Cyber Security

I n the previous chapter, we discussed the introduction part of cryptography and we understand the eras of cryptography. Today we are going to learn about the ancient cryptography era . Greece T he “Scytale” is the first cryptographic method that we can find when we analyze history. It was used in Greece in about 500 B.C which was developed by Spartans to send and receive secret messages. It is a device like a cylinder. And a strip of parchment uses to write messages on it as wounds in parchment. Once we remove the parchment it becomes an unclear message which is difficult to understand. So, to receive the exact message we should have the same size cylinder. It is a method that is considered as a type of transposition cipher. The problem with this method is there should be the same size cylinder.                                         Figure 1 - Scytale Rome B ut we consider Caesar cipher as the well-organized oldest cryptographic method which has been used in Rome by the empire Juli

What is cryptography A s human beings, we do not prefer to reveal our secret and private communication to outsiders. Because of that we usually send our letters inside an envelope to make sure that the contents of those letters should not disclose to unwanted people until the right persons get them. Likewise, we use the methodology of "cryptography" to ensure the secrecy of our data through online communication. This cryptography method ensures the basic features of secure data communication such as confidentiality, integrity, and authorization. Normally we define cryptography as the study and practice of hiding information from unauthorized persons. This ensures the confidentiality of data by restricting unauthorized persons to our data, ensure the integrity by using the hash functions which can detect whether our data was modified by someone or not, and it ensures authorization and non-repudiation. these are the benefits of cryptography. B efore centuries ago, people felt t

when we look at the annual budget of each and every country we can see all the countries give their first priority for the security of their country. Likewise, all of us give first priority to the security of our lives. But always these kinds of non-functional features are value-added things. Because of that, we had to invent more money for security features. so, this is a brief explanation about the security. After the beginning of the 21st century, we can see there was a massive growth of the internet and information communication. And lots of people try to share their valuable and secret information through the internet. because of that the crimes related to this information communication increased day by day. At the initial point of these activities, the related authorities could not be able to do any kind of an action because it was new to them. But after a few years, the developed countries give their concern about this problem. Because it was very important for them to communica