/*
 ******************************************************************************
 *                     INTERPEAK SOURCE FILE
 *
 *   Document no: @(#) $Name: VXWORKS_ITER40_2019102207 $ $RCSfile: ip8021x_rc4.c,v $ $Revision: 1.3 $
 *   $Source: /home/interpeak/CVSRoot/ip8021x/src/ip8021x_rc4.c,v $
 *   $Author: myakan $
 *   $State: Exp $ $Locker:  $
 *
 *   Copyright 2000-2006 Interpeak AB (http://www.interpeak.se). All rights reserved.
 *   Design and implementation by Roger Boden <roger@interpeak.se>
 ******************************************************************************
 */


/*
 ****************************************************************************
 * 1                    DESCRIPTION
 ****************************************************************************
 */

/*
 ****************************************************************************
 * 2                    CONFIGURATION
 ****************************************************************************
 */

#include "ip8021x_config.h"


/*
 ****************************************************************************
 * 3                    INCLUDE FILES
 ****************************************************************************
 */

#include <ipcom_type.h>
#include <ipcom_cstyle.h>

#include "ip8021x.h"
#include "ip8021x_h.h"


/*
 ****************************************************************************
 * 4                    DEFINES
 ****************************************************************************
 */
#define IP8021X_RC4_SWAP(a,b) do { Ip_u8 t = S[a]; S[a] = S[b]; S[b] = t; } while(0)

/*
 ****************************************************************************
 * 5                    TYPES
 ****************************************************************************
 */

/*
 ****************************************************************************
 * 6                    EXTERN PROTOTYPES
 ****************************************************************************
 */

/*
 ****************************************************************************
 * 7                    LOCAL PROTOTYPES
 ****************************************************************************
 */

/*
 ****************************************************************************
 * 8                    DATA
 ****************************************************************************
 */

/*
 ****************************************************************************
 * 9                    STATIC FUNCTIONS
 ****************************************************************************
 */

/*
 ****************************************************************************
 * 10                   GLOBAL FUNCTIONS
 ****************************************************************************
 */


/*
 *===========================================================================
 *                    ip8021x_rc4_skip
 *===========================================================================
 * Description:
 * Parameters:
 * Returns:
 *
 */
IP_GLOBAL void
ip8021x_rc4_skip(Ip_u8 *key, Ip_size_t keylen, Ip_size_t skip, Ip_u8 *data, Ip_size_t data_len)
{
	Ip_u32 i;
    Ip_u32 j;
    Ip_u32 k;
	Ip_u8 S[256];
	unsigned int pos;

	/* Initialize RC4 S-box */
	for (i = 0; i < 256; i++)
		S[i] = i; /*lint !e734*/
	j = 0;
	pos = 0;
	for (i = 0; i < 256; i++) {
		j = (j + S[i] + key[pos]) & 0xff;
		pos++;
		if (pos >= keylen)
			pos = 0;
		IP8021X_RC4_SWAP(i, j);
	}

	/* Skip the first 'skip' bytes of the key stream */
	i = 0;
    j = 0;
	for (k = 0; k < skip; k++) {
		i = (i + 1) & 0xff;
		j = (j + S[i]) & 0xff;
		IP8021X_RC4_SWAP(i, j);
	}

	/* Encrypt/decrypt the data */
	for (k = 0; k < data_len; k++) {
		i = (i + 1) & 0xff;
		j = (j + S[i]) & 0xff;
		IP8021X_RC4_SWAP(i, j);
		*data++ ^= S[(S[i] + S[j]) & 0xff];
	}
}


/*
 *===========================================================================
 *                    ip8021x_rc4
 *===========================================================================
 * Description:
 * Parameters:
 * Returns:
 *
 */
IP_GLOBAL void
ip8021x_rc4(Ip_u8 *key, Ip_size_t key_len, Ip_u8 *buf, Ip_size_t len)
{
	ip8021x_rc4_skip(key, key_len, 0, buf, len);
}


/*
 ****************************************************************************
 * 11                   PUBLIC FUNCTIONS
 ****************************************************************************
 */

/*
 ****************************************************************************
 *                      END OF FILE
 ****************************************************************************
 */