Resilia: a Safe and Secure Distributed Backup System for Small and Medium Enterprises

Most small and medium-sized enterprises (SME) operate from a single address, which means that backups are normally kept at the same physical location as the company’s computers. This means that fire, flooding or other disasters are likely to destroy both computers and the backups that were meant to ensure the continued operation of the company. The price per Giga-byte of hard disk storage is falling and at the same time the bandwidth of the connection from small companies to the Internet is increasing, so it appears logical for small companies to achieve improved availability of their backups by storing backups on the hard disk of one or more remote computers. However, storing business-critical information or customer data on a foreign computer requires a mechanism that preserves the secrecy and ensures the integrity of the stored data. This paper presents Resilia, which is a safe and secure backup system that allows a company to distribute its backup among a number of remote servers, thereby ensuring availability, without compromising the confidentiality and the integrity of the backup. The confidentiality of data in Resilia is ensured with an encryption technique known as threshold cryptography, which means that a backup can be restored even if all cryptographic keys are lost in a disaster. We describe a working prototype of Resilia and report initial performance numbers for the developed prototype.