arccode.c

来自「汇编源代码大全」· C语言 代码 · 共 44 行

/*
 * $Header: arccode.c,v 1.1 88/06/01 15:15:58 hyc Locked $
 */

/*
 * ARC - Archive utility - ARCCODE
 * 
 * Version 1.02, created on 01/20/86 at 13:33:35
 * 
 * (C) COPYRIGHT 1985 by System Enhancement Associates; ALL RIGHTS RESERVED
 * 
 * By:  Thom Henderson
 * 
 * Description: This file contains the routines used to encrypt and decrypt data
 * in an archive.  The encryption method is nothing fancy, being just a
 * routine XOR, but it is used on the packed data, and uses a variable length
 * key.  The end result is something that is in theory crackable, but I'd
 * hate to try it.  It should be more than sufficient for casual use.
 * 
 * Language: Computer Innovations Optimizing C86
 */
#include <stdio.h>
#include "arc.h"

static char    *p;		/* password pointer */

void
setcode()
{				/* get set for encoding/decoding */
	p = password;		/* reset password pointer */
}

unsigned char
code(c)				/* encode some character */
	char            c;	/* character to encode */
{
	if (p) {		/* if password is in use */
		if (!*p)	/* if we reached the end */
			p = password;	/* then wrap back to the start */
		return c ^ *p++;/* very simple here */
	} else
		return c;	/* else no encryption */
}