1 /* 2 * ---------------------------------------------------------------------------- 3 * "THE BEER-WARE LICENSE" (Revision 42): 4 * <phk@login.dknet.dk> wrote this file. As long as you retain this notice you 5 * can do whatever you want with this stuff. If we meet some day, and you think 6 * this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp 7 * ---------------------------------------------------------------------------- 8 * 9 * $Id: crypt.c,v 1.3 1995/05/30 05:42:22 rgrimes Exp $ 10 * 11 */ 12 13 #if defined(LIBC_SCCS) && !defined(lint) 14 static char rcsid[] = "$Header: /home/ncvs/src/lib/libcrypt/crypt.c,v 1.3 1995/05/30 05:42:22 rgrimes Exp $"; 15 #endif /* LIBC_SCCS and not lint */ 16 17 #include <unistd.h> 18 #include <stdio.h> 19 #include <string.h> 20 #include <md5.h> 21 22 static unsigned char itoa64[] = /* 0 ... 63 => ascii - 64 */ 23 "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; 24 25 static void 26 to64(s, v, n) 27 char *s; 28 unsigned long v; 29 int n; 30 { 31 while (--n >= 0) { 32 *s++ = itoa64[v&0x3f]; 33 v >>= 6; 34 } 35 } 36 37 /* 38 * UNIX password 39 * 40 * Use MD5 for what it is best at... 41 */ 42 43 char * 44 crypt(pw, salt) 45 register const char *pw; 46 register const char *salt; 47 { 48 static char *magic = "$1$"; /* 49 * This string is magic for 50 * this algorithm. Having 51 * it this way, we can get 52 * get better later on 53 */ 54 static char passwd[120], *p; 55 static const char *sp,*ep; 56 unsigned char final[16]; 57 int sl,pl,i,j; 58 MD5_CTX ctx,ctx1; 59 unsigned long l; 60 61 /* Refine the Salt first */ 62 sp = salt; 63 64 /* If it starts with the magic string, then skip that */ 65 if(!strncmp(sp,magic,strlen(magic))) 66 sp += strlen(magic); 67 68 /* It stops at the first '$', max 8 chars */ 69 for(ep=sp;*ep && *ep != '$' && ep < (sp+8);ep++) 70 continue; 71 72 /* get the length of the true salt */ 73 sl = ep - sp; 74 75 MD5Init(&ctx); 76 77 /* The password first, since that is what is most unknown */ 78 MD5Update(&ctx,pw,strlen(pw)); 79 80 /* Then our magic string */ 81 MD5Update(&ctx,magic,strlen(magic)); 82 83 /* Then the raw salt */ 84 MD5Update(&ctx,sp,sl); 85 86 /* Then just as many characters of the MD5(pw,salt,pw) */ 87 MD5Init(&ctx1); 88 MD5Update(&ctx1,pw,strlen(pw)); 89 MD5Update(&ctx1,sp,sl); 90 MD5Update(&ctx1,pw,strlen(pw)); 91 MD5Final(final,&ctx1); 92 for(pl = strlen(pw); pl > 0; pl -= 16) 93 MD5Update(&ctx,final,pl>16 ? 16 : pl); 94 95 /* Don't leave anything around in vm they could use. */ 96 memset(final,0,sizeof final); 97 98 /* Then something really weird... */ 99 for (j=0,i = strlen(pw); i ; i >>= 1) 100 if(i&1) 101 MD5Update(&ctx, final+j, 1); 102 else 103 MD5Update(&ctx, pw+j, 1); 104 105 /* Now make the output string */ 106 strcpy(passwd,magic); 107 strncat(passwd,sp,sl); 108 strcat(passwd,"$"); 109 110 MD5Final(final,&ctx); 111 112 /* 113 * and now, just to make sure things don't run too fast 114 * On a 60 Mhz Pentium this takes 34 msec, so you would 115 * need 30 seconds to build a 1000 entry dictionary... 116 */ 117 for(i=0;i<1000;i++) { 118 MD5Init(&ctx1); 119 if(i & 1) 120 MD5Update(&ctx1,pw,strlen(pw)); 121 else 122 MD5Update(&ctx1,final,16); 123 124 if(i % 3) 125 MD5Update(&ctx1,sp,sl); 126 127 if(i % 7) 128 MD5Update(&ctx1,pw,strlen(pw)); 129 130 if(i & 1) 131 MD5Update(&ctx1,final,16); 132 else 133 MD5Update(&ctx1,pw,strlen(pw)); 134 MD5Final(final,&ctx1); 135 } 136 137 p = passwd + strlen(passwd); 138 139 l = (final[ 0]<<16) | (final[ 6]<<8) | final[12]; to64(p,l,4); p += 4; 140 l = (final[ 1]<<16) | (final[ 7]<<8) | final[13]; to64(p,l,4); p += 4; 141 l = (final[ 2]<<16) | (final[ 8]<<8) | final[14]; to64(p,l,4); p += 4; 142 l = (final[ 3]<<16) | (final[ 9]<<8) | final[15]; to64(p,l,4); p += 4; 143 l = (final[ 4]<<16) | (final[10]<<8) | final[ 5]; to64(p,l,4); p += 4; 144 l = final[11] ; to64(p,l,2); p += 2; 145 *p = '\0'; 146 147 /* Don't leave anything around in vm they could use. */ 148 memset(final,0,sizeof final); 149 150 return passwd; 151 } 152 153