Certified Ethical Hacker (CEH) Study Guide

Chapter 11. Cryptography

Around 180 BC, the Greek philosopher and historian Polybius was busy rethinking government. He postulated such revolutionary ideas as the separation of powers and a government meant to serve the people instead of ruling over them. If this sounds familiar, it should: his work was foundational for later philosophers and writers (including Montesquieu), not to mention the US Constitution.

Considering the times he lived in, not to mention his family circumstances and upbringing, Polybius understandably wanted a little secrecy in his writing. His father was a Greek politician and an open opponent of Roman control of Macedonia. He was eventually arrested and imprisoned, and Polybius was deported to Rome, where he found work as a tutor. He eventually met and befriended a Roman military leader and began chronicling the events he witnessed in what would become known as The Histories, detailing Rome’s rise to power from 264 to 146 BC.

Even as he did all this historical writing, though, Polybius was his father’s son and continued writing about the separation of government powers and against the abuses of dictatorial rule. In an effort to keep this part of his writing secret, he came up with what has become known as the Polybius square. The idea was simple. First, create a grid with numbers running across the top and along the left side. Next, populate the interior with the letters of the alphabet. Then, when writing, a letter becomes its coordinates on the grid. ...