Towards Automated Transactions Based on the Offline Handwritten Signatures

Automating business transactions over the Internet relies on digital signatures, a replacement of conventional handwritten signatures in paper-based processes. Although they guarantee data integrity and authenticity, digital signatures are not as convenient to users as the manuscript ones. In this paper, a methodology is proposed to produce digital signatures using off-line hand-written signatures. This methodology facilitate the automation of business processes, where users continually employ their handwritten signatures for authentication. Users are isolated from the details related to the generation of digital signatures, yet benefit from enhanced security. First, signature templates from a user are captured and employed to lock his private key in a fuzzy vault. Then, when the user signs a document by hand, his handwritten signature image is employed to unlock his private key. The unlocked key produces a digital signature that is attached to the digitized document. The verification of the digital signature by a recipient implies authenticity of the manuscript signature and integrity of the signed document. Experimental results on the Brazilian off-line signature database (that includes various forgeries) confirms the viability of the proposed approach. Private keys of 1024-bits were unlocked by signature images with Average Error Rate of about 7.8%.