Try this:
base64_decode — Decodes data encoded with MIME base64
PHP: base64_decode - Manual
Usage:
string base64_decode ( string $data [, bool $strict= false ] )
data - The encoded data.
strict - Returns FALSE if input contains character from outside the base64 alphabet.
PHP Code:
$str = 'VGhpcyBpcyBhbiBlbmNvZGVkIHN0cmluZw==';
echo base64_decode($str);
?>
You might also use this regular expression:
^[a-zA-Z0-9/+]*={0,2}$
Which will also detect the usage of = or == at the end of the string (and only end). A function geared specifically toward this:
PHP Code:
<?php
function is_base64_encoded()
{
if (preg_match('%^[a-zA-Z0-9/+]*={0,2}$%', $data)) {
return TRUE;
} else {
return FALSE;
}
};
is_base64_encoded("iash21iawhdj98UH3"); // true
is_base64_encoded("#iu3498r"); // false
is_base64_encoded("asiudfh9w=8uihf"); // false
is_base64_encoded("a398UIhnj43f/1!+sadfh3w84hduihhjw=="); // true
?>