Gringotts: Securing Data for Digital Evidence

As digital storage and cloud processing become more common in business infrastructure and security systems, maintaining the provable integrity of accumulated institutional data that may be required as legal evidence also increases in complexity. Since data owners may have an interest in a proposed lawsuit, it is essential that any digital evidence be guaranteed against both outside attacks and internal tampering. Since the timescale required for legal disputes is unrelated to computational and mathematical advances, evidential data integrity must be maintained even after the cryptography that originally protected it becomes obsolete. In this paper we propose Gringotts, a system where data is signed on the device that generates it, transmitted from multiple sources to a server using a novel signature scheme, and stored with its signature on a database running Evidence Record Syntax, a protocol for long-term archival systems that maintains the data integrity of the signature, even over the course of changing cryptographic practices. Our proof of concept for a small surveillance camera network had a processing (throughput) overhead of 7.5%, and a storage overhead of 6.2%.