Certified Information Systems Security Professional (CISSP) Practice Exam 2025 – All-in-One Guide to Mastering Your Certification!

A Jefferson Disk is a cryptographic device that utilizes a series of rotating disks or wheels, each inscribed with letters of the alphabet. This device was invented by Thomas Jefferson as a means to encrypt messages during the American Revolution. The operation of the Jefferson Disk involves arranging the disks in a specific order to create a cipher. When encoded, the letters on different disks can produce a seemingly random sequence of characters, making it much harder for unauthorized individuals to decipher the message without knowledge of the specific arrangement of the disks.

The design allows for a high degree of security by making it necessary to know both the order of the disks and their positions to decrypt the message. It serves as an example of early attempts at creating strong encryption methodologies using mechanical devices. This showcases how cryptography has evolved over time, moving from mechanical methods to modern digital encryption techniques.