<!-- Collection of code snippets by Arne Vajhøj -->
<!-- from articles on eksperten.dk / vajhoej.dk (2004-now) -->
<?php

// generate salt
function gen_salt($size) {
    return openssl_random_pseudo_bytes($size);
}

// hash: text -> Base64 text
// verify: text + saved hash -> true/false
function myhash($alg, $pw, $opt) {
    if(array_key_exists('salt', $opt)) {
        $saltlen = $opt['salt'];
        $opt['salt'] = gen_salt($saltlen);
    }
    return password_hash($pw, $alg, $opt);
}

function verify($pw, $savedhash) {
    return password_verify($pw, $savedhash);    
}

// test
define('PW', 'A super secret password');

function test($label, $alg, $opt) {
    echo $label . ":\r\n";
    $hashval = myhash($alg, PW, $opt);
    echo '  ' . $hashval . "\r\n";
    $ok = verify(PW, $hashval);
    echo '  ' . ($ok ? 'True' : 'False') . "\r\n";
    $ok2 = verify(PW + 'X', $hashval);
    echo '  ' . ($ok2 ? 'True' : 'False') . "\r\n";
}

test('BCrypt', PASSWORD_BCRYPT, array('cost' => 15, 'salt' => 32));
//test('Argon2i', PASSWORD_ARGON2I, array()); // require PHP 7.2+
?>