Patent ID: 8271791

Claim:
A method comprising: digitally signing an electronic document for long term security purposes and user involvement, digitally signing comprising steps of: at a signature server: marking the electronic document with a digital mark forming a marked electronic document, wherein said digital mark is dependent upon content of said electronic document; generating a first digital signature using the digital mark, using a plurality of different signature schemes in parallel; signing the marked electronic document with a first digital signature forming a signed electronic document; providing the marked electronic document and the first digital signature to a client computer to be verified; signing a second digital signature employing a computer device, signed by a user of said computer device using a cryptographic token, said second digital signature being dependent on the content of the electronic document and the first digital signature that is less computationally intensive in its generation than the first digital signature; wherein the second digital signature is based on a shorter cryptographic key than the first digital signature; receiving the marked electronic document, the first digital signature, and the second digital signature from the client computer; adding a third digital signature to generate a verified electronic document; and storing the verified electronic document in a repository.