LXR uboot/lib/rc4.c

   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * (C) Copyright 2015 Google, Inc
   4 *
   5 * (C) Copyright 2008-2014 Rockchip Electronics
   6 *
   7 * Rivest Cipher 4 (RC4) implementation
   8 */
   9
  10#ifndef USE_HOSTCC
  11#include <common.h>
  12#endif
  13#include <rc4.h>
  14
  15void rc4_encode(unsigned char *buf, unsigned int len, const 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}
  49