Hewlett-packard Development Company, L.P.

Caroline Kudla

Liqun Chen

David Trastour

Christopher William Preist

Javier Esplugas Cuadrado

A method of determining the compatibility of respective information associated with at least two parties is described. The method comprises: a first and second party each expressing their respective information in an agreed format; processing the information according to a two-phase double-encryption process, in which the first party encrypts their information under a personalized first-phase procedure and sends the results to the second party and the second party encrypts their information under a personalized first-phase procedure and sends the results to the first party, the second party encrypting the encrypted information received from the first party under a personalized second-phase procedure to produce a double-encrypted result and the first party encrypting the encrypted information received from the second party under a personalized second-phase procedure to produce a double-encrypted result, the first- and second-phase procedures being chosen such that a given element of information will always yield the same unique double-encrypted result regardless of which party it originates from; and comparing each party's double-encrypted information to determine the compatibility of the information of each party.

System and method for constraint resolution

A digital signature method and apparatus is provided in which a first party with a first public/private key pair forms an ambiguous signature on subject data using at least the private key of the first key pair, a keystone initially only known to the first party, and the public key of at least one other public/private key-pair. This signature is ambiguous in that a signature-checking party can only verify that the signature is in the set comprising a signature created by the first party and a respective signature created by the possessor of the private key of the or each of the key pairs the public key of which was used in creating the signature. Revelation of the keystone renders the signature unambiguous. Such an ambiguous signature can be used to implement a fair exchange of signatures between any number of parties, with the exchanged signatures being ambiguous signatures until revelation of the initial signer's keystone.

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Bristol, United Kingdom

Caroline Kudla