This section is concerned with two very powerful elements of the proofmaking arsenal: “Parity” is a way of referring to the result of an even/odd calculation; Counting arguments most often take the fo...This section is concerned with two very powerful elements of the proofmaking arsenal: “Parity” is a way of referring to the result of an even/odd calculation; Counting arguments most often take the form of counting some collection in two different ways – and then comparing those results. These techniques have little to do with one another, but when they are applicable they tend to produce really elegant little arguments.
Suppose Alice and Bob never had a chance to meet in person, and they nevertheless want to exchange messages which will be secret from Eve. What can they do? This section discusses symmetric ciphers, a...Suppose Alice and Bob never had a chance to meet in person, and they nevertheless want to exchange messages which will be secret from Eve. What can they do? This section discusses symmetric ciphers, asymmetric ciphers, cryptographic salt, and the RSA cryptosystem.
