encrypt decrypt example using php-defuse

encrypt-decrypt-php-defuse.php

<?php

    // error checking
    ini_set('display_errors', 1);

    // require php-defuse.phar
    require_once('defuse-crypto.phar');

    use Defuse\Crypto\Crypto;
    use Defuse\Crypto\Key;
    use Defuse\Crypto\KeyProtectedByPassword;

    $phrase = 'Encrypt me peasant';
    $key_name = 'mykey';
    $pass = 'sample'; // this would be based on the user's actual password when they login, you store hashed pass so it's not related to that

    // dump unencrypted text

    echo $phrase . '<br><br>';

    // check memcache
    $server = 'localhost';
    if (!empty($_REQUEST['server'])) {
        $server = $_REQUEST['server'];
    }
    $memcache = new Memcache;
    $isMemcacheAvailable = @$memcache->connect($server);

    // check if key exists
    if ($isMemcacheAvailable) {

        // create key, assuming user doesn't have one yet
        $protected_key = KeyProtectedByPassword::createRandomPasswordProtectedKey($pass);
        $protected_key_encoded = $protected_key->saveToAsciiSafeString();

        $user_key = $protected_key->unlockKey($pass);
        $user_key_encoded = $user_key->saveToAsciiSafeString();

        $memcache->set($key_name, $user_key_encoded, 0, 86400); // set for 1 day, destroy on logout

    }
    else {
        // can't encrypt
    }

    // get key
    $user_key_encoded = $memcache->get($key_name);// ... get it out of the session ...
    $user_key = Key::loadFromAsciiSafeString($user_key_encoded);

    // encrypt the text
    $encrypted_phrase = Crypto::encrypt($phrase, $user_key);

    // dump encrypted text
    echo 'encrypted: ' . $encrypted_phrase . '<br><br>';

    // decrypt text
    try {
        $decrypted_phrase = Crypto::decrypt($encrypted_phrase, $user_key);
        echo 'decrypted: ' . $decrypted_phrase . '<br><br>';
    } catch (Defuse\Crypto\Exception\WrongKeyOrModifiedCiphertextException $ex) {
        echo "failed to decrypt";
    }