[nrf noup] kconfig: enable external crypto config

Remove undefined dependency and add overlay file
for building minimal mcuboot with exeternal crypto.

Signed-off-by: Håkon Øye Amundsen <[email protected]>

(cherry picked from commit e473ee3)
(cherry picked from commit 4d1b74b)
(cherry picked from commit a2c9384)
Signed-off-by: Ioannis Glaropoulos <[email protected]>
(cherry picked from commit fbd3e7a)
Signed-off-by: Johann Fischer <[email protected]>
(cherry picked from commit ca4d049)
Signed-off-by: Trond Einar Snekvik <[email protected]>
(cherry picked from commit 0c9464d)

Author: hakonfam

boot/zephyr/Kconfig

@@ -128,7 +128,6 @@ config BOOT_ECDSA_CC310
 config BOOT_NRF_EXTERNAL_CRYPTO
 	bool "Use Shared Crypto from bootloader"
 	select BOOT_USE_NRF_EXTERNAL_CRYPTO
-	depends on SECURE_BOOT_CRYPTO_CLIENT
 
 endchoice # Ecdsa implementation
 

boot/zephyr/overlay-minimal-external-crypto.conf

@@ -0,0 +1,46 @@
+#
+# Copyright (c) 2020 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-BSD-5-Clause-Nordic
+#
+
+# These configurations should be used when using nrf/samples/bootloader
+# as the immutable bootloader (B0), and MCUBoot as the second stage updateable
+# bootloader. With this configuration, MCUBoot will re-use the crypto
+# functionality from B0, and fit within 16kB.
+
+CONFIG_NCS_SAMPLES_DEFAULTS=n
+CONFIG_LOG=n
+CONFIG_BOOT_BANNER=n
+CONFIG_PRINTK=n
+CONFIG_CONSOLE=n
+CONFIG_UART_CONSOLE=n
+CONFIG_SERIAL=n
+CONFIG_SECURE_BOOT_DEBUG=n
+CONFIG_ASSERT=n
+CONFIG_RESET_ON_FATAL_ERROR=n
+CONFIG_REBOOT=n
+CONFIG_GPIO=n
+CONFIG_CLOCK_CONTROL=n
+CONFIG_MINIMAL_LIBC_MALLOC=n
+CONFIG_MINIMAL_LIBC_CALLOC=n
+CONFIG_MINIMAL_LIBC_REALLOCARRAY=n
+CONFIG_SIZE_OPTIMIZATIONS=y
+CONFIG_NO_RUNTIME_CHECKS=y
+CONFIG_CONSOLE_HANDLER=n
+CONFIG_NRF_RTC_TIMER=n
+CONFIG_SYS_CLOCK_EXISTS=n
+
+# Set ECDSA as signing mechanism
+CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256=y
+
+# Use crypto backend from B0
+CONFIG_BOOT_NRF_EXTERNAL_CRYPTO=y
+CONFIG_SECURE_BOOT_CRYPTO=y
+CONFIG_SB_CRYPTO_CLIENT_ECDSA_SECP256R1=y
+CONFIG_SB_CRYPTO_CLIENT_SHA256=y
+CONFIG_BL_SHA256_EXT_API_REQUIRED=y
+CONFIG_BL_SECP256R1_EXT_API_REQUIRED=y
+
+# Set 16kB as flash size
+CONFIG_PM_PARTITION_SIZE_MCUBOOT=0x3e00