Check if a string seems to be base64 encoded

is_base64.php

<?php
/**
 * @param   string  $str    
 * @return  bool
 */
function is_base64($str)
{
    return (bool)preg_match('`^[a-zA-Z0-9+/]+={0,2}$`', $str);
}

Regards.
I need just detect when a short string is encoded as base64, but your function no work:

    echo (bool)preg_match('`^[a-zA-Z0-9+/]+={0,2}$`', '4578');

Thanks

Maybe this better

<?php
function is_base64($str){
    if ( base64_encode(base64_decode($str, true)) === $str){
       return true;
    } else {
       return false;
    }
}

base64_encode("435435") does not return any "=" chars. So this function will not work for some input.

Maybe this better

string(4) "nope"
bool(true)

string(4) "nope" can be base64 decoded ... so it works if you base64 decode and reencode the input and check if they are the same :D

Use this:

if (base64_decode($mystring, true)) {
    // is valid
} else {
    // not valid
}

Use this:

if (base64_decode($mystring, true)) {
    // is valid
} else {
    // not valid
}

$mystring = 'aaa';
result is true

use this:

<?php

 $validB64 = preg_match("/data:([a-zA-Z0-9]+\/[a-zA-Z0-9-.+]+).base64,.*/", $base64_fille);

Maybe this better

<?php
function is_base64($str){
    if ( base64_encode(base64_decode($str, true)) === $str){
       return true;
    } else {
       return false;
    }
}

Thanks bro!!!!

function is_base64($str){
    if ( base64_encode(base64_decode($str, true)) === $str){
       return true;
    } else {
       return false;
    }
}

is_base64('Matthies') or is_base64('Barthels') return true

this is real name and function fails!!!!

function is_base64($str){
    if ( base64_encode(base64_decode($str, true)) === $str){
       return true;
    } else {
       return false;
    }
}

is_base64('Matthies') or is_base64('Barthels') return true

this is real name and function fails!!!!

@desaikalpesh34 I believe this solve your problem and mine!

private function isBase64Encoded(string $s) : bool
    {
        if ((bool) preg_match('/^[a-zA-Z0-9\/\r\n+]*={0,2}$/', $s) === false) {
            return false;
        }
        $decoded = base64_decode($s, true);
        if ($decoded === false) {
            return false;
        }
        $encoding = mb_detect_encoding($decoded);
        if (! in_array($encoding, ['UTF-8', 'ASCII'], true)) {
            return false;
        }
        return $decoded !== false && base64_encode($decoded) === $s;
    }

mariojrrc

Dude.. i've searched far and wide - and your solution is the only one that "TRULY" works..
Thanks mate!

Glad to help! @colzzky :)

Maybe this better

<?php
function is_base64($str){
    if ( base64_encode(base64_decode($str, true)) === $str){
       return true;
    } else {
       return false;
    }
}

Thanks bro!!!!

Perfect

None of the answers worked for me. In my case it was the lack of spaces that I used to tell if it was base64 encoded
$teststring = substr($string,4,100);
$not64 = strpos($teststring," ");
It's not in a function, but it has worked for me. I'm sure people will tell me that it won't always work, but ALL of the functions suggested above returned false for me regardless of the string.