Threats and risks against supply chains are increasing and a framework to add the trustworthiness of supply chain has been considered. In this framework, organisations in the supply chain validate the conformance to the pre-defined requirements. The results of validations are linked each other to achieve the trustworthiness of the entire supply chain. In this paper, we further consider this framework for data supply chains. First, we implement the framework and evaluate the performance. The evaluation shows 500 digital evidences (logs) can be checked in 0.28 second. We also propose five methods to improve the performance as well as five new functionalities to improve usability. With these functionalities, the framework also supports maintaining the certificate chain.

Public-key encryption with keyword search (PEKS) is a cryptographic primitive that allows us to search encrypted data for those of including particular keywords without decrypting them. PEKS is expected to be used for enhancing security of cloud storages. It is known that PEKS can be constructed from anonymous identity-based encryption (IBE), anonymous attribute-based encryption (ABE) and so on. It is believed that it is difficult to construct PEKS schemes that can specify a flexible search condition such as logical disjunctions and logical conjunctions from weaker cryptographic tools than ABE. However, this intuition has not been rigorously justified. In this paper, we formally prove it by constructing key-policy ABE from PEKS for monotone boolean formulas.