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Cryptography
Introduction
EncryptionThe art (or science) of putting messages into
a code, and the study of those coding techniques.
DecryptionThe 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