1. Applying the modern cryptographical technology constructs two digital copyright protection schemes.

2. VPN cryptographical system is concerned with cryptographical technology, authentication technology and VPN implementation protocols.

3. How to complete an unfinished magic square and how to separate the modulus sum of magic squares are new problems with cryptographical significance in magic square.

4. In modern cryptography, it is believed that any algorithm of encryption and decryption in cryptographical systems can be open, their safety depends on key security.

5. The problem of digital copyright protection is taken into account by more and more people. Cryptographical technology is one of the key solutions to this problem.

6. It is believed that in modern cryptography, any algorithm of encryption and decryption in cryptographical systems could be public, and the security should rely on the secure key.