Bryant Nielson | November 8, 2023
Robust key generation starts with high-quality randomness. Private keys should have ample entropy to make guessing infeasible. Pseudo-random number generators on standard computers are inappropriate since they utilize deterministic algorithms. Hardware security modules (HSMs) provide high-assurance key generation through true randomness leveraging physical sources of entropy.
Once generated, private keys must remain exclusively in the possession of owners. For organizations, this requires secure key storage and distribution mechanisms. Common methods include encrypted USB drives, smart cards/hardware wallets, and HSM-backed software wallets. Printed QR codes or paperwork are risky. Strict access controls are imperative, especially for centralized storage.
Multi-signature (multisig) schemes provide added protection by requiring multiple keys to authorize transactions. This limits exposure if any one key is compromised. Multisig configurations should balance security and practicality. Requiring all keys for routine transactions creates availability risks.
For maximum resilience, keys can be generated and stored in segmented form through protocols like Shamir’s Secret Sharing. Here, a private key is divided into multiple fragments with some fragments sufficient to reconstruct the key. Segmenting keys across distinct storage locations prevents single points of failure.
Centralized key management on Creator machines creates inherent risks. Decentralized approaches where users generate and store keys locally provide greater assurance. Firms like Blockchain Commons promote decentralized key architectures and offer open-source implementations. However, usability challenges remain with decentralized models.
Throughout their lifecycle, keys must be properly provisioned, rotated, and revoked as appropriate. Crypto-agility, algorithms, and key lengths should evolve with technological advancements. Legacy keys may weaken over time and require replacement. Sound key governance is essential.
For blockchain developers, best practices include using vetted libraries instead of implementing cryptographic primitives from scratch. Common pitfalls like seed reuse, faulty random number generators, or not salting hashes can introduce vulnerabilities that attackers exploit. Thorough testing and audits by experts can uncover subtle design flaws.
Ongoing innovation around blockchain key management includes trusted execution environments (TEEs) leveraging secure enclaves in hardware chips. TEEs allow isolated generation and use of keys within tamper-resistant hardware boundaries. However, some TEE vulnerabilities have surfaced. Conservatively deploying TEEs after rigorous security analysis is advised.
In summary, blockchain keys act as the gateway to users’ assets and data. Robust key management provides the lock and key. With decentralized systems proliferating, organizations must engineer key safeguards spanning the entire lifecycle. Diligent design, generation, storage, governance and upgrading of keys will define the security of blockchain and crypto-economic systems for generations to come.