Key revocation

1. A system for key revocation comprising:

a processor;

an embedded controller;

a non-volatile memory storing a system instruction signing key authorization data element, wherein the data element includes a system instruction signing key, a signing key number and a signature; and

the embedded controller including:

a plurality of root keys to verify the data element; and

a one-time programmable (OTP) memory and a key among the plurality of root keys that is revocable using the OTP memory, the OTP memory including a neverlock bit, wherein:

revocation of the key permanently prevents the embedded controller from utilizing the key, wherein the revocation is performed by breaking a fuse associated with the key; and

the key is automatically revoked within a threshold period of time from a verification unless a neverlock bit is verified to be set such that revocation of the key is prevented.

2. The system of claim 1 , wherein the embedded controller further includes a boot loader to authorize the system instruction signing key by verifying the signature of the data element.

3. The system of claim 1 , wherein the embedded controller authorizes the system instruction signing key using a key among the plurality of root keys and by verifying the signature in the data element.

4. The system of claim 1 , wherein the embedded controller includes a lock bit to revoke a key among the plurality of root keys.

5. The system of claim 1 , wherein the data element includes a public portion of a system signing key; and

wherein the embedded controller verifies the signature and the signing key number prior to startup of the processor.

6. The system of claim 1 , further comprising the embedded controller to permanently revoke access to a key among the plurality of root keys responsive to modification of a lock bit in the OTP memory.

7. The system of claim 1 , wherein the embedded controller includes access to a plurality of locked OTP bits, wherein a locked OTP bit identifies a key among the plurality of root keys that is permanently revoked.

8. The system of claim 1 , wherein the OTP memory includes a lock bit indicating whether the key is permanently revoked, and wherein the embedded controller is to automatically change, after a specified amount of time, a value of the lock bit to permanently revoke the key.

9. A method of key revocation comprising:

validating system instructions in a private non-volatile memory by:

identifying, using a bootloader on an embedded controller, a system instruction signing key authorization data element stored in the private non-volatile memory;

verifying, using the bootloader, a signature generated by a plurality of system instruction signing root keys and stored in the data element; and

verifying a value of a neverlock bit stored in a one-time programmable (OTP) memory, the value associated with prevent permanent revocation of a key among a plurality of root keys for verification of the data element, wherein:

the key is permanently and automatically revoked within a threshold period of time of the verification unless the value is determined to be set; and

the key is permanently revoked by breaking a fuse associated with the key; and

authenticating the system instructions for access of a shared non-volatile memory by a processor, in response to the validation of the system instructions.

10. The method of claim 9 , wherein verifying the value stored in the OTP memory includes determining the key has been permanently revoked.

11. The method of claim 9 , wherein validating system instructions in the private non-volatile memory includes attempting to validate a system instruction signing key and a test key, and if neither work, then determining that the signature is invalid.

12. A non-transitory computer readable medium storing instructions executable by an embedded controller to:

validate system instructions in a private non-volatile memory by:

identifying, using a bootloader on an embedded controller, a system instruction signing key authorization data element stored in the private non-volatile memory;

verifying, using the bootloader, a signature by a system instruction signing key and stored in the data element;

verifying, using the bootloader, a key number in the data element using a value stored in the OTP memory and associated with revocation of a test key, wherein:

permanent revocation of the test key is automatically performed unless a neverlock bit stored in the OTP memory indicates a prevention of the automatic revocation; and

the test key is permanently revoked by breaking a fuse associated with the key to permanently revoke the key; and

authenticate the system instructions for access of a shared non-volatile memory by a processor, in response to the validation of the system instructions.

13. The non-transitory computer readable medium of claim 12 , further including the embedded controller to permanently revoke the test key by receiving a modification of the OTP memory.

14. The non-transitory computer readable medium of claim 13 , further including the embedded controller to invalidate the system instructions in response to determining that the key number corresponds to a revoked key.

15. The method of claim 12 , wherein the permanent revocation is automatically performed within a threshold period of time.