New PKI Protocols Using Tamper Resistant Hardware

Abstract

Keys are indispensable in secure communication, and can only be adequately protected by tamper resistant hardware. Conversely, once you have tamper resistant devices available, you may as well try to make the most of them. In this exposition, we present three novel ideas for the combination of PKI and appropriate use of tamper resistant devices for other purposes than traditional key management. The first isElectronic Negotiable Instruments, such as cash, but there are other important examples, such as Bills of Lading and endorsable checks. The challenge is to prevent double spending without the use of a central registry to keep track of ownership. The second is a new light way digital signature scheme which seems to work well with tamper resistant hardware, but not in software, where it can be broken. We briefly discuss how to make use of this in a transparent PKI solution to be employed by vehicles, which appears to be a hot research topic. Finally we introduce the concept of a digital signature server with central storage of user keys and a central signing facility only, which is operated at the full control of the user using a secure channel for proper authentication. The first and last scenarios have both been deployed in live systems and have been patented, in contrast to the light weight digital signature.