PUBLIC KEY CRYPTOGRAPHY AND A FRAMEWORK THEREFOR

摘要

A method of performing a public/private key operation is disclosed comprising: generating a private and public key pair, the public key having a lifetime; selecting a plurality of intervals within the lifetime and a plurality of respective identifiers, each interval being associated with a said identifier; and having a trusted third party generate a public key certificate which includes the public key and a final identifier, the identifiers being selected so that it is relatively difficult to derive an identifier associated with a said interval from the final identifier but relatively easy to derive the final identifier from an identifier associated with a said interval, a said identifier being provided by a user with any matter signed or otherwise operated upon using the private key in the associated interval to confirm the validity of the certificate in that interval. A forward-secure digital signature scheme in which transactions for validity periods both before and after the current period remain secure even if the private key for the current period is compromised is also disclosed.