Summary

Every day, more and more services are being added to our infrastructures, homes, and businesses, making network security a constant challenge. However, a secure network is important as it protects the organization. In this chapter, we took a look at the threats to our data that exist, which makes securely managing a large volume of data in various locations a challenge. We saw the importance of providing security services such as confidentiality, integrity, and availability, and how using cryptographic techniques can help protect those services.

We then took a look at some common cryptographic concepts, such as TTPs and key management using the PKI. We also got to know characters such as Bob, Alice, Trent, and Mallory, which help us to personalize and better understand complex cryptographic concepts. Finally, we took a look at two basic cryptographic concepts, substitution, and transposition. We saw how substitution substitutes plaintext characters with other characters to convert it into ciphertext. We also learned how transposition rearranges the characters of plaintext to conceal information. We then saw how we can use letter frequency analysis to crack a simple code, that uses a monoalphabetic cipher.

So that you can better understand the evolution of encryption, the next chapter will start with a review of some classical ciphers such as the Vigenère and Caesar ciphers. Then we'll examine how war efforts prompted the encoding of transmissions, and how the Enigma was used to securely send messages. We'll then learn the beginnings of the Data Encryption Standard (DES), with the development of Lucifer and Feistel ciphers, as scientists recognized the need to secure digital data.