Cryptography
From the Simple English Wikipedia, the free encyclopedia that anyone can change
Cryptography is a science about how to keep information secret and safe. It has been used for over 2000 years. Cryptography is very important in computing and on the Internet.
When someone uses the Internet, other people may be able to read the messages that the person sends.
When a message is sent using cryptography, it is changed (or encrypted) before it is sent. The change makes the message hard to read. If someone wants to read it (or decrypt it), they need to change it back. How to change it back is a secret. Both the person that sends the message and the one that gets it should know the secret, but other people do not.
Normally, the changes of the message are done by a computer, because most cryptography involves hard math that computers are good at.
A simple form of cryptography is the Caesar cipher.
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