Export KEY_ALG as a user build option
The `KEY_ALG` variable is used to select the algorithm for key
generation by `cert_create` tool for signing the certificates. This
variable was previously undocumented and did not have a global default
value. This patch corrects this and also adds changes to derive the
value of `TF_MBEDTLS_KEY_ALG` based on `KEY_ALG` if it not set by the
platform. The corresponding assignment of these variables are also now
removed from the `arm_common.mk` makefile.
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
Change-Id: I78e2d6f4fc04ed5ad35ce2266118afb63127a5a4
diff --git a/docs/user-guide.rst b/docs/user-guide.rst
index 043af63..1502c8c 100644
--- a/docs/user-guide.rst
+++ b/docs/user-guide.rst
@@ -405,6 +405,11 @@
AArch64 and facilitates the loading of ``SP_MIN`` and BL33 as AArch32 executable
images.
+- ``KEY_ALG``: This build flag enables the user to select the algorithm to be
+ used for generating the PKCS keys and subsequent signing of the certificate.
+ It accepts 2 values viz ``rsa``, ``ecdsa``. The default value of this flag
+ is ``rsa``.
+
- ``LDFLAGS``: Extra user options appended to the linkers' command line in
addition to the one set by the build system.
diff --git a/drivers/auth/mbedtls/mbedtls_crypto.mk b/drivers/auth/mbedtls/mbedtls_crypto.mk
index cb81d4d..3819716 100644
--- a/drivers/auth/mbedtls/mbedtls_crypto.mk
+++ b/drivers/auth/mbedtls/mbedtls_crypto.mk
@@ -7,9 +7,15 @@
include drivers/auth/mbedtls/mbedtls_common.mk
# The platform may define the variable 'TF_MBEDTLS_KEY_ALG' to select the key
-# algorithm to use. Default algorithm is RSA.
+# algorithm to use. If the variable is not defined, select it based on algorithm
+# used for key generation `KEY_ALG`. If `KEY_ALG` is not defined or is
+# defined to `rsa`, then set the variable to `rsa`.
ifeq (${TF_MBEDTLS_KEY_ALG},)
- TF_MBEDTLS_KEY_ALG := rsa
+ ifeq (${KEY_ALG}, ecdsa)
+ TF_MBEDTLS_KEY_ALG := ecdsa
+ else
+ TF_MBEDTLS_KEY_ALG := rsa
+ endif
endif
# If MBEDTLS_KEY_ALG build flag is defined use it to set TF_MBEDTLS_KEY_ALG for
diff --git a/make_helpers/defaults.mk b/make_helpers/defaults.mk
index 302d937..8601046 100644
--- a/make_helpers/defaults.mk
+++ b/make_helpers/defaults.mk
@@ -81,6 +81,9 @@
# operations.
HW_ASSISTED_COHERENCY := 0
+# Set the default algorithm for the generation of Trusted Board Boot keys
+KEY_ALG := rsa
+
# Flag to enable new version of image loading
LOAD_IMAGE_V2 := 0
diff --git a/plat/arm/common/arm_common.mk b/plat/arm/common/arm_common.mk
index 20372c2..af94ac2 100644
--- a/plat/arm/common/arm_common.mk
+++ b/plat/arm/common/arm_common.mk
@@ -174,9 +174,6 @@
ifneq (${TRUSTED_BOARD_BOOT},0)
- # By default, ARM platforms use RSA keys
- KEY_ALG := rsa
-
# Include common TBB sources
AUTH_SOURCES := drivers/auth/auth_mod.c \
drivers/auth/crypto_mod.c \
@@ -195,8 +192,6 @@
$(eval $(call FWU_FIP_ADD_IMG,NS_BL2U,--fwu))
- TF_MBEDTLS_KEY_ALG := ${KEY_ALG}
-
# We expect to locate the *.mk files under the directories specified below
ifeq (${ARM_CRYPTOCELL_INTEG},0)
CRYPTO_LIB_MK := drivers/auth/mbedtls/mbedtls_crypto.mk