  Electronic documents are signed using private keys and verified using the
corresponding digital certificates through the well-known public key
infrastructure model. Private keys must be kept in a safe container so they can
be reused. This makes private key management a critical component of public key
infrastructures with no failproof answer. Therefore, existing solutions must
employ cumbersome and often expensive revocation methods to handle private key
compromises. We propose a new cryptographic key management model built with
long-term, irrevocable digital certificates, each bound to a single document.
Our model issues a unique digital certificate for each new document to be
signed. We demonstrate that private keys associated with these certificates
should be deleted after each signature, eliminating the need to store those
keys. Furthermore, we show that these certificates do not require any
revocation mechanism to be trusted. We analyze the overhead caused by the
frequent generation of new key pairs for each document, provide a security
overview and show the advantages over the traditional model.
