The name `` RC4 '' is trademarked , however . RC4 is often referred to as `` ARCFOUR '' or `` ARC4 '' ( meaning Alleged RC4 , because RSA has never officially released the algorithm ) , to avoid possible trademark problems . The name `` RC4 '' is trademarked , so RC4 is often referred to as `` ARCFOUR '' or `` ARC4 '' ( meaning Alleged RC4 ) to avoid trademark problems .