Presents a public-key cryptosystem application to introduce students to several topics in discrete mathematics. A computer algorithms using recursive methods is presented to solve a problem in which one person wants to send a coded message to a second person while keeping the message secret from a third person. (MDH)

Introduces basic principles of coding and decoding including the use of letter frequencies to decode secret messages by using the radio premium codes of Little Orphan Annie and Dick Tracy. (KHR)

Described are some ways in which individual states code driver's license numbers. The encoding of month, date of birth, year of birth, sex, and others involving elementary mathematics and the use of an elaborate system of hashing functions in describing the first, middle, and last names are discussed. (KR)

Discusses the study of identification codes and check-digit schemes as a way to show students a practical application of mathematics and introduce them to coding theory. Examples include postal service money orders, parcel tracking numbers, ISBN codes, bank identification numbers, and UPC codes. (MKR)

Cryptography is the science that renders data unintelligible to prevent its unauthorized disclosure or modification. Presents an application of matrices used in linear transformations to illustrate a cryptographic system. An example is provided. (17 references) (MDH)