What is Cryptography in Computer Network?

In this tutorial, we are going to see What is Cryptography in Computer Network? Humans have always had the urge to hide information, even before computers and calculating machines were invented.

The Internet has evolved so much since its creation that it has become an essential communication tool. However, this communication increasingly involves strategic issues related to business activity on the Web. The transactions made through the network can be intercepted, especially since the laws are difficult to set up on the Internet, so it is necessary to guarantee the security of this information, it is the cryptography that takes care of it.
 

 

What is Cryptography in Computer Network?

The word cryptography is a generic term for all the techniques used to encrypt messages, which means making them unintelligible without specific action. The word encrypt is sometimes used, but we prefer the word cipher.

Cryptology is essentially based on arithmetic: in case of a text, it is a question of transforming the letters which compose the message into a succession of figures (in form of bits in case of data processing because computers are based on binary), then to make calculations on these figures to :

• to modify them in such a way to make them incomprehensible. The result of this modification (the encrypted message) is called a ciphertext as compared to the initial message, called a plaintext;
• to ensure that the recipient will be able to decipher them.

Encoding a message in such a way as to make it secret is called Encryption. The reverse method, which consists in finding the original message, is called Decryption.
 

^{Image source: https://commons.wikimedia.org/wiki/File:Encryption1.png}
 
 
Encryption is generally done with an encryption key, while decryption requires a decryption key. There are generally two types of keys:

• Symmetric keys: these are keys used for encryption as well as for decryption. This is called symmetric encryption.
• Asymmetric keys: these are keys used for asymmetric encryption (also called public key encryption). In this case, a different key is used for encryption and for decryption

When the decryption key is not known to the attacker, it is called cryptanalysis or cryptoanalysis (the more familiar term of “cracking” is also often used).

Cryptology is the science that studies the various scientific aspects of these techniques, which means that it covers Cryptography and Cryptanalysis.
 

The purpose of Cryptography:

Cryptography is traditionally used to hide messages from the eyes of certain users. Today, this use has an even greater advantage since communications via the Internet circulate in infrastructures whose reliability and confidentiality cannot be guaranteed. Cryptography is now used not only to protect the confidentiality of data but also to guarantee its integrity and authenticity.
 

 

Cryptanalysis

Cryptanalysis is the process of rebuilding an encrypted message in clear text using mathematical methods. Thus, any cryptosystem must necessarily be resistant to cryptanalysis methods. When a cryptanalysis method allows decrypting a message encrypted with a cryptosystem, we say that the encryption algorithm has been “broken”.
 
Computer Network MCQ – Questions and Answers – Part 1Networking MCQs questions with answers to prepare for exams, tests, and certifications. These questions are taken from a real written exam and some parts are…Read More