Simple PHP Encrypt, Decrypt

Simple php encryption

function encrypt($data, $salt='!kQm*fF3pXe1Kbm%9') {
    $key = hash('SHA256', $salt, true);
    srand(); $iv = mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC), MCRYPT_RAND);
    if (strlen($iv_base64 = rtrim(base64_encode($iv), '=')) != 22){
        return false;
    }

    $encrypted = base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $data . md5($data), MCRYPT_MODE_CBC, $iv));
    return $iv_base64 . $encrypted;
}

function decrypt($cypher, $salt='!kQm*fF3pXe1Kbm%9') {
    $key = hash('SHA256', $salt, true);
    $iv = base64_decode(substr($cypher, 0, 22) . '==');
    $encrypted = substr($cypher, 22);
    $decrypted = rtrim(mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, base64_decode($encrypted), MCRYPT_MODE_CBC, $iv), "\0\4");
    $hash = substr($decrypted, -32);
    $decrypted = substr($decrypted, 0, -32);
    if (md5($decrypted) != $hash) return false;
    return $decrypted;
}