1. A method for implementing a digital signature scheme, comprising: obtaining a digital document; embedding, with a processor, multiple data fields in the digital document and filling the multiple data fields with filler data to arrive at a final digital document having a final document size; applying an encrypting hash scheme to the final digital document to obtain a first hash value; encrypting the first hash value using a first encryption key to obtain a first digital signature; and substituting a first identifier associated with the first encryption key and the first digital signature for the filler data in a first data field and a second data field of the multiple data fields in the final digital document to obtain a first signed final digital document.