LTANS relevant patents</t> <link rel="stylesheet" type="text/css" href="/ltans.css"> </head> <body> <BODY TEXT="#000000" bgcolor="#FFFFE0" LINK="#009900" VLINK="#006600" ALINK="#FF0000" marginwidth="0" marginheight="0" topmargin="0" leftmargin="0"> </BODY> <blockquote> <h1>Long-Term Archive and Notary Services (ltans) - patents</h1> <p> This documents lists a number of patents which may be relevant for <a href="/">LTANS</a>. The first list is an extract from <a href="rfc3029.txt" target="_extern">RFC 3029</a>. The second list has been compiled by <a href="http://www.cyber.ee" target="_extern">Cybernetica</a> during 20002 as part of the State of the Art Report of the <a href="https://www.openevidence.org" target="_extern">project OpenEvidence</a>. </p> <p> <a href="/">Here is the LTANS home.</a> </p> <pre> # 4,309,569 Method of Providing Digital Signatures (issued) January 5, 1982 (inventor) Ralph C. Merkle (assignee) The Board of Trustees of the Leland Stanford Junior University # 5,001,752 Public/Key Date-Time Notary Facility (issued) March 19, 1991 (inventor) Addison M. Fischer # 5,022,080 Electronic Notary (issued) June 4, 1991 (inventors) Robert T. Durst, Kevin D. Hunter # 5,136,643 Public/Key Date-Time Notary Facility (issued) August 4, 1992 (inventor) Addison M. Fischer (Note: This is a continuation of patent # 5,001,752.) # 5,136,646 Digital Document Time-Stamping with Catenate Certificate (issued) August 4, 1992 (inventors) Stuart A. Haber, Wakefield S. Stornetta Jr. (assignee) Bell Communications Research, Inc., # 5,136,647 Method for Secure Time-Stamping of Digital Documents (issued) August 4, 1992 (inventors) Stuart A. Haber, Wakefield S. Stornetta Jr. (assignee) Bell Communications Research, Inc., # 5,373,561 Method of Extending the Validity of a Cryptographic Certificate (issued) December 13, 1994 (inventors) Stuart A. Haber, Wakefield S. Stornetta Jr. (assignee) Bell Communications Research, Inc., # 5,422,95 Personal Date/Time Notary Device (issued) June 6, 1995 (inventor) Addison M. Fischer # 5,781,629 Digital Document Authentication System (issued) July 14, 1998 (inventor) Stuart A. Haber, Wakefield S. Stornetta Jr. (assignee) Surety Technologies, Inc., </pre> <dl> <dt>[U.S. 5,136,646] Haber, et al. Digital document time-stamping with catenate certificate. August 4, 1992. </dt><dd><p> A system for time-stamping a digital document, for example any alphanumeric, video, audio, or pictorial data, protects the secrecy of the document text and provides a tamper-proof time seal establishing an author's claim to the temporal existence of the document. Initially, the document may be condensed to a single number by means of a one-way hash function, thereby fixing a unique representation of the document text. The document representation is transmitted to an outside agency where the current time is added to form a receipt. The agency then certifies the receipt by adding and hashing the receipt data with the current record catenate certificate which itself is a number obtained as a result of the sequential hashing of each prior receipt with the extant catenate certificate. The certified receipt bearing the time data and the catenate certificate number is then returned to the author as evidence of the document's existence. In later proof of such existence, the certificate is authenticated by repeating the certification steps with the representation of the alleged document, the alleged time data, and the catenate certificate number appearing in the agency's records immediately prior to the certificate number in question. Only if the alleged document is identical to the original document will the original and repeat certificate numbers match. </p></dd><dt>[U.S. 5,136,647] Haber, et al. Method for secure time-stamping of digital documents. August 4, 1992. </dt><dd><p>A system for time-stamping a digital document, including for example text, video, audio, or pictorial data, protects the secrecy of the document text and provides a tamper-proof time seal establishing an author's claim to the temporal existence of the document. Initially, the author reduces the document to a number by means of a one-way hash function, thereby fixing a unique representation of the document text. In one embodiment of the invention the number is then transmitted to an outside agency where the current time is added to form a receipt which is certified by the agency using a public key signature procedure before being returned to the author as evidence of the document's existence. In later proof of such existence, the certificate is authenticated by means of the agency's public key to reveal the receipt which comprises the hash of the alleged document along with the time seal that only the agency could have signed into the certificate. The alleged document is then hashed with the same one-way function and the original and newly-generated hash numbers are compared. A match establishes the identify of the alleged document as the time-stamped original. In order to prevent collusion in the assignment of a time stamp by the agency and thus fortify the credibility of the system, the receipt is linked to other contemporary receipts before certification by the agency, thereby fixing a document's position in the continuum of time. In another embodiment, a plurality of agencies are designated by means of random selection based upon a unique seed that is a function of the hash number of the document to be time-stamped. Thus being denied the ability to choose at will the identity of an agent, the author cannot feasibly arrange for falsification of a time stamp. </p></dd><dt>[U.S. 5,189,700] Blandford. Devices to (1) supply authenticated time and (2) time stamp and authenticate digital documents February 23, 1993. </dt><dd><p>A device to provide authenticated time includes a clock and an encryption circuit enclosed by a seal with a controller for producing an encrypted authentication code of the time read for the clock upon request. An authentication device number can be combined with the time data before encryption. Additionally, the device can receive text or other data (either complete text or a hash of a text document) and combine the text data with the time data before encryption so that the encrypted authentication code is formed from the combined data. Optionally the device can produce, time stamp and authenticate the hash of data. Other material such as user and/or device sequence number and/or a random number can be included in the data used in forming the encrypted authentication code. </p></dd><dt>[U.S. 5,214,702] Fischer. Public key/signature cryptosystem with enhanced digital signature certification. May 25, 1993. </dt><dd><p>A public key cryptographic system is disclosed with enhanced digital signature certification which authenticates the identity of the public key holder. A hierarchy of nested certifications and signatures are employed which indicate the authority and responsibility levels of the individual whose signature is being certified. The certifier in constructing a certificate generates a special message that includes fields identifying the public key which is being certified, and the name of the certifiee. The certificate is constructed by the certifier to define the authority which is being granted and which may relate to a wide range of authorizations, delegation responsibilities or restrictions given to, or placed on the certifiee. Methodology is also disclosed by which multiple objects such as, for example, a cover letter, an associated enclosed letter, an associated graphics file, etc., are signed together. Methodology is also disclosed for digitally signing documents in which a digital signature is generated for both computer verification and for reverification if a document needs to be reconfirmed by reentering from a paper rendition. </p></dd><dt>[U.S. RE34,954] Haber, et al. Method for secure time-stamping of digital documents. May 30, 1995. </dt><dd><p>A system for time-stamping a digital document, including for example text, video, audio, or pictorial data, protects the secrecy of the document text and provides a tamper-proof time seal establishing an author's claim to the temporal existence of the document. Initially, the author reduces the document to a number by means of a one-way hash function, thereby fitting a unique representation of the document text. In one embodiment of the invention the number is then transmitted to an outside agency where the current time is added to form a receipt which is certified by the agency using a public key signature procedure before being returned to the author as evidence of the document's existence. In later proof of such existence, the certificate is authenticated by means of the agency's public key to reveal the receipt which comprises the hash of the alleged document along with the time seal that only the agency could have signed into the certificate. The alleged document is then hashed with the same one-way function and the original and newly-generated hash numbers are compared. A match establishes the identify of the alleged document as the time-stamped original. In order to prevent collusion in the assignment of a time stamp by the agency and thus fortify the credibility of the system, the receipt is linked to other contemporary receipts before certification by the agency, thereby fixing a document's position in the continuum of time. In another embodiment, a plurality of agencies are designated by means of random selection based upon a unique seed that is a function of the hash number of the document to be time-stamped. Thus being denied the ability to choose at will the identity of an agent, the author cannot feasibly arrange for falsification of a time stamp. </p></dd><dt>[U.S. 5,373,561] Haber, et al. Method of extending the validity of a cryptographic certificate. December 13, 1994. </dt><dd><p>A cryptographic certificate attesting to the authenticity of original document elements, such as time of creation, content, or source, will lose its value when the cryptographic function underlying the certifying scheme is compromised. The present invention provides a means for extending the reliability of such a certificate by subjecting, prior to any such compromise, a combination of the original certificate and the document digital representation from which that certificate was derived to a scheme based on a different and ostensibly less vulnerable function. The new certificate resulting from this procedure extends the validity of the original authenticity by implacably incorporating the original certificate at a time when that certificate could only have been derived by legitimate means. </p></dd><dt>[U.S. 5,347,579] Blandford. Personal computer diary. September 13, 1994. </dt><dd><p>A computer diary archives a diary entry by creating, time stamping, authenticating and permanently storing a reference data block along with each diary entry. An archived diary entry can only be modified by placing original text within compartment codes, such as cross-out or tear-out codes, and by placing inserted text within insertion codes so that the original diary entry can be recreated from the modified diary entry. The reference data block, which can be the original diary entry, a canonical version of the original diary entry, or a one way fixed length encryption (hash) of the original diary entry, cannot be modified and is used to authenticate the original diary entry. The diary program also monitors text entry for aliases and relative date phrases, and upon detection, prompts the user for entry or enters a specific identifier for each detected alias in an alias compartment or an absolute date for each relative date phrase in an implied date compartment in the diary entry. </p></dd><dt>[U.S. 5,781,629] Haber, et al. Digital document authentication system. July 14, 1998. </dt><dd><p>A process for time-stamping a digital document is provided. The process provides a certificate which not only allows for the authentication of a document at a later time but which includes a name or nickname which allows for the unique identification of the document at a later time. The name or nickname provided in accordance with the present invention is not only simple and concise but allows for the self-authentication of the document which it refers to. The name can be used when two independent parties desire to refer to the same unique document in a quick and simple way. </p></dd><dt>[U.S. 6,393,566] Levine. Time-stamp service for the national information network. May 21, 2002. </dt><dd><p>A system and method for time-stamping and signing a digital document by an authenticating party and returning the signed stamped document to the originator or his designated recipient. Messages may be received by a first "public" machine over a network, by fax, or through input mediums such as diskettes. The clock of the first machine is synchronized with Universal Coordinated Time (UTC) and can be checked for accuracy by anyone on the network. A second "private" machine, not connected to any network, receives the time-stamped message, applies a hashing procedure and provides a signature using a private key. The signed hashed time-stamped message is then returned. A verify procedure is made widely available to check the genuiness of a document by rehashing the document and applying a public key. The result should match the signed time-stamped message returned by the authenticating party. </p></dd><dt>[U.S. 6,381,696] Doyle. Method and system for transient key digital time stamps. April 30, 2002. </dt><dd><p>Irrefutable public key digital signature time-stamps are created and used based upon, for example, the concept of transient time interval-related secret cryptographic keys, which are used to digitally sign submitted data during specific time intervals, and then are permanently destroyed. The public-key correlate for each time interval is saved for future authentication of the content of time-stamped data and time of creation of time-stamped data. The validity of the public keys is ensured through the certification of each time interval's public key using the previous time interval's secret key, immediately before that secret key is destroyed. </p></dd> </dl> <h4>Maintenance of this site: Peter Sylvester <<a href="mailto:peter.sylvester@edelweb.fr?subject=ltans-web">peter.sylvester@edelweb.fr</a>></h4> </blockquote> </body> </HTML>