Bob as two people who want to communicate securely. Basic Encryption Given a message, m, an encryption algorithm, E, and a key Ke, produce a ciphertext, c, such that: c = E(Ke, m) Meet Eve. Eve is an eavesdropper. If Eve knows only c, she can’t recover m without Ke. Basic Decryption Given a ciphertext, c, decryption algorithm, D, and a key Ke, produce a message, m, such that: m = D(Ke, c) Josh Datko Developing the CryptoCape January 21, 2014 7 / 37