Substitution ciphers
Have you ever played a secret code game with your friends where you replaced each letter of the alphabet with a different letter? That's called a substitution cipher!
In a substitution cipher, you take each letter of a message and replace it with a different letter. This makes the message look like gibberish to anyone who doesn't know the code.
For example, let's say you want to send a secret message to your friend that says "HELLO". With a substitution cipher, you could replace H with X, E with M, L with Q, and O with P, so the message reads "XMQQP".
To decode the message, your friend would need to know what letters you used for each substitution. You could tell them the key (the letters you used for each substitution) in person, or write it down and give it to them.
Substitution ciphers can be fun to play with, but they're not very secure. Someone who knows you're using a substitution cipher could easily crack the code by figuring out the key. That's why substitution ciphers are usually used for fun and games, rather than for serious communication.
In a substitution cipher, you take each letter of a message and replace it with a different letter. This makes the message look like gibberish to anyone who doesn't know the code.
For example, let's say you want to send a secret message to your friend that says "HELLO". With a substitution cipher, you could replace H with X, E with M, L with Q, and O with P, so the message reads "XMQQP".
To decode the message, your friend would need to know what letters you used for each substitution. You could tell them the key (the letters you used for each substitution) in person, or write it down and give it to them.
Substitution ciphers can be fun to play with, but they're not very secure. Someone who knows you're using a substitution cipher could easily crack the code by figuring out the key. That's why substitution ciphers are usually used for fun and games, rather than for serious communication.
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