BAAR: A framework for blockchain-based anonymous and revocable user authentication scheme

Area of Science:

• Cryptography and Information Security
• Distributed Systems and Blockchain Technology

Background:

• Existing blockchain authentication methods struggle to balance privacy, accountability, and efficient revocation.
• Pairing-based cryptography in current anonymous schemes leads to high computational overhead, limiting scalability on platforms like Ethereum.

Purpose of the Study:

• To present BAAR, a Blockchain-based Anonymous and Revocable authentication framework.
• To enable anonymous and unlinkable authentication with selective attribute disclosure and auditable revocation.
• To reduce on-chain computation and gas costs for blockchain authentication.

Main Methods:

• Utilizes discrete logarithm setting over the secp256k1 elliptic curve.
• Integrates Pedersen vector commitments, Schnorr-based zero-knowledge proofs, and a Merkle-tree-based dynamic accumulator.
• Performs authentication and verification off-chain, maintaining only a compact revocation state on-chain.

Main Results:

• Formal security analysis confirms unforgeability, unlinkability, attribute privacy, and revocation soundness.
• Prototype implementation demonstrates low gas consumption and logarithmic-time revocation.
• Achieves scalable performance with respect to the number of users and attributes.

Conclusions:

• BAAR offers a practical solution for blockchain authentication, balancing strong privacy with deployability.
• The framework is suitable for real-world blockchain-based identity and access-control systems.
• Significantly reduces on-chain computational burden and gas fees.