On November 12, 2009 the US Patent & Trademark Office published two patent applications from Apple that reveal yet another chapter in iPhone security. Apple's patent generally relates to authentication and more specifically relates to a system and method of providing authentication based on a weighted average principal. Apple's iPhone security includes protection of digital content from theft or corruption and also addresses the preservation of system availability. In many communication systems, the weakest link in security is not the encrypted data but rather cryptographic key management and handling. Unauthorized users may gain access to sensitive data when key management is not performed securely. During Apple's WWDC 2009, Phil Schiller stated that businesses had asked for hardware encryption and that all iPhone 3G-S models would now incorporate Apple's new security features. These patents mark the fourth and fifth such iPhone related security patents since September and demonstrate Apple's commitment to the enterprise market. Apple's patent shrouds their technology under what is known in the industry as the "black box" approach.