Patent ID: 7693286

Claim:
A method comprising: generating a Direct Proof family key pair, including a family public key, for a class of approved devices; generating first and additional encrypted data structures respectively for first and additional devices in the class, the first and additional encrypted data structures respectively comprising first and additional private keys and private key digests based at least in part on the Direct Proof family key pair, wherein the family public key can be used to verify that a signature created by any of the first and additional private keys corresponds to at least one device in the class without determining which specific device created the signature; generating first and additional identifiers respectively for the first and additional encrypted data structures based respectively on pseudo-random values for the first and additional devices; storing the first and additional identifiers and encrypted data structures in a signed group record on a removable storage medium; and storing a group number corresponding to the signed group record and a different one of the pseudo-random values into non-volatile storage in each of the first and additional devices, without storing the first and additional private keys respectively in the first and additional devices.