Protecting information processing system secrets from debug attacks
Embodiments of an invention for protecting information processing system secrets from debug attacks are disclosed. In one embodiment, a processor includes storage, a debug unit, and a test access port. The debug unit is to receive a policy from a debug aggregator. The policy is based on a value of a first fuse and has a production mode corresponding to a production value of the first fuse and a debug mode corresponding to a debug value of the fuse. The test access port is to provide access to the storage using a debug command in the debug mode and to prevent access to the storage using the debug command in the production mode.
1. A method comprising:
beginning a reset of a processor;
authenticating a debugger;
determining that the processor is in a production mode based on a production value of a fuse;
sending a policy from a debug aggregator to a test access port in the processor, the policy to indicate that the processor is in the production mode;
preventing access to storage in the processor through the test access port in response to the test access port receiving the policy;
creating a secure enclave after the reset;
storing secrets of the secure enclave in the storage;
configuring the fuse to a debug value;
determining that the processor is in a debug mode based on the debug value of the fuse;
sending the policy from the debug aggregator to the test access port, the policy to indicate that the processor is in the debug mode;
providing access to the storage through the test access port in response to the test access port receiving the policy indicating that the processor is in the debug mode.
2. The method of claim 1 , including setting an indicator during the reset, wherein preventing access to the storage is also in response to the indicator being set.
3. The method of claim 2 , further comprising clearing the storage.
4. The method of claim 3 , further comprising clearing the indicator in response to the storage being cleared.
5. The method of claim 4 , further comprising allowing access to the storage through the test access port in response to the indicator being cleared.
6. The method of claim 2 , further comprising operating on secrets in the storage by the processor in response to the indicator being set.
7. The method of claim 6 , further comprising clearing the indicator after operating on the secrets.