arcfour.c

[Luke Kenneth Casson Leighton]

you do realise that you have just broken ITAR restrictions regarding the
export of encryption software, and so have i?

luke

On Tue, 10 Feb 1998, Valdas Andrulis wrote:

> 
> 
> On Tue, 10 Feb 1998, Yaroslav L. Halchinsky wrote:
> 
> > Dear All!
> > Can anyone help me finding file `arcfour.c`?
> > Thank you!
> > 
> > Yaroslav Halchinsky
> > 
> 
> 
> <<<<
> <<<<<<arcfour.h>>>>>>
> <<<<
> 
> 
> /*
> 
> ARCFOUR cipher (based on a cipher posted on the Usenet in Spring-95).
> This cipher is widely believed and has been tested to be equivalent
> with the RC4 cipher from RSA Data Security, Inc.  (RC4 is a trademark
> of RSA Data Security)
> 
> */
> 
> /*
>  * $Id: arcfour.h,v 1.1.1.1 1996/02/18 21:38:11 ylo Exp $
>  * $Log: arcfour.h,v $
>  * Revision 1.1.1.1  1996/02/18 21:38:11  ylo
>  * 	Imported ssh-1.2.13.
>  *
>  * Revision 1.2  1995/07/13  01:30:25  ylo
>  * 	Added cvs log.
>  *
>  * $Endlog$
>  */
> 
> #ifndef ARCFOUR_H
> #define ARCFOUR_H
> 
> typedef struct
> {
>    unsigned int x;
>    unsigned int y;
>    unsigned char state[256];
> } ArcfourContext;
> 
> /* Initializes the context and sets the key. */
> void arcfour_init(ArcfourContext *ctx, const unsigned char *key, 
> 		  unsigned int keylen);
> 
> /* Returns the next pseudo-random byte from the arcfour (pseudo-random 
>    generator) stream. */
> unsigned int arcfour_byte(ArcfourContext *ctx);
> 
> /* Encrypts data. */
> void arcfour_encrypt(ArcfourContext *ctx, unsigned char *dest, 
> 		     const unsigned char *src, unsigned int len);
> 
> /* Decrypts data. */
> void arcfour_decrypt(ArcfourContext *ctx, unsigned char *dest, 
> 		     const unsigned char *src, unsigned int len);
> 
> #endif /* ARCFOUR_H */
> 
> <<<<
> <<<<<<arcfour.c>>>>>>
> <<<<
> 
> 
> /*
> 
> ARCFOUR cipher (based on a cipher posted on the Usenet in Spring-95).
> This cipher is widely believed and has been tested to be equivalent
> with the RC4 cipher from RSA Data Security, Inc.  (RC4 is a trademark
> of RSA Data Security)
> 
> */
> 
> /*
>  * $Id: arcfour.c,v 1.1.1.1 1996/02/18 21:38:11 ylo Exp $
>  * $Log: arcfour.c,v $
>  * Revision 1.1.1.1  1996/02/18 21:38:11  ylo
>  * 	Imported ssh-1.2.13.
>  *
>  * Revision 1.2  1995/07/13  01:29:59  ylo
>  * 	Added cvs log.
>  *
>  * $Endlog$
>  */
> 
> #include "assert.h"
> #include "arcfour.h"
> 
> /* arcfour added for SAMBA-NTDOMAIN */
> 
> void arcfour(unsigned char data[16], unsigned char data_out[16], unsigned char data_in[16])
> {
>     ArcfourContext ctx1;
>     
>     arcfour_init(&ctx1, data, 16);
>     arcfour_encrypt(&ctx1, data_out, data_in, 16);
> }
> 
> void arcfour_init(ArcfourContext *ctx, const unsigned char *key, 
> 		  unsigned int key_len)
> {
>   unsigned int t, u;
>   unsigned int keyindex;
>   unsigned int stateindex;
>   unsigned char* state;
>   unsigned int counter;
> 
>   assert(key_len > 0);
> 
>   state = &ctx->state[0];
>   ctx->x = 0;
>   ctx->y = 0;
>   for (counter = 0; counter < 256; counter++)
>     state[counter] = counter;
>   keyindex = 0;
>   stateindex = 0;
>   for (counter = 0; counter < 256; counter++)
>     {
>       t = state[counter];
>       stateindex = (stateindex + key[keyindex] + t) & 0xff;
>       u = state[stateindex];
>       state[stateindex] = t;
>       state[counter] = u;
>       if (++keyindex >= key_len)
> 	keyindex = 0;
>     }
> }
> 
> inline unsigned int arcfour_byte(ArcfourContext *ctx)
> {
>   unsigned int x;
>   unsigned int y;
>   unsigned int sx, sy;
>   unsigned char *state;
> 
>   state = ctx->state;
>   x = (ctx->x + 1) & 0xff;
>   sx = state[x];
>   y = (sx + ctx->y) & 0xff;
>   sy = state[y];
>   ctx->x = x;
>   ctx->y = y;
>   state[y] = sx;
>   state[x] = sy;
>   return state[(sx + sy) & 0xff];
> }
> 
> void arcfour_encrypt(ArcfourContext *ctx, unsigned char *dest, 
> 		     const unsigned char *src, unsigned int len)
> {
>   unsigned int i;
>   for (i = 0; i < len; i++)
>     dest[i] = src[i] ^ arcfour_byte(ctx);
> }
> 
> void arcfour_decrypt(ArcfourContext *ctx, unsigned char *dest, 
> 		 const unsigned char *src, unsigned int len)
> {
>   arcfour_encrypt(ctx, dest, src, len);
> }
> 
> 
> 
> 
> VAldas
> 
> 

<a href="mailto:lkcl at samba.anu.edu.au" > Luke Kenneth Casson Leighton  </a>
<a href="http://mailhost.cb1.com/~lkcl"> Samba and Network Development </a>
<a href="http://www.samba.co.uk"       > Samba and Network Consultancy </a>