The Futility of Lava Lamps: What Random Means
9 hours ago
- #randomness
- #encryption
- #security
- Cloudflare's use of lava lamps and other physical entropy sources for encryption is primarily marketing and security theater, offering no real security benefit.
- True randomness in encryption is about the observer's lack of knowledge, not intrinsic properties of a source; this is crucial for understanding one-time pads and key security.
- One-time pads require a key as long as the message and are only secure for single use; reusing keys compromises security by revealing information.
- Modern encryption (e.g., authenticated encryption with stream ciphers like ChaCha20 or AES-256) can securely encrypt vast amounts of data with a small key (e.g., 256 bits), contradicting information theory in practice.
- Fast key erasure techniques help mitigate risks if keys leak, by erasing used keys to protect past encrypted data, though future data remains vulnerable if the buffer is compromised.
- Physical true random number generators (TRNGs) are often unnecessary and less secure than cryptographic pseudorandom number generators (CSPRNGs) due to bias issues and added complexity.
- For initial seeding, methods like CPU jitter or hardware RNGs are sufficient and safer than external sources like lava lamps, which introduce unnecessary network and attack surface risks.
- Simplicity in encryption systems is more important than speculative security from physical entropy sources; Cloudflare should rely on server-generated random numbers for better security.