Abstract: A method of verifying a pair of correspondents in electronic transaction, the correspondents each including first and second signature schemes and wherein the first signature scheme is computationally more difficult in signing than verifying and the second signature scheme is computationally more difficult in verifying than signing. The method comprises the step of the first correspondent signing information according to the first signature scheme and transmitting the first signature to the second correspondent, the second correspondent verifying the first signature received from the first correspondent, wherein the verification is performed according to the first signature scheme.

Abstract: An implicit certificate cryptosystem uses an implicit certificate that includes a pair of certificate components. One of the certificate components includes a public key reconstruction data that is the combination of ephemeral public keys of two entities, one of which is a trusted entity and the other of which is associated with the implicit certificate. The public key reconstruction data is then combined with the identity of the other entity and the combination encrypted to form a first certificate component. A second certificate component is generated by using the first certificate component as a message in a signature scheme and generating a signature of the trusted entity on the message. The two certificate components are provided to the other entity to permit the other entity to generate a private key using one of the certificate components. The corresponding public key can be derived from the remaining certificate component.

Abstract: A protocol appropriate for smartcard purchase applications such as those that might be completed between a terminal or ATM and a users personal card is disclosed The protocol provides a signature scheme which allows the card to authenticate the terminal without unnecessary signature verification which is an computationally intense operation for the smart card. The only signature verification required is that of the terminal identification (as signed by the certifying authority, or CA, which is essential to any such protocol). In the preferred embodiment, the protocol provides the card and terminal from fraudulent attacks from impostor devices, either a card or terminal.

Abstract: The present invention relates to data communication systems and protocols utilized in such systems.

Abstract: A portion of the signed message in an ECPVS is kept truly confidential by dividing the message being signed into at least three parts, wherein one portion is visible, another portion is recoverable by any entity and carries the necessary redundancy for verification, and at least one additional portion is kept confidential. The additional portion is kept confidential by encrypting such portion using a key generated from information specific to that verifying entity. In this way, any entity with access to the signer's public key can verify the signature by checking for a specific characteristic, such as a certain amount of redundancy in the one recovered portion, but cannot recover the confidential portion, only the specific entity can do so. Message recovery is also provided in an elliptic curve signature using a modification of the well analyzed ECDSA signing equation instead of, e.g. the Schnorr equation used in traditional PV signature schemes.

Abstract: An implicit certificate cryptosystem uses an implicit certificate that includes a pair of certificate components. One of the certificate components includes a public key reconstruction data that is the combination of ephemeral public keys of two entities, one of which is a trusted entity and the other of which is associated with the implicit certificate. The public key reconstruction data is then combined with the identity of the other entity and the combination encrypted to form a first certificate component. A second certificate component is generated by using the first certificate component as a message in a signature scheme and generating a signature of the trusted entity on the message. The two certificate components are provided to the other entity to permit the other entity to generate a private key using one of the certificate components. The corresponding public key can be derived from the remaining certificate component.

Abstract: A method of verifying a pair of correspondents in electronic transaction, the correspondents each including first and second signature schemes and wherein the first signature scheme is computationally more difficult in signing than verifying and the second signature scheme is computationally more difficult in verifying than signing. The method comprises the step of the first correspondent signing information according to the first signature scheme and transmitting the first signature to the second correspondent, the second correspondent verifying the first signature received from the first correspondent, wherein the verification is performed according to the first signature scheme.

Abstract: The invention relates to a method of generating an implicit certificate and a method of generating a private key from a public key. The method involves a method generating an implicit certificate in three phases. The public key may be an entity's identity or derived from an entity's identify. Only the owner of the public key possesses complete information to generate the corresponding private key. No authority is required to nor able to generate an entity's private key.

Abstract: A method of determining the integrity of a message exchanged between a pair of correspondents. The message is secured by embodying the message in a function of a public key derived from a private key selected by one of the correspondents. The method comprises first obtaining the public key. The public key is then subjected to at least one mathematical test to determine whether the public key satisfies predefined mathematical characteristics. Messages utilizing the public key are accepted if the public key satisfies the predefined mathematical characteristics.

Abstract: A method of representing crytographic values in text form is described. The text representation is formed from words selected from a vocabulary, which may include a collection of pseudowords. The text representations can be further transformed to a paragraph in an apparently grammatically correct form.

Abstract: To verify a pair of correspondents in an electronic transaction, each of the correspondents utilizes respective parts of first and second signature schemes. The first signature scheme is computationally more difficult in signing than verifying and the second signature scheme is computationally more difficult in verifying than signing. The first correspondent signs information according to the first signature scheme, the second correspondent verifies the first signature received from the first correspondent, using the first signature scheme. The second correspondent then signs information according to the second signature scheme and the first correspondent verifies the second signature received from the second correspondent, according to the second signature algorithm. The method thereby allows one of the correspondents in participate with relatively little computing power while maintaining security of the transaction.

Abstract: A method of determining the integrity of a message exchanged between a pair of correspondents. The message is secured by embodying the message in a function of a public key derived from a private key selected by one of the correspondents. The method comprises first obtaining the public key. The public key is then subjected to at least one mathematical test to determine whether the public key satisfies predefined mathematical characteristics. Messages utilizing the public key are accepted if the public key satisfies the predefined mathematical characteristics.

Abstract: A cryptosystem prevents replay attacks within existing authentication protocols, susceptible to such attacks but containing a random component, without requiring modification to said protocols. The entity charged with authentication maintains a list of previously used bit patterns, extracted from a portion of the authentication message connected to the random component. If the bit pattern has been seen before, the message is rejected; if the bit pattern has not been seen before, the bit pattern is added to the stored list and the message is accepted.

Abstract: The present invention relates to data communication systems and protocols utilized in such systems.

Abstract: The present invention relates to data communication systems and protocols utilized in such systems.

Abstract: A passport authentication protocol provides for encryption of sensitive data such as biometric data and transfer of the encryption key from the passport to the authentication authority to permit comparison to a reference value.

Abstract: A public key encryption system exchanges information between a pair of correspondents. The recipient performs computations on the received data to recover the transmitted data or verify the identity of the sender. The data transferred includes supplementary information that relates to intermediate steps in the computations performed by the recipient.

Abstract: A method of generating a public key in a secure digital communication system, having at least one trusted entity CA and subscriber entities A. For each entity A, the trusted entity selects a unique identity distinguishing the entity A. The trusted entity then generates a public key reconstruction public data of the entity A by mathematically combining public values obtained from respective private values of the trusted entity and the entity A. The unique identity and public key reconstruction public data of the entity A serve as A's implicit certificate. The trusted entity combines the implicit certificate information with a mathematical function to derive an entity information ƒ and generates a value kA by binding with ƒ with private values of the trusted entity. The trusted entity transmits the value kA to the entity to permit A to generate a private key from kA, A's private value and A's implicit certificate.

Abstract: Accelerated computation of combinations of group operations in a finite field is provided by arranging for at least one of the operands to have a relatively small bit length. In a elliptic curve group, verification that a value representative of a point R corresponds the sum of two other points uG and vG is obtained by deriving integers w,z of reduced bit length and so that v=w/z. The verification equality R=uG+vQ may then be computed as ?zR+(uz mod n) G+wQ=O with z and w of reduced bit length. This is beneficial in digital signature verification where increased verification can be attained.

Abstract: Accelerated computation of combinations of group operations in a finite field is provided by arranging for at least one of the operands to have a relatively small bit length. In a elliptic curve group, verification that a value representative of a point R corresponds the sum of two other points uG and vG is obtained by deriving integers w,z of reduced bit length and so that v=w/z. The verification equality R=uG+vQ may then be computed as ?zR+(uz mod n) G+wQ=O with z and w of reduced bit length. This is beneficial in digital signature verification where increased verification can be attained.