.. _docs/totalcompute/lsc23/security:

Security
========

Assumptions and Delegated Mitigations
-------------------------------------

+-------------------------------+--------------------------------------------------------------+
| ID                            | 01                                                           |
+===============================+==============================================================+
| Assumption                    | Physical attack is out of scope.                             |
+-------------------------------+--------------------------------------------------------------+
| Delegated Mitigation          | The vendor should add protection against any physical attack |
+-------------------------------+--------------------------------------------------------------+
| Impact if assumption is wrong | Unhandled vulnerabilities.                                   |
+-------------------------------+--------------------------------------------------------------+

+------------+---------------------------------------------------------------------------------+
| ID         | 02                                                                              |
+============+=================================================================================+
| Assumption | Part of NOR flash access restriction is controlled by end platform providers.   |
+------------+---------------------------------------------------------------------------------+
| Delegated  | The current hardware and software implementations lack protection to NOR Flash. |
| Mitigation | The vendor should add protection before NOR Flash and program the access        |
|            | restrictions similar to the Memory Side Filter (MSF).                           |
+------------+---------------------------------------------------------------------------------+
| Impact if  | Secure keys/FIP image can be overwritten.                                       |
| assumption |                                                                                 |
| is wrong   |                                                                                 |
+------------+---------------------------------------------------------------------------------+

+-----------------------------------+--------------------------------------------------------------------------------------------------------------------------+
| ID                                | 03                                                                                                                       |
+===================================+==========================================================================================================================+
| Assumption                        | Part of DDR region access restriction is controlled by end platform providers.                                           |
+-----------------------------------+--------------------------------------------------------------------------------------------------------------------------+
| Delegated Mitigation              | The current hardware and software implementations lack protection to DDR.                                                |
|                                   | The vendor should add protection before DDR and program the access restrictions similar to the Memory Side Filter (MSF). |
+-----------------------------------+--------------------------------------------------------------------------------------------------------------------------+
| Impact if the assumption is wrong | Can be overwritten by Malicious software.                                                                                |
+-----------------------------------+--------------------------------------------------------------------------------------------------------------------------+

+-----------------------------------+----------------------------------------------------------------------------------------------------------------------------------------+
| ID                                | 04                                                                                                                                     |
+===================================+========================================================================================================================================+
| Assumption                        | The firmware update capsule is generated from a working set of firmware image blobs (TF-A BL2, SCP BL2, etc.) and not tampered in DDR. |
|                                   | (The Firmware Update Capsule contains the FIP image and additional FWU specific headers.                                               |
|                                   | On the TC SW stack reference design, the update capsule is preloaded manually to the DDR before execution.)                            |
+-----------------------------------+----------------------------------------------------------------------------------------------------------------------------------------+
| Delegated Mitigation              | None.                                                                                                                                  |
+-----------------------------------+----------------------------------------------------------------------------------------------------------------------------------------+
| Impact if the assumption is wrong | Boot hangs.                                                                                                                            |
+-----------------------------------+----------------------------------------------------------------------------------------------------------------------------------------+

+-----------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| ID                                | 05                                                                                                                                                                                           |
+===================================+==============================================================================================================================================================================================+
| Assumption                        | Not using the dummy key provided with the TC software stack for the platform secure boot.                                                                                                    |
+-----------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Delegated Mitigation              | The vendor should follow `RSE guidelines <https://tf-m-user-guide.trustedfirmware.org/design_docs/booting/tfm_secure_boot.html#secure-boot>`_ to create custom keys and securely store them. |
+-----------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Impact if the assumption is wrong | The keys are exposed and the secure boot is compromised.                                                                                                                                     |
+-----------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

+-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| ID                                | 06                                                                                                                                                                                                            |
+===================================+===============================================================================================================================================================================================================+
| Assumption                        | Securely handle debug and trace for production releases.                                                                                                                                                      |
+-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Delegated Mitigation              | The vendor should disable the debug and trace capability for production releases or enable proper debug authentication as recommended by `DEN0034 <https://developer.arm.com/documentation/den0034/latest>`_. |
+-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Impact if the assumption is wrong | Secure data can be exposed. Arbitrary code can be executed.                                                                                                                                                   |
+-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+