Is string base 64 encoded?

Question

How can I find whether a string is a data encoded with base64_encode() function or not?

Is it possible?

Answer 1

Attempt to decode it strictly against the Base64 alphabet. The second parameter allows you to enforce this strict check; by leaving it out, the decoding function simply strips out illegal characters before decoding:

if (base64_decode($str, true) === false)
{
    echo 'Not a Base64-encoded string';
}