Method and system for an efficient shared-derived secret provisioning mechanism

A system for provisioning a device with an embedded secret comprising:

• a processor;
• a secure execution controller;
• first and second embedded key hardware registers in the device;
• and
• at least one non-transitory computer-readable storage medium storing computer instructions translatable by the processor to perform:
• providing a pair of keyed hash functions in the device;
• receiving a first external reference code from a source external to the device;
• permanently writing a known value into the first embedded key hardware register in the device to create an embedded secret;
• and
• creating a second external reference code by hashing the received first external reference code using one of the keyed hash functions, wherein the keyed hash function is keyed using the embedded secret created by the permanent writing of the known value into the first embedded key hardware register wherein creating the second external reference code includes at device power-up, transferring the contents of the first embedded key register to the second embedded key register where the contents of the second embedded key register are provided as a key to the one of the keyed hash functions, and wherein at device power-up, the contents of the second embedded key register are updated with a value derived from the known value permanently written in the first embedded key register;
• and
• providing an internal MAC output by hashing a message input using the contents of the second embedded key register as the key to one of the keyed hash functions.

A method for provisioning a device with a group secret key that is sharable with similar devices comprising:

• providing a first embedded key hardware register in the device;
• providing a second embedded key hardware register in the device;
• providing a pair of keyed hash functions in the device;
• permanently writing a known value into the first embedded key hardware register in the device to create an embedded secret;
• at device power-up, transferring the contents of the first embedded key register to the second embedded key register, wherein the contents of the second embedded key register are provided as a key to one of the pair of keyed hash functions;
• after device power-up, updating the contents of the second embedded key register with a value derived from the known value permanently written in the first embedded key register;
• providing an internal MAC output by hashing a message input using a derivation of the contents of the first embedded key register as the key to one of the pair of keyed hash functions;
• receiving an external message input from a source external to the device;
• and
• using the internal MAC output and the external message input to derive a group secret key, wherein the group secret key includes secret portion and a public portion, and wherein the public portion of the group secret key identifies a group to which the device belongs.