An Operations Center (OC) (200) acts as a central key manager and intermediary in securely, reliably and non-repudiably delivering a document (3) from a sender (100) to a recipient (300). The OC (200) acts as a key manager to facilitate the process of strong authentication of the sender (100) and the...http://www.google.de/patents/US6988199?utm_source=gb-gplus-sharePatent US6988199 - Secure and reliable document delivery
