How to Encrypt and Decrypt text?

[paispatin]

Dear all,

What should I do to encrypt and decrypt any text with simple PHP function?

I could encrypt any text with this function:
$mytext="what";
$encrypt_text=md5($mytext);
or
$encrypt_text=trim($mytext);
Well, how to decrypt this function?
Maybe anyone could give other function to encrypt and decrypt the text?

Thank you in advance

 

[sleipnir214]

You can't decrypt MD5. MD5 is not an encryption algorithm, but rather a hashing algorithm. It was designed to be a one-way cypher.


trim()? That function just removes whitespace from the beginnings and ends of strings. It's not any kind of cypher at all.

I recommend you start by taking a look at the mcrypt function family documentation in the PHP online manual:

http://www.php.net/manual/en/ref.mcrypt.php

Want the best answers? Ask the best questions:

http://www.catb.org/~esr/faqs/smart-questions.html

TANSTAAFL!!

 

[hos2]

for encrypting and decrypting I use the following functions

function encrypt($key, $plain_text)
{
// returns encrypted text
// incoming: should be the $key that was encrypt
// with and the $plain_text that wants to be encrypted

  $plain_text = trim($plain_text);

  /*
     We need a way to generate a _unique_ initialization vector
     but at the same time, be able to know how to gather our IV at both
     encrypt/decrypt stage.  My personal recommendation would be
     (if you are working with files) is to get the md5() of the file.
     In this example, however, I want more of a broader scope, so I chose
     to md5() the key, which should be the same both times. Note that the
IV
     needs to be the size of our algorithm, hence us using substr.
  */

  /* generate an initialization vector */
  $iv = substr(md5($key), 0,mcrypt_get_iv_size
(MCRYPT_CAST_256,MCRYPT_MODE_CFB));
  /* now we do our normal encrypting */ 
  $c_t = mcrypt_encrypt (MCRYPT_CAST_256, $key, $plain_text,
"cfb", $iv);

    return trim(chop(base64_encode($c_t)));
}

function decrypt($key, $c_t)
{
// incoming: should be the $key that you encrypted
// with and the $c_t (encrypted text)
// returns plain text

  // decode it first :)
  $c_t =  trim(chop(base64_decode($c_t)));

  /* generate an initialization vector */
  $iv = substr(md5($key), 0,mcrypt_get_iv_size
(MCRYPT_CAST_256,MCRYPT_MODE_CFB));
  /* now we do our normal decrypting */ 
  $p_t = mcrypt_decrypt (MCRYPT_CAST_256, $key, $c_t, "cfb",
$iv);

return trim(chop($p_t));
}

I found these functions at

http://www.php.net

and they work fine for me