source: vendor/glibc/2.3.x/crypt/cert.c

/*
 * This crypt(3) validation program shipped with UFC-crypt
 * is derived from one distributed with Phil Karns PD DES package.
 *
 * @(#)cert.c   1.8 11 Aug 1996
 */

#include <stdio.h>
#include <stdlib.h>
#include "crypt.h"

int totfails = 0;

#if __STDC__ - 0
int main (int argc, char *argv[]);
void get8 (char *cp);
void put8 (char *cp);
void good_bye (void) __attribute__ ((noreturn));
#else
void get8(), put8();
#endif

void good_bye ()
{
  if(totfails == 0) {
    printf("Passed DES validation suite\n");
    exit(0);
  } else {
    printf("%d failures during DES validation suite!!!\n", totfails);
    exit(1);
  }
}

int
main(argc, argv)
     int argc;
     char *argv[];
{
        char key[64],plain[64],cipher[64],answer[64];
        int i;
        int test;
        int fail;

        for(test=0;!feof(stdin);test++){

                get8(key);
                printf(" K: "); put8(key);
                setkey(key);

                get8(plain);
                printf(" P: "); put8(plain);

                get8(answer);
                printf(" C: "); put8(answer);

                for(i=0;i<64;i++)
                        cipher[i] = plain[i];
                encrypt(cipher, 0);

                for(i=0;i<64;i++)
                        if(cipher[i] != answer[i])
                                break;
                fail = 0;
                if(i != 64){
                        printf(" Encrypt FAIL");
                        fail++; totfails++;
                }

                encrypt(cipher, 1);

                for(i=0;i<64;i++)
                        if(cipher[i] != plain[i])
                                break;
                if(i != 64){
                        printf(" Decrypt FAIL");
                        fail++; totfails++;
                }

                if(fail == 0)
                        printf(" OK");
                printf("\n");
        }
        good_bye();
}
void
get8(cp)
char *cp;
{
        int i,j,t;

        for(i=0;i<8;i++){
                scanf("%2x",&t);
                if(feof(stdin))
                  good_bye();
                for(j=0; j<8 ; j++) {
                  *cp++ = (t & (0x01 << (7-j))) != 0;
                }
        }
}
void
put8(cp)
char *cp;
{
        int i,j,t;

        for(i=0;i<8;i++){
          t = 0;
          for(j = 0; j<8; j++)
            t = (t<<1) | *cp++;
          printf("%02x", t);
        }
}