<heading lvl="0">Abstract of Disclosure< / heading> Before use, a
population of tamper-resistant cryptographic
enforcement devices is partitioned into groups and issued one or more group keys. Each tamper-resistant device contains multiple computational units to control access to
digital content. One of the computational units within each tamper-resistant device communicates with another of the computational units acting as an interface control processor, and serves to protect the contents of a nonvolatile memory from unauthorized access or modification by other portions of the tamper-resistant device, while performing cryptographic computations using the memory contents. Content providers enforce viewing privileges by transmitting encrypted rights keys to a large number of recipient devices. These recipient devices process received messages using the protected
processing environment and memory space of the
secure unit. The
processing result depends on whether the recipient device was specified by the content provider as authorized to view some encrypted
digital content. Authorized recipient devices can use the
processing result in decrypting the content, while unauthorized devices cannot decrypt the content. A related aspect of the invention provides for securing computational units and controlling attacks. For example, updates to the nonvolatile memory, including program updates, are supported and protected via a cryptographic unlocking and validation process in the
secure unit, which can include
digital signature verification.