Cryptography Computer security 21 Data encryption (Computer science) 19 Coding theory 13 Security measures 11 History 10 World War, 1939-1945 9 Mathematics 8 Access control 7 Computer networks 7 Computers 6 Data protection 6 Ciphers 5 Foreign relations 5 Algebra, Boolean 4 Data processing 4 Computer algorithms 3 Digital watermarking 3 Electronic intelligence 3 Espionage, Soviet 3 Secret service 3 C++ (Computer program language) 2 Combinatorial designs and configurations 2 Communism 2 Computational complexity 2 Curves, Elliptic 2 Diplomatic history 2 Economic aspects 2 Fault-tolerant computing 2 Information theory 2