Attribute-based encryption for blockchain-based traceability system

Abstract

Traceability, being the ability to access information of an item throughout its lifecycle, plays an important part in nowadays' supply chain, facilitating prompt response in case of incidents. In recent years, blockchain-based traceability systems have been proposed to address the multi-party data exchange issue with emerging technology while achieving external traceability.

In this thesis, it is argued that attribute-based encryption can be applied to blockchain-based traceability system such that trade secrets are well-protected in such blockchain system. Particularly three statically secure decentralized ciphertext-policy attribute-based encryption schemes are proposed. Delegation is one of the features supported by the proposed schemes which opens to an alternative way of requesting decryption keys while maintaining collusion resistance in the cryptosystems. Policy-hiding is also supported such that sensitive information lying in the access policies does not leak to unauthorized users. The proposed schemes also support instantiation of attribute public keys in large universe construction such that attribute authorities do not need to disclose descriptive attribute names for encryption and thus preserve secrecy if the names are sensitive. The performance of the proposed schemes is also evaluated and compared to other schemes.

Moreover, we propose and implement an architecture of blockchain-based traceability system which aims to prevent trade secret leakage. The proposed system integrates with the proposed ABE scheme as well as Quorum, InterPlanetary File System and hierarchical deterministic key generation. These components and cryptographic algorithms help the implemented system achieve data confidentiality and identity anonymity, which are important to safeguard the trade secret. Traversal of traceability records is also supported by the implemented system such that product tracking and traceback along the supply chain can be performed.