Protecting contents of storage in a computer system from unauthorized access. The computer system comprises one or more processing units sharing the storage, the processing units each having at least one processor cache. Each processing unit respectively encrypts or decrypts, with a protected section key in the chip cache, data transferred between its processor cache and the protected section, and each processing unit respectively encrypts or decrypts, with a segment key, data transferred between the chip cache and the storage, when data relates to a specific segment of the storage.