Certicom Corporation

Minghua Qu

Scott Alexander Vanstone

Alfred John Menezes

Donald B Johnson

Rene Struik

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.

Strengthened public key protocol

A method for creating and authenticating a digital signature is provided, including selecting a first session parameter k and generating a first short term public key derived from the session parameter k, computing a first signature component r derived from a first mathematical function using the short term public key, selecting a second session parameter t and computing a second signature component s derived from a second mathematical function using the second session parameter t and without using an inverse operation, computing a third signature component using the first and second session parameters and sending the signature components (s, r, c) as a masked digital signature to a receiver computer system. In the receiver computer system, a recovered second signature component s' is computed by combining a third signature component with the second signature component to derive signature components (s&#x2032;, r) as an unmasked digital signature.

Masked digital signatures

A method of generating a public key in a secure digital communication system, having at least one trusted entity CA and subscriber entities A. The trusted entity selects a unique identity distinguishing each 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 f and generates a value kby binding f with private values of the trusted entity. The trusted entity transmits the value kto the entity to permit A to generate a private key from k, A's private value and A's implicit certificate.

Implicit certificate scheme

A method of generating a public key in a secure digital communication system, having at least one trusted entity CA and subscriber entities A. The trusted entity selects a unique identity distinguishing each 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 &#x192; and generates a value kby binding &#x192; with private values of the trusted entity. The trusted entity transmits the value kto the entity to permit A to generate a private key from k, A's private value and A's implicit certificate.

The present invention relates to digital signature operations using public key schemes in a secure communications system and in particular for use with processors having limited computing power such as 'smart cards'. This invention describes a method for creating and authenticating a digital signature comprising the steps of selecting a first session parameter k and generating a first short term public key derived from the session parameter k, computing a first signature component r derived from a first mathematical function using the short term public key, selecting a second session parameter t and computing a second signature component s derived from a second mathematical function using the second session parameter t and without using an inverse operation, computing a third signature component using the first and second session parameters and sending the signature components (s, r, c) as a masked digital signature to a receiver computer system. In the receiver computer system computing a recovered second signature component s' by combining a third signature component with the second signature component to derive signature components (s&#x2032;, r) as an unmasked digital signature. Verifying these signature components as in a usual EIGamal or ECDSA type signature verification.

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 &#x192; and generates a value kby binding with &#x192; with private values of the trusted entity. The trusted entity transmits the value kto the entity to permit A to generate a private key from k, A's private value and A's implicit certificate. The entity A's public key information may be reconstructed from public information, and A's implicit certificate.

A key establishment protocol between a pair of correspondents includes the generation by each correspondent of respective signatures. The signatures are derived from information that is private to the correspondent and information that is public. After exchange of signatures, the integrity of exchange messages can be verified by extracting the public information contained in the signature and comparing it with information used to generate the signature. A common session key may then be generated from the public and private information of respective ones of the correspondents.

Key agreement and transport protocol with implicit signatures

The present invention relates to digital signature operations using public key schemes in a secure communications system and in particular for use with processors having limited computing power such as 'smart cards'. This invention describes a method for creating and authenticating a digital signature comprising the steps of selecting a first session parameter k and generating a first short term public key derived from the session parameter k, computing a first signature component r derived from a first mathematical function using the short term public key, selecting a second session parameter t and computing a second signature component s derived from a second mathematical function using the second session parameter t and without using an inverse operation, computing a third signature component using the first and second session parameters and sending the signature components (s, r, c) as a masked digital signature to a receiver computer system. In the receiver computer system computing a recovered second signature component s' by combining a third signature component with the second signature component to derive signature components (s&#x2032;, r) as an unmasked digital signature. Verifying these signature components as in a usual ElGamal or ECDSA type signature verification.

A method of a trusted entity CA facilitating generation of a public key by an entity A in an electronic data communication system using implicit certificates. The trusted entity CA selects a unique identity distinguishing the entity A. The trusted entity CA then generates a public key reconstruction public data of the entity A by mathematically combining a private value of said trusted entity CA and information made public by said trusted entity CA. The unique identity and public key reconstruction public data of file entity A serve as A's implicit certificate. The trusted entity CA generates a private key for said entity A using said implicit certificate and said private value of said trusted entity CA. The trusted entity CA then transmits the unique identity, public key reconstruction public data, and private key to the entity A to permit A to generate a public key from the public key reconstruction public data and the private key.

A key establishment protocol includes the generation of a value of cryptographic function, typically a hash, of a session key and public information. This value is transferred between correspondents together with the information necessary to generate the session key. Provided the session key has not been compromised, the value of the cryptographic function will be the same at each of the correspondents. The value of the cryptographic function cannot be compromised or modified without access to the session key.

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Mississauga, Canada

Minghua Qu