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Learn the art of putting messages into a code and the study of coding techniques, including simple techniques like reversing, shifting, flipping, and the Caesar cipher. Explore examples of cryptography, public key encryption, digital signatures, and the use of PGP technology.
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Introduction • Encryption • The art (or science) of putting messages into a code, and the study of those coding techniques. • Decryption • The means by which to bring out the meaning from a coded message.
Simple Techniques • Original text “testing” • Reversing text • “gnitset” • Shifting text • “uftujoh” • Flipping text • “ettsnig” • Caeser cipher • Multi-shift (this one is by 2) • “vguvkpi” • Examples
Cryptography • Public Key Encryption • You create a private key/public key pair • If a message is encrypted with your private key, only your public key will decrypt it • Publish your public key on web sites or send it to people via e-mail • Uses • If you want to send a private message to another person, encrypt it with their public key (only they can decrypt it with their private key) • Digital Signatures • Encrypt with your private key first and then their public key • PGP (Pretty Good Privacy) • One version of this technology • Example