An information security system is disclosed having a considerably simplified access control infrastructure. The number of secrets in a computer system domain is reduced to a minimum, yet individual users may still be identified and access to applications may still be individually controlled. The trusted entity in each of a plurality of platforms (100, 200, 202, 203) of the computer system may store an identity secret of the platform (100, 200, 202, 203) and may be trusted to use that secret in conjunction with an information label only when the platform (100, 200, 202, 203) is running the correct software to provide and/or take part in a particular service associated with that information label.