Frank P Leighton

US Patent:

56640188, Sep 2, 1997

Filed:

Mar 12, 1996

Appl. No.:

8/615534

Inventors:

Frank Thomson Leighton - Newtonville MA

International Classification:

G09C 500
H04L 900

US Classification:

380 54

Abstract:

A watermarking procedure wherein each of a set of copies of the work has a slightly-modified form of a "baseline" watermark that is placed within a critical region of the data. The slight variations in the watermarks, however, are not perceptually visible and do not interfere with the work. If multiple persons collude to attempt to create an "illicit" copy of the work (i. e. , a copy without a watermark), however, at least one of the modified watermarks is present in the copy, thereby identifying both the illicit copy and the copier.

US Patent:

55215912, May 28, 1996

Filed:

Mar 25, 1994

Appl. No.:

8/218318

Inventors:

Sanjeev Arora - Berkeley CA
Thomas F. Knight - Belmont MA
Frank T. Leighton - Newton Center MA
Bruce M. Maggs - Princeton NJ
Eliezer Upfal - Palo Alto CA

Assignee:

Massachusetts Institute of Technology - Cambridge MA

International Classification:

H01H 6700

US Classification:

340826

Abstract:

A class of switching networks is comprised of expansive logical clusters and/or dispersive logical clusters. These clusters are of low degree. The class of networks include multibutterfly networks as well as multi-Benes networks. These networks provide for fault tolerance and routing and for efficient routing. Moreover, routing is provided in a non-blocking fashion.

US Patent:

53513029, Sep 27, 1994

Filed:

May 26, 1993

Appl. No.:

8/067493

Inventors:

Frank T. Leighton - Newtonville MA
Silvio Micali - Brookline MA

International Classification:

H04L 930
H04L 932

US Classification:

380 30

Abstract:

The method and system of the present invention utilizes public-key cryptography to create "secure" titles for personal and real property such as vehicles and the like. The title preferably comprises a card in which is stored a digital signature of one or more identifiers such as a vehicle identification number, the vehicle license plate and the owner's name. To effect a transfer of the property, the digital signature on the title must first be shown to have been generated from the one or more identifiers.

US Patent:

48797472, Nov 7, 1989

Filed:

Mar 21, 1988

Appl. No.:

7/170734

Inventors:

Frank T. Leighton - Newton Center MA
Silvio Micali - Cambridge MA

International Classification:

H04K 100

US Classification:

380 23

Abstract:

The method and system of the invention utilizes a private key of a public-key cryptosystem key pair to encrypt a non-secret password into a digital signature. The password and the digital signature are then encoded and stored on a magnetic stripe or other memory device of the card. To effect a transaction, the digital signature on a received card must be shown to have been generated from the password on the received card. The password preferably includes a digitized photograph of the authorized cardholder which is capable of being displayed at the transaction terminal. This enables the operator of the terminal to verify the identity of the cardholder by visual inspection.

US Patent:

56470002, Jul 8, 1997

Filed:

Sep 3, 1996

Appl. No.:

8/706975

Inventors:

Frank Thomsen Leighton - Newtonville MA

International Classification:

H04L 930

US Classification:

380 30

Abstract:

A method of generating cryptographic keys to implement a Failsafe Key Escrow system. A prime modulus Q and a generator G for Z. sub. Q are publicly known. The public key P. sub. X that is escrowed for user X is G. sup. SX mod Q, where Sx is the secret key for user X. The user picks a random secret value A from [0, Q-2] and announces the value of G. sup. A mod Q to a set of trustees or a central authority. Next the user "shares" A with the trustees using a verifiable secret sharing scheme. The trustees and/or the central authority selects a random value B from the interval [0, Q-2] and they set the user's public key to be P. sub. X =(G. sup. A)G. sup. B mod Q. The value of B is returned to the user and is escrowed with the public key for X. The value of B is not released to the public. The user's then sets his secret key to be S. sub.

US Patent:

55197787, May 21, 1996

Filed:

Sep 26, 1994

Appl. No.:

8/312567

Inventors:

Frank T. Leighton - Newtonville MA
Silvio Micali - Brookline MA

International Classification:

H04L 908
H04L 930

US Classification:

380 30

Abstract:

The present invention describes a method for enabling users of a cryptosystem to agree on secret keys. In one embodiment, a trusted agent chooses at least one individual key for each user, with at least a portion of such individual key being secret. At least some of the individual keys are then stored in physically secure devices, and the pair of users i and j use their individual keys to compute a common secret key. In another embodiment, each trustee of a group of trustees choose at least one individual key for each user, with at least some portion of such individual key being secret. The keys chosen by a sufficiently small number of such trustees, however, are insufficient for computing the common secret key of the users. Other hardware and software key exchange protocols based on these two techniques are also disclosed.

US Patent:

49950819, Feb 19, 1991

Filed:

Nov 6, 1989

Appl. No.:

7/432130

Inventors:

Frank T. Leighton - Newton Center MA
Silvio Micali - Cambridge MA

International Classification:

H04K 100

US Classification:

380 23

Abstract:

The method and system for the invention utilizes any of a number of "proofs of legitimacy" to generate and verify a personal identification card. A card is generated by computing a digital signature of a non-secret password. The password and the digital signature are then encoded and stored on a magnetic stripe or other memory device of the card. To effect a transaction, the digital signature on a received card must be shown to have been generated from the password on the received card. The password preferably includes a digitized photograph of the authorized cardholder which is capable of being displayed at the transaction terminal. This enables the operator of the terminal to verify the identity of the cardholder by visual inspection.

US Patent:

54328527, Jul 11, 1995

Filed:

Sep 29, 1993

Appl. No.:

8/128514

Inventors:

Frank T. Leighton - Newtonville MA
Silvio Micali - Brookline MA

International Classification:

H04L 900
H04L 930

US Classification:

380 30

Abstract:

The present invention describes new digital signature schemes that are provably secure against any adaptive chosen-message attack. The scheme, which is based on selection of a hash function from a space of such functions, has a very short public key, fast signing, a reasonable signature length and high security. Several algorithmic techniques are provided for enhancing the efficiency of the signature scheme in terms of time and memory.