In this lab, you will learn about security risks on the Internet and how data can be encoded to protect it.

On this page, you will learn different ways of encoding and decoding a message.

  1. Write a secret message to send to a partner. Invent some way of encoding the message. Then send the encoded message to your partner.
  2. Your partner will send you an encoded message. When you get it, try to decode it. What strategies are you using to decode it?
  3. Talk with Another PairWith another pair of students, compare the methods you used to encode your messages. Was anyone able to decode their message? How?

Cryptography is the study of how to convert messages into code (encryption) and how to solve codes (decryption). Just as TCP enables reliable transmission over an unreliable network, cryptography enables verifiable, secure transmission over an insecure network.

A secure transmission can't be read if it is intercepted.

A verifiable transmission is guaranteed to be from the person it claims to be from.

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Cryptography is the methods for encoding and decoding messages.

Symmetric cryptography uses the same secret key to encode and to decode a message. Symmetric cryptography has been around for thousands of years. The trouble with symmetric cryptography is that the key becomes another message that needs to be transmitted securely.

Public key (asymmetric) cryptography was created by mathematicians in the 1970s. It uses two different keys for encryption and decryption, so sharing the public encryption key doesn't give away the private decryption key. Public key encryption is the primary method of encryption today because of its high level of security.

Brian wants to discuss having these as white text for the sake of beauty and joy. --MF, 1/26/18
Read this comic by Randall Munroe (source: XKCD). Talk with Your Partner What's the joke?
XKCD: Public Key