Security measures Computer networks 13 Computer security 8 Mobile communication systems 7 Wireless communication systems 7 Access control 6 Intrusion detection systems (Computer security) 5 Mobile computing 5 Public key infrastructure (Computer security) 5 Information storage and retrieval systems 4 Multimedia systems 4 Cell phones 3 Data protection 3 Cell phone systems 2 Cryptography 2 Data encryption (Computer science) 2 Digital techniques 2 Digital watermarking 2 Electronic mail systems 2 Equipment and supplies 2 Machine learning 2 Medical informatics 2 Medical records 2 Multicasting (Computer networks) 2 Prevention 2 Telecommunication 2 Wireless LANs 2 Audio frequency 1 Biometric identification 1 Bluetooth technology 1