Part one---Why do we need to learn cryptography

Now is a time which the information is extremely development. A lot of datas are stored by the form of electronic messages. The transmission of the information is often through electronic medium such as mobile phone communication, electronic commerce, the on-line chat service etc. Unfortunately, those way of transmit the information are not safe. The message that we delivered is possible be stolen or monitored. If we have no appropriate protect measure, so once the important messages leaks out, the result may be inconceivable.

The safe protection system of any rank all may introduce the concept of encryption. The data encryption has the very vital significance to the network correspondence and the data storage, it can play an important role of keep the data security, authenticate message, maintain the integrity of data and anti- denial.

That's why we should...