Legally Resilient Signatures

Digital signatures are essential to Internet applications and more generally electronic commerce. However, they are subject to various attacks that lend them impractical for some legal applications. In this thesis we consider technologies, which can be used for digital applications in a legally resilient way. We introduce two signature schemes, which combine current biometric research along with digital signature schemes. In order to show the limitation of the human signature, we first introduce a scheme that has an inherent flaw we have deemed the 'fax-copy' attack. By addressing the ability to photocopy a human signature, we strengthen our scheme by allowing a human signature to be encompassed by the digital signature. The second scheme, which we entitle the 'Signet signature scheme', withstands the 'fax-copy' attack and binds a human signature to a digital signature in a legally resilient way.