Abstract: Apparatuses and methods for memory protection are disclosed. A memory protection apparatus is interposed between a system cache and a memory system. The apparatus comprises encryption circuitry, which encrypts data item in dependence on encryption metadata and decrypts encrypted data items in dependence on the encryption metadata. In response to a change in a metadata item of the encryption metadata, when no cached copy of an affected data item is currently in the system cache, the affected data item is retrieved from the memory system, re-encrypted using the updated metadata item and returned to the memory system. When there is a cached copy, in dependence on update control data, the copy is retrieved from the system cache, encrypted using the updated metadata item and written out to the memory system.

Abstract: There is provided a memory protection unit configured to maintain region metadata associated with storage regions of off-chip storage and protection metadata associated with each of the storage regions. The protection metadata is stored in the off-chip storage, and the region metadata encodes whether each of the storage regions belongs to a set of protected storage regions or to a set of unprotected storage regions and encodes information indicating corresponding protection metadata associated with each storage region. The memory protection unit is configured to update the region metadata in response to a region update request identifying a given storage region for which the region metadata is to be modified and to dynamically adjust an amount of memory required to store protection metadata associated with the set of protected storage regions in response to the update to the region metadata.