KEY ISSUER, KEY CARRIER, ACCESS UNIT AND METHODS PERFORMED IN SAID UNITS

摘要

The present invention related to a key issuer for an access system, a key carrier and an access unit of an access system. The key issuer is arranged to issue user keys for access to one or a plurality said access units. Each user key comprises a signature for validation of the key issuer and credential information for verification of the user of the user key. The key issuer is arranged to provide the signature using a private encryption key of the key issuer. The key issuer is arranged to encrypt the credential information using a public key of the access unit.