Thesis (M.Sc.)--Chulalongkorn University, 2015

Most certificate or document issuing processes are in a form of printing document to a paper. Some might improve the trustworthiness of their paper via using secure paper or secure printing method such as watermark, hologram etc. The interesting problem is that this security mechanism is not enough because nowadays printer with secure printing module can be obtained easier than before, which means reproducing counterfeit document can be done uncomplicatedly. To solve this problem, a security framework using image hashing function to capture document fingerprint and perform a digital signature based on PKI infrastructures is proposed to guarantee this fingerprint integrity. This framework consists of three important components. The first component is image hashing function for capturing perceptual appearance of printing document and it is then used to verify integrity of their document. The second component is digital signature based on PKI infrastructure for protecting image hash value from modification, authenticating document signer and guaranteeing content commitment from the document signer. The last important component of this proposed framework is 2D barcode for embedding result from the digital signature process that belongs to their printing document.