Threshold oblivious pseudorandom function in a key management system

A method for secure processing, the method comprising:

• dividing an Oblivious Pseudorandom Function (OPRF) key to generate a plurality of N partial keys;
• distributing, via a communication system, a respective one of the plurality of N partial keys to a corresponding plurality of N Key Management System (KMS) units, the plurality of N partial keys distributed according to a distribution protocol for storage in the N KMS units;
• receiving, via the communication system and from a threshold number T of the KMS units, a plurality T of partial blinded keys, wherein the plurality T of partial blinded keys are based on processing of a value of a blinded key received by a respective KMS unit and a corresponding stored partial key of the N partial keys;
• combining the plurality T of partial blinded keys into the blinded key;
• processing the blinded key based on the blinding key in accordance with an OPRF unblinding operation to generate a key;
• and
• accessing secure information based on the key.

A system comprises:

• an interface configured to interface and communicate with a communication system;
• memory that stores operational instructions;
• and
• processing circuitry operably coupled to the interface and to the memory, wherein the processing circuitry is configured to execute the operational instructions to:
• transmit, for installation, N distinct partial keys of an Oblivious Pseudorandom Function (OPRF) key to each of N distinct KMS units, using a distribution protocol;
• transmit an Oblivious Key Access Request (OKAR) to at least a threshold number T of the N distinct KMS units;
• perform a validation of the OKAR for at least a threshold number T of the N distinct KMS units;
• for a validated OKAR:
• receive an OKAR response from a corresponding one of the T number of the KMS units, the OKAR response using a root partial key combined with a blinded input to compute a blinded partial-key;
• when at least a threshold number T of validated OKAR responses are received, combine the at least a threshold number T of validated OKAR responses to obtain a blinded OPRF output;
• and
• unblind the blinded OPRF output to recover an OPRF output to be used as a key;
• and
• perform encryption or decryption operations with the key.