1) 114 { 115 srand((unsigned)(time(NULL) ^ ZCR_SEED2)); 116 } 117 init_keys(passwd, pkeys, pcrc_32_tab); 118 for (n = 0; n < RAND_HEAD_LEN-2; n++) 119 { 120 c = (rand() >> 7) & 0xff; 121 header[n] = (unsigned char)zencode(pkeys, pcrc_32_tab, c, t); 122 } 123 /* Encrypt random header (last two bytes is high word of crc) */ 124 init_keys(passwd, pkeys, pcrc_32_tab); 125 for (n = 0; n < RAND_HEAD_LEN-2; n++) 126 { 127 buf[n] = (unsigned char)zencode(pkeys, pcrc_32_tab, header[n], t); 128 } 129 buf[n++] = zencode(pkeys, pcrc_32_tab, (int)(crcForCrypting >> 16) & 0xff, t); 130 buf[n++] = zencode(pkeys, pcrc_32_tab, (int)(crcForCrypting >> 24) & 0xff, t); 131 return n; 132} 133 134#endif 135