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is the science of encoding a message into a form that is unreadable and making sure only the proper people are capable of decoding the message back into its original form. This is usually done by using an encryption algorithm and a decryption algorithm (these two ....

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.... safe. The sender and the receiver then usually agree on a new key to prevent any further damage. In ancient Greece, around 550 Bc, messages were sent encoded to generals and could only be decoded using special staff keys. The key actually consisted of a physical object, which was applied on the message to get the decrypted version of it. In 50 Bc., one of the most simple cryptographic algorithms ever used was the one called the Caesar cipher, that was used by Julius Caesar to send messages to his generals. It consisted simply of switching each letter with the letter that was 3 letters further down the alphabet. For example "Stephen" would become " ....