BSD 4_3 release

[unix-history] / usr / src / usr.bin / crypt.c

static char *sccsid = "@(#)crypt.c      4.3 (Berkeley) 1/25/85";

/*
*      A one-rotor machine designed along the lines of Enigma
*      but considerably trivialized.
*/

#define ECHO 010
#include <stdio.h>
#define ROTORSZ 256
#define MASK 0377
char    t1[ROTORSZ];
char    t2[ROTORSZ];
char    t3[ROTORSZ];
char    deck[ROTORSZ];
char    *getpass();
char    buf[13];

setup(pw)
char *pw;
{
       int ic, i, k, temp, pf[2];
       int pid, wpid;
       unsigned random;
       long seed;

       strncpy(buf, pw, 8);
       while (*pw)
               *pw++ = '\0';
       buf[8] = buf[0];
       buf[9] = buf[1];
       pipe(pf);
       if ((pid=fork())==0) {
               close(0);
               close(1);
               dup(pf[0]);
               dup(pf[1]);
               execl("/usr/lib/makekey", "-", 0);
               execl("/lib/makekey", "-", 0);
               exit(1);
       }
       write(pf[1], buf, 10);
       while ((wpid = wait((int *)NULL)) != -1 && wpid != pid)
           ;
       if (read(pf[0], buf, 13) != 13) {
               fprintf(stderr, "crypt: cannot generate key\n");
               exit(1);
       }
       seed = 123;
       for (i=0; i<13; i++)
               seed = seed*buf[i] + i;
       for(i=0;i<ROTORSZ;i++) {
               t1[i] = i;
               deck[i] = i;
       }
       for(i=0;i<ROTORSZ;i++) {
               seed = 5*seed + buf[i%13];
               random = seed % 65521;
               k = ROTORSZ-1 - i;
               ic = (random&MASK)%(k+1);
               random >>= 8;
               temp = t1[k];
               t1[k] = t1[ic];
               t1[ic] = temp;
               if(t3[k]!=0) continue;
               ic = (random&MASK) % k;
               while(t3[ic]!=0) ic = (ic+1) % k;
               t3[k] = ic;
               t3[ic] = k;
       }
       for(i=0;i<ROTORSZ;i++)
               t2[t1[i]&MASK] = i;
}

main(argc, argv)
char *argv[];
{
       register i, n1, n2, nr1, nr2;
       int secureflg = 0;

       if (argc > 1 && argv[1][0] == '-' && argv[1][1] == 's') {
               argc--;
               argv++;
               secureflg = 1;
       }
       if (argc != 2){
               setup(getpass("Enter key:"));
       }
       else
               setup(argv[1]);
       n1 = 0;
       n2 = 0;
       nr2 = 0;

       while((i=getchar()) >=0) {
               if (secureflg) {
                       nr1 = deck[n1]&MASK;
                       nr2 = deck[nr1]&MASK;
               } else {
                       nr1 = n1;
               }
               i = t2[(t3[(t1[(i+nr1)&MASK]+nr2)&MASK]-nr2)&MASK]-nr1;
               putchar(i);
               n1++;
               if(n1==ROTORSZ) {
                       n1 = 0;
                       n2++;
                       if(n2==ROTORSZ) n2 = 0;
                       if (secureflg) {
                               shuffle(deck);
                       } else {
                               nr2 = n2;
                       }
               }
       }
}

shuffle(deck)
       char deck[];
{
       int i, ic, k, temp;
       unsigned random;
       static long seed = 123;

       for(i=0;i<ROTORSZ;i++) {
               seed = 5*seed + buf[i%13];
               random = seed % 65521;
               k = ROTORSZ-1 - i;
               ic = (random&MASK)%(k+1);
               temp = deck[k];
               deck[k] = deck[ic];
               deck[ic] = temp;
       }
}