CAMBRIDGE IGCSE Topic 2.3 Symmetric and asymmetric encryption Also in this topic... CAMBRIDGE IGCSE Topic 2.1 Packets and packet structure CAMBRIDGE IGCSE Topic 2.1 Packet switching CAMBRIDGE IGCSE Topic 2.1 Universal Serial Bus (USB) CAMBRIDGE IGCSE Topic 2.2 The need for error checking CAMBRIDGE IGCSE Topic 2.2 Check digits