Patent ID: 6301660
Filing Date: 2001-10-09
Classification: G06F

Abstract:
A computer system, comprising:a protection mechanism for protecting contents of a file wherein the protection mechanism hasat least one viewer program,at least one challenge means associate with said viewer program and said file, anda response means with private keying material that the response means can access,wherein the at least one challenge means has no access to the private keying material, andfurther wherein the response means hasmeans for proving that the response means has access to the private keying material by interacting with the at least one challenge means using an asymmetric cryptographic scheme as a proof,still further wherein the at least one challenge means hasmeans for prohibiting use of some or all of said file's content unless said proof is successful,a distribution system having access to said private keying material of a vendor in said distribution system, said distribution system being authorized to distribute said file wherein said distribution system prohibits said further distribution system from making other distribution systems having access to said private keying material of said vendor,wherein said further distribution system signs said keyfile using a private keying material of said further distribution system,said at least one challenge means validates a certificate of said further distribution system signed using said private keying material of said vendor, said certificate including a public keying material of said further distribution system and using a public keying material of said vendor, andsaid at least one challenge means validates said keyfile using said public keying material of said further distribution system.