/*
?*?Copyright?2001?Niels?Provos?
?*?All?rights?reserved.
?*
?*?Redistribution?and?use?in?source?and?binary?forms?with?or?without
?*?modification?are?permitted?provided?that?the?following?conditions
?*?are?met:
?*?1.?Redistributions?of?source?code?must?retain?the?above?copyright
?*????notice?this?list?of?conditions?and?the?following?disclaimer.
?*?2.?Redistributions?in?binary?form?must?reproduce?the?above?copyright
?*????notice?this?list?of?conditions?and?the?following?disclaimer?in?the
?*????documentation?and/or?other?materials?provided?with?the?distribution.
?*?3.?All?advertising?materials?mentioning?features?or?use?of?this?software
?*????must?display?the?following?acknowledgement:
?*??????This?product?includes?software?developed?by?Niels?Provos.
?*?4.?The?name?of?the?author?may?not?be?used?to?endorse?or?promote?products
?*????derived?from?this?software?without?specific?prior?written?permission.
?*
?*?THIS?SOFTWARE?IS?PROVIDED?BY?THE?AUTHOR?‘‘AS?IS‘‘?AND?ANY?EXPRESS?OR
?*?IMPLIED?WARRANTIES?INCLUDING?BUT?NOT?LIMITED?TO?THE?IMPLIED?WARRANTIES
?*?OF?MERCHANTABILITY?AND?FITNESS?FOR?A?PARTICULAR?PURPOSE?ARE?DISCLAIMED.
?*?IN?NO?EVENT?SHALL?THE?AUTHOR?BE?LIABLE?FOR?ANY?DIRECT?INDIRECT
?*?INCIDENTAL?SPECIAL?EXEMPLARY?OR?CONSEQUENTIAL?DAMAGES?（INCLUDING?BUT
?*?NOT?LIMITED?TO?PROCUREMENT?OF?SUBSTITUTE?GOODS?OR?SERVICES;?LOSS?OF?USE
?*?DATA?OR?PROFITS;?OR?BUSINESS?INTERRUPTION）?HOWEVER?CAUSED?AND?ON?ANY
?*?THEORY?OF?LIABILITY?WHETHER?IN?CONTRACT?STRICT?LIABILITY?OR?TORT
?*?（INCLUDING?NEGLIGENCE?OR?OTHERWISE）?ARISING?IN?ANY?WAY?OUT?OF?THE?USE?OF
?*?THIS?SOFTWARE?EVEN?IF?ADVISED?OF?THE?POSSIBILITY?OF?SUCH?DAMAGE.
?*/

#include?

#include?“config.h“

#include?

#include?“arc4.h“

/*?
?*?An?arc4?stream?generator?is?used?for?encryption?and?pseudo-random
?*?numbers.
?*/

void
arc4_init（struct?arc4_stream?*as）
{
	int?????n;

	for?（n?=?0;?n?		as->s[n]?=?n;
	as->i?=?0;
	as->j?=?0;
}

u_int8_t
arc4_getbyte（struct?arc4_stream?*as）
{
	u_int8_t?si?sj;

	as->i?=?（as->i?+?1）;
	si?=?as->s[as->i];
	as->j?=?（as->j?+?si）;
	sj?=?as->s[as->j];
	as->s[as->i]?=?sj;
	as->s[as->j]?=?si;
	return?（as->s[（si?+?sj）?&?0xff]）;
}

void
arc4_skipbytes（struct?arc4_stream?*as?int?skip）
{
	u_int8_t?i?j?si?sj;
	u_int8_t?*s;

	s?=?as->s;
	i?=?as->i;
	j?=?as->j;

	while?（skip--?>?0）?{
		i?=?（i?+?1）?&?0xff;
		si?=?s[i];
		j?=?（si?+?j）?&?0xff;
		s[i]?=?sj?=?s[j];
		s[j]?=?si;
	}

	as->i?=?i;
	as->j?=?j;
}

u_int32_t
arc4_getword（struct?arc4_stream?*as）
{
	u_int32_t?val;
	val?=?arc4_getbyte（as）?<	val?|=?arc4_getbyte（as）?<	val?|=?arc4_getbyte（as）?<	val?|=?arc4_getbyte（as）;
	return?（val）;
}

void
arc4_addrandom（struct?arc4_stream?*as?u_char?*dat?int?datlen）
{
????????int?????n;
????????u_int8_t?si?ki?i?j?*s;

	s?=?as->s;
????????i?=?as->i?-?1;
	j?=?as->j;
	ki?=?0;
????????for?（n?=?0;?n?????????????????i++;
????????????????si?=?s[i];
????????????????j?=?（j?+?si?+?dat[ki]）;
????????