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This research explores the usability aspects of digital signatures, emphasizing their importance alongside cryptography. It considers the need for trusted computing elements and a strong hardware foundation to ensure high assurance. Transaction signatures are identified as a potential game-changer, especially for low-grade transactions. The study also raises important questions regarding the signer and verifier's understanding, recovery from mistakes, strength of signatures, responsibility for revocation, and verification chain.
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Digital Signature Usability Ravi Sandhu George Mason University and TriCipher
Objectives • Emphasize usability not cryptography • But they are interrelated • All the same there are some purely usability issues on which we currently do a terrible job
Think outside the box • Cryptography alone cannot provide assurance of signatures. • It is necessary but not even close to being sufficient • Also need elements of “trusted computing” • founded on a strong hardware base for high assurance • The needs of transaction signatures are very different from those of document or email signatures • Transaction signatures rather than signed email may be the killer application • The biggest productivity gains are in volume of low-grade transactions not so much in automating really high end transactions • There is no such thing as an offline transaction • Transactions are typically verified by computers not by people
Questions (signer oriented) • Can users execute the signature procedure when appropriate? • Do they understand when it's appropriate? • Do they realize the consequences of their actions? • Can they recover if they accidentally make a mistake? • What clues are provided to guide them? • Do all signatures need to be of the same strength? • Who determines what the strength of a signature should be?
Questions (verifier oriented) • Is the verifier a human or a computer • Signed email: human verifier • Signed transaction: computer verifier with possibly human audit and recourse forensics • How do we deal with the revocation problem? • Should the verifier even be responsible for this problem? • Do I have responsibility for ensuring that the signer signed what I intended for the signer to sign? • Is there a notion of a verification chain?
