Imagine that you want to meet up with some friends at a cool party tonight. You send a text message in the group chat containing the specific details of where/when to go. You excitedly pace around your house while thinking about how much fun you’re going to have. After arriving at the party, you wait for your friends to come. They never do. What’s going on? You call one of your friends, only for him to respond that the message he had received said that the party would start tomorrow! Your message had been intercepted and modified by someone else! (maybe a jealous coworker or an internet prankster?). Obviously this scenario is very unlikely in the modern world, but it shows the importance of shielding information from a hostile third party. Without any sort of privacy or protection when sending or receiving information, there would be much worse consequences than just not being able to meet up with your friends at a party. Cryptography is humanity’s solution to this problem. What is cryptography? Cryptography is an extremely important component of our modern day life and is heavily utilized in many different places such as on the internet, through sending emails, accessing websites (HTTPS protocol) and many other applications. Cryptography can be described as the bedrock of internet security.
Cryptography is a field with a long history that generally focuses on the study of securing the information that you send and receive in order to prevent unauthorized third parties from stealing or compromising its integrity.
In order to better understand cryptography, a few key terms must be defined.
(The following terms apply to classic cryptography)
Encryption:
Encryption is the process of scrambling information in order to prevent an unauthorized third party from being able to access.
Decryption:
Decryption is the process of recovering information from the scrambled data in such a way such that only the intended recipient is able to obtain the desired information.
Key:
The key is essentially a piece of information that the intended receiver has access to that will help this intended receiver quickly and successfully decrypt an encrypted message.
While the study of cryptography involves many complex and interesting algorithms and structures, let’s start off with a relatively simple cipher(an algorithm for encrypting and decrypting information). The Caesar Cipher, often referred to as a “shift” or a “substitution cipher”, is a very interesting case study. The Caesar Cipher was supposedly used, as the name should suggest, by Julius Caesar and his armies to carefully send and receive critical battlefield information to and from the troops. The Cipher worked in a relatively simple manner. Each character in an initial message would be shifted to the right by some amount, let’s say five for this example. So if the letter “A” showed up in a message, we could shift it 5 spots to the right and replace it with an “F”. If the letter “Z” was in a message, you could still shift it 5 spots to the right by shifting it cyclically. Essentially, view the alphabet as a connected loop with the letter “Z” pointing back to “A”. Then moving 5 spots to the right gives us: Z -> A -> B -> C -> D -> E. Following this process, the whole message would thus be encrypted(try to remember what this means!). If the general receiving this information knew the key beforehand, then he would be able to successfully decrypt this information and recover valuable military intel. And if enemies were able to messengers transporting encrypted information, they would be unlikely to recover any useful information. While the Caesar cipher can very easily be overcome by a third party (by simply brute forcing all possible shifts), it is still a great introduction to the topic of cryptography. While the Caesar Cipher worked well for the Romans, we’ve since been able to design and implement much more secure encryption techniques that aren’t as easily broken. In its simplicity, the Caesar Cipher makes a great first introduction to the study of cryptography.
Modern cryptography combines principles of both mathematics and computer science to make algorithms that have not been broken for many years. I gives The internet can essentially be viewed as a much more complex and powerful version of our initial problem: sending a package safely to a friend.. Modern cryptography techniques have provided an effective way for packets of information to be encrypted and decrypted efficiently while also remaining protected from nefarious third party actors.
Sources:
https://www.geeksforgeeks.org/caesar-cipher-in-cryptography
https://www.fortinet.com/resources/cyberglossary/what-is-cryptography
https://www.cloudflare.com/learning/ssl/what-is-encryption
https://ghostvolt.com/articles/cryptography_history.html
https://www.hypr.com/security-encyclopedia/cipher
https://www.britannica.com/topic/cryptographic-key
https://www.sciencedirect.com/topics/computer-science/symmetric-cryptography
https://www.techtarget.com/searchsecurity/definition/asymmetric-cryptography