CAESAR’S & VIGENÈRE | CIPHERS | CRYPTOGRAPHY
Caesar, Vigenère, and a Lesson in Basic Cryptography
Exploring two historical ciphers and how they paved the way for modern encryption.
From Ancient Rome to modern cybersecurity, cryptography has been a cornerstone of secure communication for millennia, and today, we’ll take a look at some of history’s most well-known cryptographic methods.
In this article, we will explore two historical ciphers: Caesar’s Cipher and the Vigenère Cipher, mainly tackling the former, and comparing them.
The Caesar Cipher
The Caesar Cipher is one of the first examples of cryptography being used to protect communications and, in those days especially, soldiers’ lives.
This is what’s known as a substitution cipher, meaning that each character of a text has a correspondent character.
This specific cipher involves shifting the alphabet a certain number of letters either to the left or to the right depending on your preference.
For example, for a key of 3 — or the number of shifts — and shifting left, by shifting the text for Hello we get Ebiil.
Here’s a little challenge for you, try to decode Khoor (Hint: shift 3 letters to the left this time). You can share your answers in the comments!
Alphabet Shifts (Examples)
In order, the right-shifted alphabet with a key of 3 is:
- D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, A, B, C,
- This alphabet was right shifted 3 times (a key of value 3).
In order, the normal English alphabet is:
- A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z
In order, the left-shifted alphabet with a key of 3 is:
- X, Y, Z, A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W
- This alphabet was left shifted 3 times (a key of value 3).
The Vigenère Cipher
This 15th century cipher first described by Leon Battista Alberti is a big step up from the former in terms of security.
We won’t go in-depth on this cipher’s algorithm, just know that it is significantly more secure, using a key made up of letters (possible combinations for the key are 26^n with n representing the length of the key) rather than the number of letters in an alphabet (only 26 combinations).
Using this cipher, we can encrypt the string Hello, World! using the key PASS to get Weddd, Wgjad!
As you can see, this even looks harder than Caesar’s. Given that the letters are no longer tied to one specific correspondent but rather the ciphertext is determined by a combination of the key and the plaintext.
This cipher has been used before in actual combat. Notably, the Confederate States of America used a version of it to encrypt its communications, but the fact they only used a few different keys during the whole war meant that the Union was able to break their codes most of the time.
Caesar v. Vigenère, The Key Differences
The Vigenère Cipher, with its more complicated nature, is a great way to encrypt information you don’t want to be understood, although it is itself very vulnerable given a bit of time.
Caesar’s Cipher, although much less sophisticated and much easier to crack, has become an entry point for many enthusiasts into cryptography, mainly due to its increased popularity due to shows like Gravity Falls and different internet mysteries which have garnered it popularity.
From Ancient Rome to 15th century France, Nazi Germany’s Enigma and, today, ciphers like the AES256 encryption standard, cryptography has come a very long way, and it will only get better as old methods begin to show their cracks.
To wrap things up, I would like you, the reader, to try and encrypt some messages using these two ciphers. Maybe leave them in the comments down below too and see if others can decrypt them.
