Certco, Inc.

The United States of America As Represented by the United States

Sandia Corporation

Ernest F Brickell

David William Kravitz

Peter C Freund

Frank W Sudia

Marcel Mordechay Yung

Richard Ankney

Alan Asay

Peter S Gemmell

Patrick J Angeles

Kevin S McCurley

Daniel M Gordon

A multi-step digital signature system and method is provided having a distributed root certifying authority Messages received at the root certifying authority are distributed to root certifying authority members who attach partial signatures to the message using root key fragments. In the system and method provided, the system adapts to system events such as the addition or removal of key fragment holders, the need to modify key fragments, etc., by changing key fragments.

Method of changing key fragments in a multi-step digital signature system

A method of unwrapping wrapped digital data that is unusable while wrapped, includes obtaining an acceptance phrase from a user; deriving a cryptographic key from the acceptance phrase; and unwrapping the package of digital data using the derived cryptographic key. The acceptance phrase is a phrase entered by a user in response to information provided to the user. The information and the acceptance phrase can be in any appropriate language. The digital data includes, alone or in combination, any of: software, a cryptographic key, an identifying certificate, an authorizing certificate, a data element or field of an identifying or authorizing certificate, a data file representing an images, data representing text, numbers, audio, and video.

Electronic cryptographic packing

A multi-step digital signature system and method is provided having a distributed root certifying authority 20. Messages received at the root certifying authority 20 are distributed to root certifying authority members 22-30 who attach partial signatures to the message using root key fragments. In the system and method provided, the system adapts to system events such as the addition or removal of key fragment holders, the need to modify key fragments, etc., by changing key fragments.

Adaptive multi-step digital signature system and method of operation

An off-line electronic cash system having an electronic coin, a bank B, a payee S, and a user U with an account at the bank B as well as a user password z.sub.u,i, has a method for performing an electronic cash transfer. An electronic coin is withdrawn from the bank B by the user U and an electronic record of the electronic coin is stored by the bank B. The coin is paid to the payee S by the user U. The payee S deposits the coin with the bank B. A determination is made that the coin is spent and the record of the coin is deleted by the bank B. A further deposit of the same coin after the record is deleted is determined. Additionally, a determination is made which user U originally withdrew the coin after deleting the record. To perform these operations a key pair is generated by the user, including public and secret signature keys. The public signature key along with a user password z.sub.u,i and a withdrawal amount are sent to the bank B by the user U. In response, the bank B sends a coin to the user U signed by the secret key of the bankindicating the value of the coin and the public key of the user U. The payee S transmits a challenge counter to the user U prior to receiving the coin.

Off-line compatible electronic cash method and system

An improved cryptographic method utilizing exponentiation is provided which has the advantage of reducing the number of multiplications required to determine the legitimacy of a message or user. The basic method comprises the steps of selecting a key from a preapproved group of integer keys g; exponentiating the key by an integer value e, where e represents a digital signature, to generate a value g.sup.e ; transmitting the value g.sup.e to a remote facility by a communications network; receiving the value g.sup.e at the remote facility; and verifying the digital signature as originating from the legitimate user. The exponentiating step comprises the steps of initializing a plurality of memory locations with a plurality of values g.sup.xi ; computi

Growing community of inventors

Albuquerque, NM, United States of America

Ernest F Brickell