Type in a message, then a key, and Scratch Cat will output the enciphered message! For those of you who don't know, the Caesar Cipher is named after Julius Caesar, who at various times acted as a general, a consul, a proconsul, a pontifex maximus, a dictator, and a dictator for life. He was famously assassinated in 44 B.C. on the Ides of March, aka March 15. Before that, as a general, he used this basic cipher to encode messages to his army. This cipher of his is very simple, but it was hard to crack for enemies who had never heard of alphabet-shifting. The way the Caesar Cipher works is that it shifts letters forward in the alphabet. As an example, say that you had the message CAT, and a key of 3. C is the third letter in the alphabet. With a key of 3, you would add 3 to that index, resulting in 3+3=6. The sixth letter in the alphabet is F, so the first letter of the enciphered (or encoded) message is F. You can also count forward 3 letters from C: D, E, F. Similarly, the next letter is A, the first letter in the alphabet, so the next enciphered letter is D, and the last enciphered letter is W. So encrypting CAT with a key of 3 gives FDW. To decrypt the message, you use the same key. If you have FDW and you know that the key used to encrypt it was 3, you can subtract from the letters. F is the sixth letter, and 6-3=3, so the first letter of the decrypted message is C, the third letter of the alphabet. You can also count backward 3 letters from F: E, D, C. In a similar manner, you can decrypt the rest of the simple word and get CAT. If you only have an encrypting program, you can also add -3 to the letters' indexes (or indices). Adding -3 is the same thing as subtracting 3. While this is a very easy cipher to use on your own, it's often faster to use a computer if you have long messages. Credit to Julius Caesar and the sources of the citations below. Made alone. N.B.: Case sensitivity is broken. The program only works on the Latin alphabet for the 26 letters used in English (abcdefghijklmnopqrstuvwxyz). Special characters & other letters are not encrypted. This is compatible with other programs to decrypt/encrypt the Caesar cipher. N.B. 2: N.B. stands for "nota bene", Latin for "note well." Citations (MLA)* "Julius Caesar." Wikipedia, Wikipedia Foundation, 20 March 2024, https://en.wikipedia.org/wiki/Julius_Caesar. Schwartz, Ella. Can You Crack the Code?: A Fascinating History of Ciphers and Cryptography. New York City, Bloomsbury Publishing Plc, 2019. _____________________________________________ *I can't use italics on this website. Therefore, italics have been omitted, although it would have been more correct to include them in some places, according to online style guides.
