# US 8,751,812 B2 · Electronic signature authentication > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,751,812 B2 - Document ID: US8751812B2 - Status: Granted - Kind: B2 - Application number: 13/549,505 - Filed: 2012-07-15 - Published: 2013-01-31 - Granted: 2014-06-10 - Earliest claimed: 2011-07-15 - Assignees: Dictao - Applicants: Raphaël Daouphars; Jean-Marc Desperrier; Laurent Fournié - Inventors: Raphaël Daouphars; Jean-Marc Desperrier; Laurent Fournié - Web page: https://patentgrep.com/patent/US8751812B2 ## CPC - H04L 9/3247: {involving digital signatures} - G06F 21/645: {using a third party} - G06Q 10/101: Collaborative creation, e.g. joint development of products or services - G06Q 50/18: Legal services - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - G06Q: INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR ## Abstract Method of authenticating a signature on a work document in which a remote server generates a digital work fingerprint and a representation file of the work document. The representation file and the digital work fingerprint are transmitted to a client station from the remote server via a wide area communication network, and at least one digital representation fingerprint of the representation file is generated. A file to be signed is generated containing at least the digital work and representation fingerprints. The client station generates only one client signature from the file to be signed, and a client signature file is generated containing at least the file to be signed and the client signature. ## Claims ### Claim 1 Method of authenticating a signature on a work document, comprising: a remote server generating a digital work fingerprint of the work document; the remote server generating a representation file of the work document; transmitting the representation file and the digital work fingerprint to a client station from the remote server via a wide area communication network; generating at least one digital representation fingerprint of the representation file; generating a file to be signed containing at least the digital work fingerprint and the digital representation fingerprint; the client station generating only one client signature from the file to be signed; and generating a client signature file containing at least the file to be signed and the client signature. ### Claim 2 (depends on 1) Method according to claim 1, further comprising: presenting at least part of the representation file at the client station; and initiating the signature generation step by a user. ### Claim 3 (depends on 1) Method according to claim 1, wherein the digital fingerprint of the representation file and the file to be signed are generated by the client station. ### Claim 4 (depends on 1) Method according to claim 1, wherein the digital fingerprint of the representation file and the file to be signed are generated by the remote server and/or a third-party server and transmitted to the client station via the wide area communication network. ### Claim 5 (depends on 4) Method according to claim 4, further comprising: the client station generating a digital control representation fingerprint of the representation file; and the client station comparing the representation fingerprint contained in the file to be signed with the control presentation fingerprint in order to authorize, in case of a match, generating the client signature. ### Claim 6 (depends on 1) Method according to claim 1, wherein the signature file is generated by the remote server or a third-party server. ### Claim 7 (depends on 1) Method according to claim 1, wherein the representation file is a file intended for a presentation via a man-machine interface in a form directly intelligible to the user. ### Claim 8 (depends on 1) Method according to claim 1, wherein the representation file is adapted for a continuous presentation or a continuous reading and contains at least one sequence liable to be covered by a presentation, the content of each at least one sequence of the representation file being: independent of the content of subsequent sequences, if any; and independent of the execution environment of the presentation step. ### Claim 9 (depends on 1) Method according to claim 1, wherein generating the representation file comprises implementing an identified program transforming the work document into the representation file. ### Claim 10 (depends on 9) Method according to claim 9, wherein the representation file is associated with an identifier of the transformation program. ### Claim 11 (depends on 9) Method according to claim 9, wherein the file to be signed includes the identifier of the transformation program. ### Claim 12 (depends on 1) Method according to claim 1, wherein the file to be signed contains a server signature generated by the remote server and applied to at least one of: the work fingerprint; the representation fingerprint; and the identifier of the transformation program. ### Claim 13 (depends on 12) Method according to claim 12, further comprising checking the server signature. ### Claim 14 (depends on 1) Method according to claim 1, further comprising checking the authenticity of the work document from the signature file associated with the work document, the checking step comprising: extracting the work fingerprint from the signature file; calculating a new digital fingerprint from the work document; and comparing the work fingerprint and the new digital fingerprint to determine if the work document is authentic. ### Claim 15 (depends on 1) Method according to claim 1, further comprising checking the authenticity of the representation file of the work document from the signature file associated with the work document, the checking step comprising: extracting the representation fingerprint from the signature file; generating a new representation file from the work document; calculating a new digital fingerprint from the new representation file; and comparing the representation fingerprint and the new digital fingerprint to determine if the representation file of the work document is authentic. ### Claim 16 (depends on 8) Method according to claim 8, wherein the content of each at least one sequence of the representation file is dependent on the content of the sequence immediately preceding it.