docs: Update docs with firmware encryption feature
Update documentation with optional firmware encryption feature.
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Change-Id: I26691b18e1ee52a73090954260f26f2865c4e05a
diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index af4895e..f138feb 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -263,6 +263,22 @@
platform hook needs to be implemented. The value is passed as the last
component of the option ``-fstack-protector-$ENABLE_STACK_PROTECTOR``.
+- ``ENCRYPT_BL31``: Binary flag to enable encryption of BL31 firmware. This
+ flag depends on ``DECRYPTION_SUPPORT`` build flag which is marked as
+ experimental.
+
+- ``ENCRYPT_BL32``: Binary flag to enable encryption of Secure BL32 payload.
+ This flag depends on ``DECRYPTION_SUPPORT`` build flag which is marked as
+ experimental.
+
+- ``ENC_KEY``: A 32-byte (256-bit) symmetric key in hex string format. It could
+ either be SSK or BSSK depending on ``FW_ENC_STATUS`` flag. This value depends
+ on ``DECRYPTION_SUPPORT`` build flag which is marked as experimental.
+
+- ``ENC_NONCE``: A 12-byte (96-bit) encryption nonce or Initialization Vector
+ (IV) in hex string format. This value depends on ``DECRYPTION_SUPPORT``
+ build flag which is marked as experimental.
+
- ``ERROR_DEPRECATED``: This option decides whether to treat the usage of
deprecated platform APIs, helper functions or drivers within Trusted
Firmware as error. It can take the value 1 (flag the use of deprecated
@@ -287,6 +303,18 @@
- ``FWU_FIP_NAME``: This is an optional build option which specifies the FWU
FIP filename for the ``fwu_fip`` target. Default is ``fwu_fip.bin``.
+- ``FW_ENC_STATUS``: Top level firmware's encryption numeric flag, values:
+
+ ::
+
+ 0: Encryption is done with Secret Symmetric Key (SSK) which is common
+ for a class of devices.
+ 1: Encryption is done with Binding Secret Symmetric Key (BSSK) which is
+ unique per device.
+
+ This flag depends on ``DECRYPTION_SUPPORT`` build flag which is marked as
+ experimental.
+
- ``GENERATE_COT``: Boolean flag used to build and execute the ``cert_create``
tool to create certificates as per the Chain of Trust described in
:ref:`Trusted Board Boot`. The build system then calls ``fiptool`` to