Otpad

Otpad is a term used in cryptographic discussions to denote a One-Time Pad Application or Pad, referring to a software or hardware concept designed to manage and apply one-time pads for offline encryption. The core idea of a one-time pad is perfect secrecy: a random pad as long as the plaintext, used once, and then destroyed. An otpad system typically provides components for generation, storage, and synchronization of pad material, as well as interfaces to encode messages and decode replies. Key requirements include truly random or cryptographically secure pad material, secure storage, and a policy ensuring that pad segments are never reused. In practice, otpad tools emphasize offline operation to reduce exposure, with lifecycle controls such as generating pads on a trusted device, transferring them to the communicating party through trusted means, encrypting messages by XOR with the corresponding pad segment, and securely erasing the pad after use.

Because pad material must be at least as long as the message, otpad is logistically challenging for large data volumes, making it most suitable for short messages or high-security communications. Security considerations include hardware integrity, secure erasure, tamper-evidence, and protection against side-channel attacks. Otpad is more of a conceptual model or collection of approaches than a standardized protocol, with various DIY and commercial interpretations. Related topics include one-time pad theory, secure messaging, and key management.