reading-notes

reading notes for code fellows

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Cryptography

cryptography is a major part of almost all internet interactions, and as such it is important to understand it.

Encryption, Decryption, and Cracking

One of the earliest encryption techniques is the Caesar Cipher, which was invented by Julius Caesar, and is a simple substitution cipher which replaces each original letter with a different letter in the alphabet by shifting it a certain amount. Julius usually used a shift of 3, but if someone who didn’t know that intercepted a message, they would need to attempt to ‘crack’ the cipher. The three main techniques that could be used are:

• frequency analysis - in general, languages will use some letters more frequently than others, like ‘e’, which allows us to analyze the frecuency of characters in the message and identify the most likely ‘e’ and narrow down shift possibilities
• known plaintext - the original message is known as plaintext, and knowing any part of the plaintext will make it easier to crack the rest of the encrypted version
• brute force - there are only 25 possible shifts. If all else fails, you could try each one until something yields a reasonable message.

Encryption is scrambling the data, decryption is recovering the original data using the key, and cracking is uncovering the original data without knowing the key.

Things I Want to Know More About

How much harder is it to crack a symbol replacement code than a Caesar Cipher?

Discussion

I think the different types of encryption and decryption through the internet are very interesting. I used to do manual code breaking, and I can’t even imagine how much easier it would be with a computer, but even so it seems like some codes are too tough to crack, even with computer algorithms.

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