rc4_enc.c

Netscape公司提供的安全套接字层

/* WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
 *
 * Always modify rc4_enc.org since rc4_enc.c is automatically generated from
 * it during SSLeay configuration.
 * WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING 
 */

#include "rc4.h"

/* if this is defined data[i] is used instead of *data, this is a %20
 * speedup on x86 */
#undef RC4_INDEX

char *RC4_version="RC4 part of SSLeay 0.8.1 19-Jul-1997";

char *RC4_options()
	{
#ifdef RC4_INDEX
	if (sizeof(RC4_INT) == 1)
		return("rc4(idx,char)");
	else
		return("rc4(idx,int)");
#else
	if (sizeof(RC4_INT) == 1)
		return("rc4(ptr,char)");
	else
		return("rc4(ptr,int)");
#endif
	}

/* RC4 as implemented from a posting from
 * Newsgroups: sci.crypt
 * From: [e-mail] (David Sterndark)
 * Subject: RC4 Algorithm revealed.
 * Message-ID: <[e-mail]>
 * Date: Wed, 14 Sep 1994 06:35:31 GMT
 */

void RC4_set_key(key, len, data)
RC4_KEY *key;
int len;
register unsigned char *data;
	{
        register RC4_INT tmp;
        register int id1,id2;
        register RC4_INT *d;
        unsigned int i;
        
        d= &(key->data[0]);
	for (i=0; i<256; i++)
		d[i]=i;
        key->x = 0;     
        key->y = 0;     
        id1=id2=0;     

#define SK_LOOP(n) { \
		tmp=d[(n)]; \
		id2 = (data[id1] + tmp + id2) & 0xff; \
		if (++id1 == len) id1=0; \
		d[(n)]=d[id2]; \
		d[id2]=tmp; }

	for (i=0; i < 256; i+=4)
		{
		SK_LOOP(i+0);
		SK_LOOP(i+1);
		SK_LOOP(i+2);
		SK_LOOP(i+3);
		}
	}
    
void RC4(key, len, indata, outdata)
RC4_KEY *key;
unsigned long len;
unsigned char *indata;
unsigned char *outdata;
	{
        register RC4_INT *d;
        register RC4_INT x,y,tx,ty;
	int i;
        
        x=key->x;     
        y=key->y;     
        d=key->data; 

#define LOOP(in,out) \
		x=((x+1)&0xff); \
		tx=d[x]; \
		y=(tx+y)&0xff; \
		d[x]=ty=d[y]; \
		d[y]=tx; \
		(out) = d[(tx+ty)&0xff]^ (in);

#ifndef RC4_INDEX
#define RC4_LOOP(a,b,i)	LOOP(*((a)++),*((b)++))
#else
#define RC4_LOOP(a,b,i)	LOOP(a[i],b[i])
#endif

	i= -(int)len;
	i=(int)(len>>3L);
	if (i)
		{
		for (;;)
			{
			RC4_LOOP(indata,outdata,0);
			RC4_LOOP(indata,outdata,1);
			RC4_LOOP(indata,outdata,2);
			RC4_LOOP(indata,outdata,3);
			RC4_LOOP(indata,outdata,4);
			RC4_LOOP(indata,outdata,5);
			RC4_LOOP(indata,outdata,6);
			RC4_LOOP(indata,outdata,7);
#ifdef RC4_INDEX
			indata+=8;
			outdata+=8;
#endif
			if (--i == 0) break;
			}
		}
	i=(int)len&0x07;
	if (i)
		{
		for (;;)
			{
			RC4_LOOP(indata,outdata,0); if (--i == 0) break;
			RC4_LOOP(indata,outdata,1); if (--i == 0) break;
			RC4_LOOP(indata,outdata,2); if (--i == 0) break;
			RC4_LOOP(indata,outdata,3); if (--i == 0) break;
			RC4_LOOP(indata,outdata,4); if (--i == 0) break;
			RC4_LOOP(indata,outdata,5); if (--i == 0) break;
			RC4_LOOP(indata,outdata,6); if (--i == 0) break;
			}
		}               
	key->x=x;     
	key->y=y;
	}