Patent attributes
In a general aspect, a digital certificate can be used with multiple cryptography systems (“cryptosystems”). In some cases, the digital certificate includes a public key field, which contains a first public key of an entity associated with a first cryptosystem. The digital certificate includes a signature value field, which contains a first digital signature of a certificate authority associated with the first cryptosystem. The digital certificate includes an extension. The extension contains a second public key of the entity, a second digital signature of the certificate authority, or both, associated with a second cryptosystem. The extension contains a policy field that includes instructions for processing the fields associated with the second cryptosystem.
