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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <termios.h>
#include <signal.h>
#include "skey.h"
#include "mdx.h"
/* Crunch a key:
* concatenate the seed and the password, run through MDX and
* collapse to 64 bits. This is defined as the user's starting key.
*/
int
keycrunch(result,seed,passwd)
char *result; /* 8-byte result */
char *seed; /* Seed, any length */
char *passwd; /* Password, any length */
{
char *buf;
MDX_CTX md;
u_long results[4];
unsigned int buflen;
buflen = strlen(seed) + strlen(passwd);
if((buf = malloc(buflen+1)) == NULL)
return -1;
strcpy(buf,seed);
strcat(buf,passwd);
/* Crunch the key through MD[45] */
sevenbit(buf);
MDXInit(&md);
MDXUpdate(&md,(unsigned char *)buf,buflen);
MDXFinal((unsigned char *)results,&md);
free(buf);
results[0] ^= results[2];
results[1] ^= results[3];
memcpy(result,(char *)results,8);
return 0;
}
/* The one-way function f(). Takes 8 bytes and returns 8 bytes in place */
void
f(x)
char *x;
{
MDX_CTX md;
u_long results[4];
MDXInit(&md);
MDXUpdate(&md,(unsigned char *)x,8);
MDXFinal((unsigned char *)results,&md);
/* Fold 128 to 64 bits */
results[0] ^= results[2];
results[1] ^= results[3];
memcpy(x,(char *)results,8);
}
/* Strip trailing cr/lf from a line of text */
void
rip(buf)
char *buf;
{
buf[strcspn(buf, "\r\n")] = 0;
}
static struct termios saved_ttymode;
static void interrupt(sig)
int sig;
{
tcsetattr(0, TCSANOW, &saved_ttymode);
exit(1);
}
char *
readpass(buf,n)
char *buf;
int n;
{
struct termios noecho_ttymode;
void (*oldsig)();
/* Save normal line editing modes */
tcgetattr(0, &saved_ttymode);
if ((oldsig = signal(SIGINT, SIG_IGN)) != SIG_IGN)
signal(SIGINT, interrupt);
/* Turn off echoing */
tcgetattr(0, &noecho_ttymode);
noecho_ttymode.c_lflag &= ~ECHO;
tcsetattr(0, TCSANOW, &noecho_ttymode);
fgets(buf,n,stdin);
rip(buf);
/* Restore previous tty modes */
tcsetattr(0, TCSANOW, &saved_ttymode);
if (oldsig != SIG_IGN)
signal(SIGINT, oldsig);
/*
after the secret key is taken from the keyboard, the line feed is
written to standard error instead of standard output. That means that
anyone using the program from a terminal won't notice, but capturing
standard output will get the key words without a newline in front of
them.
*/
fprintf(stderr, "\n");
fflush(stderr);
sevenbit(buf);
return buf;
}
sevenbit(s)
char *s;
{
/* make sure there are only 7 bit code in the line*/
while(*s){
*s &= 0x7f;
s++;
}
}
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