Method and apparatus for multi-key total memory encryption based on dynamic key derivation

A method to be performed by a processor comprising a memory controller to use cryptographic circuitry to encrypt and decrypt data, and storage to store a plurality of key splits and a plurality of full encryption keys, the method comprising:

• fetching, using fetch circuitry, an instruction;
• decoding, using decode circuitry, the fetched instruction specifying an opcode, an address, and a key identifier, the opcode indicating the processor is to use the address to determine whether to use an explicit key, in which case the processor is to use the key identifier to select a cryptographic key among the plurality of full encryption keys, and, otherwise, the processor is to dynamically derive the cryptographic key by using the key identifier to select a key split among the plurality of key splits, and provide the key split and a root key to a key derivation function (KDF) implemented by the memory controller, which is further to use the cryptographic key with the encryption circuitry to perform a cryptographic operation on an encrypted memory location;
• and
• executing the instruction, using execution circuitry, as per the opcode,
• wherein each of the key splits requires less storage than each of the full encryption keys.

A non-transitory computer-readable medium containing instructions to which a processor comprising a memory controller to use cryptographic circuitry to encrypt and decrypt data, a memory controller to use cryptographic circuitry to encrypt and decrypt data, and storage to store a plurality of key splits and a plurality of full encryption keys is to respond by:

• fetching, using fetch circuitry, an instruction;
• decoding, using decode circuitry, the fetched instruction specifying an opcode, an address, and a key identifier, the opcode indicating the processor is to use the address to determine whether to use an explicit key, in which case the processor is to use the key identifier to select a cryptographic key among the plurality of full encryption keys, and, otherwise, the processor is to dynamically derive the cryptographic key by using the key identifier to select a key split among the plurality of key splits, and provide the key split and a root key to a key derivation function (KDF) implemented by the memory controller, which is further to use the cryptographic key with the encryption circuitry to perform a cryptographic operation on an encrypted memory location;
• and
• executing the instruction, using execution circuitry, as per the opcode,
• wherein each of the key splits requires less storage than each of the full encryption keys.