Assymetric structured key recovering using oblivious pseudorandom function

A method for use in a key management system (KMS), the method comprising:

• maintaining, by a server device including a processor and associated memory, structured key parameters associated with a structured key;
• maintaining, by the server device, a generating procedure associated with the structured key, the generating procedure configured to produce the structured key from an Oblivious Pseudorandom Function (OPRF) output, and the structured key parameters;
• receiving, by the server device from a requesting computing device, a blinded value associated with the structured key, wherein the blinded value is generated at the requesting computer device based on an input value unknown to the server device;
• processing, by the server device, the blinded value using an OPRF secret to generate a blinded OPRF output, wherein the OPRF secret is unknown to the requesting computing device;
• and
• returning, by the server device, the blinded OPRF output, the generating procedure, and the structured key parameters to the requesting computing device, for generation of the structured key by the requesting computing device.

A method comprising:

• receiving, at a key management server configured to implement a key management system (KMS), a blinded value associated with a structured key managed by the key management server, the blinded value received from a requesting device via a communications network;
• obtaining, by the key management server, a generating procedure associated with the structured key;
• obtaining, by the key management server, structured key parameters associated with the structured key;
• processing, by key management server, the blinded value using an Oblivious Pseudorandom Function (OPRF) secret to generate a blinded OPRF output;
• and
• returning the blinded OPRF output, the generating procedure, and the structured key parameters to the requesting device, for generation of the structured key by the requesting device.