BSD 4 release

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

static char *sccsid = "@(#)crypt.c      4.1 (Berkeley) 10/1/80";
/*
*      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    *getpass();

setup(pw)
char *pw;
{
       int ic, i, k, temp, pf[2];
       unsigned random;
       char buf[13];
       long seed;

       strncpy(buf, pw, 8);
       while (*pw)
               *pw++ = '\0';
       buf[8] = buf[0];
       buf[9] = buf[1];
       pipe(pf);
       if (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);
       wait((int *)NULL);
       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;
       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;

       if (argc != 2){
               setup(getpass("Enter key:"));
       }
       else
               setup(argv[1]);
       n1 = 0;
       n2 = 0;

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