AES 256 CTR based on AES 256 ECB on PHP

aes-ctr-256.php

<?php
function bin2text($binary)
{
	return implode(" ", str_split(bin2hex($binary), 32));
}
function aes_256_ctr($data, $key, $iv, &$counter = 0)
{
	assert(strlen($data)%32 == 0);
	assert(strlen($iv) == 16);
	assert(strlen($key) == 32);
	$res = "";
	$chunks = str_split($data, 32); //256 bit blocks
	foreach ($chunks as $chunk)
	{
		// Construct 256 bit $nonce_with_counter
		$nonce_with_counter = "";
		for ($j=0; $j<2;++$j)
		{
			$nonce = $iv;
			$add = $counter;
			// adding counter to nonce
			for ($i=15; $i>=0 and $add; --$i)
			{
				if (ord($nonce[$i]) + $add >= 256)
				{
					$t = (ord($nonce[$i]) + $add);
					$nonce[$i] = chr( $t%256 );
					$add = (int)($t/256);
				}
				else
				{
					$nonce[$i] = chr( ord($nonce[$i]) + $add);
					$add = 0;
				}
			}
			$counter++;
			$nonce_with_counter.=$nonce;
		}

		$ecb = openssl_encrypt($nonce_with_counter, 'aes-256-ecb', $key, OPENSSL_RAW_DATA | OPENSSL_NO_PADDING);
		$res .= ($ecb ^ $chunk);
	}
	return $res;
}


// Testing:

$data = 'A000000000000000000000000000000000000000000000000000000000000000'
 . 		'0000000000000000000000000000000000000000000000000000000000000000'
 ;
$data=hex2bin($data);
$data = random_bytes(32*100);

$iv = 'A000000000000000000000000000000A'; // 16 bytes
$iv = hex2bin($iv);
$iv = random_bytes(16);

$key = 'A000000000000000000000000000000000F00000000000000000000000000000'; //32 bytes
$key = hex2bin($key);

$key = random_bytes(32);
$ctr = openssl_encrypt($data, 'aes-256-ctr', $key, OPENSSL_RAW_DATA | OPENSSL_NO_PADDING, $iv);
$custom_ctr = aes_256_ctr($data, $key, $iv, $counter);

echo bin2text($custom_ctr), PHP_EOL;
echo "Should be:\n";
echo bin2text($ctr), PHP_EOL;

var_dump($custom_ctr==$ctr);