The connections between cryptanalysis and the decipherment of ancient languages. The author explores history---Caesar ciphers, substitution ciphers, cribs, machine ciphers like Enigma and Purple, Navajo code, and the ultimate crib---the Rosetta stone.

High powered mathematics and supercomputers join forces to attack problems in national security and terrorism. Scientists from Lawrence Livermore National Laboratory use supercomputers, differential equations, and attributed relational graphs to detect threatening behavior and create plans for safe keeping the country.

How accumulated round off error  lead to the failure of the Patriot missile defense system during the Gulf War.

Dudeney's classic "Send More Money" cryptarithmetic puzzle has a unique solution in base ten. This article generalizes explores solutions in bases other than ten.

Algorithmic thinking is likely to cause the most disruptive paradigm shift in the sciences since quantum mechanics. The  big ideas revolve around universality, duality, and self-reference.

With a special deck of cards based on the error-correcting Hamming code of length seven, you can detect a lie, if one exists.

Winners from the September 2005 contest---to pose a problem in such a way that they contained their own answers---include Raymond Greenwell, Roger Nelsen, Head-Royce School Math Club, Rheta Rubenstein, Dave Ehren, Jeff Tupper, and Stan Wagon.

To read this article we must swear you to secrecy. While cryptology is the bread-and-butter of the NSA's business, carrying out the mission requires the talent of many different kinds of employees: intelligence analysts, linguists, computer scientists, engineers, human resource specialists, and mathematicians. Read profiles of Paul Iezzi, Valerie Nelson, and Megan Waterman.

A different type of summer research experience.

Practical advice on preparing and delivering a PowerPoint presentation.

Elizabeth Russell review Coincidences, Chaos, and All That Math Jazz by Edward B. Burger and Michael Starbird and Natalya St. Clair reviews The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography by Simon Singh.

Climber Phil Hage climbs a natural saddle point in the Navajo Sandstone near Escalante, Utah.