This document summarizes research on providing secure guarantees for network flows. It discusses obfuscation techniques that aim to securely guarantee confidentiality of sensitive data like IP addresses in network traces. The paper identifies threats from incremental release of network flows and proposes applying obfuscation using secure hash algorithms. It formally proves the confidentiality guarantees achieved and evaluates the algorithm experimentally on real network flows. Previous related work on network flow sanitization, fingerprinting, and injection are also reviewed.