Net Gap among Different Security Level Networks

High security level network is always physically isolated from other networks, but also has difficulty in information transmission. Net Gap keeps different networks cut, and transmitted information from high security network to low. It uses QR code to carry data, and keeps information transfer unilaterally. MD5 algorithm is used in digital signature and RSA arithmetic is used encoding and decoding process. Experiments approve its efficiency and security. The system is in high security and utility.