US Patent 10931443 Hierarchical key management based on bitwise XOR operations

A computer-implemented method manages cryptographic objects in a hierarchical key management system including a hardware security module (HSM), which institutes a key hierarchy extending from a ground level l0. Clients interact with the HSM to obtain cryptographic objects. A request is received from one of the clients for an object at a given level ln of the hierarchy (above the ground level l0). A binary representation of the object is accessed as a primary bit pattern p0, at the HSM and said pattern is scrambled via a bitwise XOR operation. The latter operates, on the one hand, on the primary bit pattern p0 and, on the other hand, on a control bit pattern pc that is a binary representation of an access code of the same length as said primary bit pattern p0. The pattern pc is obtained based on that given level ln of the hierarchy.