Methods for IP Address Encryption and Obfuscation

This document specifies secure, efficient methods for encrypting IP addresses for privacy-preserving storage, logging, and analytics. Unlike truncation, which destroys data irreversibly, these methods are reversible with the encryption key while providing strong privacy guarantees. Four modes are defined: ipcrypt-deterministic (format-preserving, IP- address output), ipcrypt-pfx (prefix-preserving, native address size), ipcrypt-nd and ipcrypt-ndx (non-deterministic with random tweaks). All support high-performance processing at network speeds and produce interoperable results across implementations.