base64_decode — Decodes data encoded with MIME base64
string base64_decode ( string $data [, bool $strict = false ] );
$data - The encoded data.
$strict - Returns FALSE if input contains character from outside the base64 alphabet.
Returns the original data or FALSE on failure. The returned data may be binary.
<?php
$str = 'YmFzZTY0IGVuY29kZWQgc3RyaW5n';
echo base64_decode($str);
?>