Blockchain Based Digital Evidence Chain of Custody

With the development of technology, the preservation of digital evidence becomes increasingly important in case investigations. To maintain the authenticity of an evidence, its entire lifecycle has to be recorded. In addition, traditional database technologies are not able to maintain the integrity and authenticity of digital evidence. In order to achieve authentication and integrity, as well as confidentiality, of digital evidence, we propose a protocol for digital evidence chain of custody based on revocable ciphertextpolicy attribute-based encryption, BLS signature, and blockchain technology. In our protocol, attribute-based encryption is used to achieve fine-grained access control and BLS signature is used to verify digital evidence. Besides, we use blockchain technology to ensure the integrity and traceability of digital evidence. Analysis and experimental results show that the proposed protocol, which well balances the privacy and the traceability, guarantees the integrity and validity of evidence.