test script to find the correct method

test.php

<?php

$data = "123456";
$key = "17839778773fadde0066e4578710928988398877bb123789";
$options = 0;
$key = pack("H*", $key);

foreach (openssl_get_cipher_methods() as $method)
{
    $enc = @openssl_encrypt($data, $method, $key, $options);
    $dec = @openssl_decrypt($enc, $method, $key, $options);

    if ($enc == 'Ja79hWTRfBE=' && $dec == $data) {
        echo $method;
        break;
    }
}