Implicit certificate

Abstract: This document specifies a protocol useful in determining the current status of a digital certificate without requiring CRLs. Additional mechanisms addressing PKIX operational requirements are specified in separate documents.

Abstract: A public key cryptographic system is disclosed with enhanced digital signature certification which authenticates the identity of the public key holder. A hierarchy of nested certifications and signatures are employed which indicate the authority and responsibility levels of the individual whose signature is being certified. The certifier in constructing a certificate generates a special message that includes fields identifying the public key which is being certified, and the name of the certifiee. The certificate is constructed by the certifier to define the authority which is being granted and which may relate to a wide range of authorizations, delegation responsibilities or restrictions given to, or placed on the certifiee. Methodology is also disclosed by which multiple objects such as, for example, a cover letter, an associated enclosed letter, an associated graphics file, etc., are signed together. Methodology is also disclosed for digitally signing documents in which a digital signature is generated for both computer verification and for reverification if a document needs to be reconfirmed by reentering from a paper rendition.

Abstract: A cryptographic system with key escrow feature that uses a method for verifiably splitting user's private encryption keys into components and for sending those components to trusted agents chosen by the particular users is provided. The system uses public key certificate management, enforced by a chip device that also self-certifies. The methods for key escrow and receiving an escrow certificate are applied to register a trusted device with a trusted third party and to receive authorization from that party enabling the device to communicate with other trusted devices. The methods for key escrow also provide assurance that a trusted device will engage in electronic transactions in accordance with predetermined rules.

Abstract: We introduce the notion, and give two examples, of self-certified public keys, i.e. public keys which need not be accompanied with a separate certificate to be authenticated by other users. The trick is that the public key is computed by both the authority and the user, so that the certificate is "embedded" in the public key itself, and therefore does not take the form of a separate value. Self-certified public keys contribute to reduce the amount of storage and computations in public key schemes, while secret keys are still chosen by the user himself and remain unknown to the authority. This makes the difference with identity-based schemes, in which there are no more certificates at all, but at the cost that secret keys are computed (and therefore known to) the authority.