PRIVACY-PROTECTED TRANSFER OF ELECTRONIC INFORMATION

Cryptographic apparatus and means are disclosed for each of three types of participants in an electronic system for privacy-protected transfer of certified information. This invention reveals protocols that improve efficiency and security in such systems, and allows a variety of useful extensions in functionality without difficulty. This is achieved by a restrictive blind signature protocol in combination with a testing protocol. The restrictive blind signature protocol allows the certifying party to encode data into certified information that it provides to a receiving party, such that it cannot be altered or modified by the receiving party. The testing protocol enables parties to prove a variety of characteristics about the encoded data in their certified information.