[thirdparty/u-boot.git] / lib / rc4.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * (C) Copyright 2015 Google, Inc
 *
 * (C) Copyright 2008-2014 Rockchip Electronics
 *
 * Rivest Cipher 4 (RC4) implementation
 */

#ifndef USE_HOSTCC
#include <common.h>
#endif
#include <rc4.h>

void rc4_encode(unsigned char *buf, unsigned int len, unsigned char key[16])
{
	unsigned char s[256], k[256], temp;
	unsigned short i, j, t;
	int ptr;

	j = 0;
	for (i = 0; i < 256; i++) {
		s[i] = (unsigned char)i;
		j &= 0x0f;
		k[i] = key[j];
		j++;
	}

	j = 0;
	for (i = 0; i < 256; i++) {
		j = (j + s[i] + k[i]) % 256;
		temp = s[i];
		s[i] = s[j];
		s[j] = temp;
	}

	i = 0;
	j = 0;
	for (ptr = 0; ptr < len; ptr++) {
		i = (i + 1) % 256;
		j = (j + s[i]) % 256;
		temp = s[i];
		s[i] = s[j];
		s[j] = temp;
		t = (s[i] + (s[j] % 256)) % 256;
		buf[ptr] = buf[ptr] ^ s[t];
	}
}
Commit	Line	Data
83d290c5	1	// SPDX-License-Identifier: GPL-2.0+
1acab96d SG	2	/*
	3	* (C) Copyright 2015 Google, Inc
	4	*
	5	* (C) Copyright 2008-2014 Rockchip Electronics
	6	*
	7	* Rivest Cipher 4 (RC4) implementation
1acab96d SG	8	*/
	9
	10	#ifndef USE_HOSTCC
	11	#include <common.h>
	12	#endif
	13	#include <rc4.h>
	14
	15	void rc4_encode(unsigned char *buf, unsigned int len, unsigned char key[16])
	16	{
	17	unsigned char s[256], k[256], temp;
	18	unsigned short i, j, t;
	19	int ptr;
	20
	21	j = 0;
	22	for (i = 0; i < 256; i++) {
	23	s[i] = (unsigned char)i;
	24	j &= 0x0f;
	25	k[i] = key[j];
	26	j++;
	27	}
	28
	29	j = 0;
	30	for (i = 0; i < 256; i++) {
	31	j = (j + s[i] + k[i]) % 256;
	32	temp = s[i];
	33	s[i] = s[j];
	34	s[j] = temp;
	35	}
	36
	37	i = 0;
	38	j = 0;
	39	for (ptr = 0; ptr < len; ptr++) {
	40	i = (i + 1) % 256;
	41	j = (j + s[i]) % 256;
	42	temp = s[i];
	43	s[i] = s[j];
	44	s[j] = temp;
	45	t = (s[i] + (s[j] % 256)) % 256;
	46	buf[ptr] = buf[ptr] ^ s[t];
	47	}
	48	}