Best way to use PHP to encrypt and decrypt passwords? [duplicate]

Answer 1

Securiy Warning: This code is insecure. In addition to being vulnerable to chosen-ciphertext attacks, its reliance on unserialize() makes it vulnerable to PHP Object Injection.

To handle a string / array I use these two functions:

function encryptStringArray ($stringArray, $key = "Your secret salt thingie") {
 $s = strtr(base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, md5($key), serialize($stringArray), MCRYPT_MODE_CBC, md5(md5($key)))), '+/=', '-_,');
 return $s;
}

function decryptStringArray ($stringArray, $key = "Your secret salt thingie") {
 $s = unserialize(rtrim(mcrypt_decrypt(MCRYPT_RIJNDAEL_256, md5($key), base64_decode(strtr($stringArray, '-_,', '+/=')), MCRYPT_MODE_CBC, md5(md5($key))), "\0"));
 return $s;
}

It's flexible as in you can store/send via URL a string or array because the string/array is serialzed before encryption.