One Time Pad (OTP) encryption is the only proven unbreakable cryptographic system. It works by combining a randomly generated key pad with the plaintext message. Each letter is encrypted by adding it to the corresponding letter on the pad. To decrypt, the inverse is done by subtracting. OTPs must be used only once and then destroyed to maintain security. Examples are provided of encrypting and decrypting messages using an OTP to demonstrate how it works.

1. One Time Pad Usage (OTP) SSG Ryan J. Gomez – U.S. Army "If you think cryptography can solve your problem, then you don't understand your problem and you don't understand cryptography." -- Bruce Schneier

2. Terminal Learning Objective Terminal Learning Objective: Action: Correctly identify and utilize a OTP. Condition: Given a OTP, correct keying material, and scratch paper & writing utensil in a classroom environment. Standard: Decrypt and Encrypt a OTP message.

3. Safety, Risk, and Environmental Considerations Safety Requirements: None Risk Assessment: Low Environmental Considerations: None

4. Evaluation Evaluation: Show an understanding of OTP usage and productively participate in group discussion.

5. Enabling Learning Objective (ELO) ELO: Cryptology and History of OTP usage.

6. History of Cryptography and OTP Usage * The Earliest methods of cryptography were altered hieroglyphics attempting to pass secret messages. * WWII messages were primarily mechanically generated. * Modern cryptography utilizes mathematically based encryption.

16. One Time Pad The above is an example of a page from a standard one time pad. The encryption & decryption keys are impossible to decipher when generated using entirely random keys.