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PHP implements rc4 encryption algorithm

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Release: 2016-07-25 09:09:32
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The decryption method of this algorithm is to re-encrypt once and then it can be restored. .

  1. /*
  2. * rc4 encryption algorithm
  3. * $pwd key
  4. * $data data to be encrypted
  5. */
  6. function rc4 ($pwd, $data)//$pwd key $data needs to be encrypted string
  7. {
  8. $key[] ="";
  9. $box[] ="";
  10. $pwd_length = strlen($pwd);
  11. $data_length = strlen($data);
  12. for ($i = 0; $i < 256; $i++)
  13. {
  14. $key[$i] = ord($pwd[$i % $pwd_length]);
  15. $box[$i] = $i;
  16. }
  17. for ($ j = $i = 0; $i < 256; $i++)
  18. {
  19. $j = ($j + $box[$i] + $key[$i]) % 256;
  20. $tmp = $box[ $i];
  21. $box[$i] = $box[$j];
  22. $box[$j] = $tmp;
  23. }
  24. for ($a = $j = $i = 0; $i < ; $data_length; $i++)
  25. {
  26. $a = ($a + 1) % 256;
  27. $j = ($j + $box[$a]) % 256;
  28. $tmp = $box[$a ];
  29. $box[$a] = $box[$j];
  30. $box[$j] = $tmp;
  31. $k = $box[(($box[$a] + $box[$j ]) % 256)];
  32. $cipher .= chr(ord($data[$i]) ^ $k);
  33. }
  34. return $cipher;
  35. }
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