Patent ID: 7801302

Claim:
A cryptographic method in which a sender encrypts and sends a message to a recipient for decryption by a trusted party, the sender being in possession of a public key for which there exists a corresponding private key held by the trusted party, the method comprising: the sender employing a computing apparatus to encrypt the message using a modified public key that results from exponentiating at least one element of the public key using as exponent a hash of a string that comprises information concerning at least one action to be taken by the trusted party; the recipient receiving the encrypted message and said string and passing them to the trusted party; the trusted party employing a computing apparatus to decrypt the encrypted message using a modified private key that results from using the string to modify the private key to complement the modified public key; and the trusted party returning the decrypted message to the recipient after carrying out said at least one action with a satisfactory conclusion.