[nrf toup] Migrate DAC to CRACEN KMU on nRF54L devices

On nRF54L devices we can use KMU to store the DAC private key,
and allow using it directly by CRACEN.
By default the DAC private key is encrypted so it needs
4 KMU slots.

Signed-off-by: Arkadiusz Balys <arkadiusz.balys@nordicsemi.no>

Author: ArekBalysNordic

config/nrfconnect/chip-module/Kconfig

@@ -365,15 +365,47 @@ config CHIP_ENABLE_READ_CLIENT
 	  Disabling this config can save flash and RAM space.
 
 config CHIP_CRYPTO_PSA_MIGRATE_DAC_PRIV_KEY
-	bool "Migrate DAC private key from factory data to PSA ITS"
+	bool "Migrate DAC private key from factory data to a secure storage"
 	depends on CHIP_CRYPTO_PSA
 	depends on CHIP_FACTORY_DATA
+
+choice CHIP_CRYPTO_PSA_DAC_PRIV_KEY_MIGRATION_DEST
+	prompt "Destination for DAC private key migration"
+	default CHIP_CRYPTO_PSA_DAC_PRIV_KEY_ITS
+
+config CHIP_CRYPTO_PSA_DAC_PRIV_KEY_ITS
+	bool "Migrate DAC private key from factory data to PSA ITS"
 	help
 	  Move DAC private key from the factory data set to the PSA ITS secure storage
 	  and remove it. After the first boot of the device the DAC private key will be moved
 	  to the PSA ITS secure storage and will not be available in the factory data anymore.
 	  It will be overwritten in the factory data set by zeros.
 
+config CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU
+	bool "Migrate DAC private key from factory data to CRACEN KMU"
+	depends on CRACEN_LIB_KMU
+	help
+	  Move DAC private key from the factory data set to the CRACEN Key Management Unit (KMU) secure
+	  storage and remove it. After the first boot of the device the DAC private key will be
+	  moved to the CRACEN KMU secure storage and will not be available in the factory data anymore.
+	  It will be overwritten in the factory data set by zeros.
+
+endchoice
+
+config CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU_SLOT_ID
+	int "Destination DAC private key slot ID inside CRACEN KMU"
+	depends on CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU
+	range 0 179 # Allow using the application usage space only
+	default 176 if CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU_ENCRYPTED
+	default 178
+
+config CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU_ENCRYPTED
+	bool "Encrypt DAC private key in CRACEN KMU"
+	default y
+	depends on CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU
+	help
+	  Encrypt the DAC private key in the CRACEN KMU secure storage.
+
 config CHIP_PERSISTENT_SUBSCRIPTIONS
 	default n
 	# selecting experimental for this feature since there is an issue with multiple controllers.

config/nrfconnect/chip-module/Kconfig.defaults

@@ -433,6 +433,11 @@ config MBEDTLS_SSL_COOKIE_C
 config MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH
     default y
 
+# Use KMU for storing DAC private key for nRF54LX devices
+choice CHIP_CRYPTO_PSA_DAC_PRIV_KEY_MIGRATION_DEST
+    default CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU if SOC_SERIES_NRF54LX
+endchoice
+
 # ==============================================================================
 # Logging configuration
 # ==============================================================================

src/platform/nrfconnect/FactoryDataProvider.cpp

@@ -26,6 +26,10 @@
 
 #include <lib/support/logging/CHIPLogging.h>
 
+#ifdef CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU
+#include <cracen_psa_kmu.h>
+#endif
+
 #ifdef CONFIG_CHIP_CRYPTO_PSA
 #include <lib/support/ScopedBuffer.h>
 #include <psa/crypto.h>
@@ -139,26 +143,43 @@ CHIP_ERROR FactoryDataProvider<FlashFactoryData>::MoveDACPrivateKeyToSecureStora
         {
             ChipLogProgress(DeviceLayer, "Found DAC Private Key in factory data set. Copying to secure storage...");
 
+#if defined(CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_ITS)
             // Remove the key if any exists and can be corrupted.
             psa_destroy_key(mDACPrivKeyId);
+#endif
 
             psa_reset_key_attributes(&attributes);
             psa_set_key_type(&attributes, PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
             psa_set_key_bits(&attributes, kDACPrivateKeyLength * 8);
-            psa_set_key_algorithm(&attributes, PSA_ALG_ECDSA(PSA_ALG_SHA_256));
+            psa_set_key_algorithm(&attributes, PSA_ALG_ECDSA(PSA_ALG_ANY_HASH));
+            psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_SIGN_MESSAGE);
 #ifdef CONFIG_CHIP_CRYPTO_PSA_MIGRATE_DAC_PRIV_KEY
+#if defined(CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_ITS)
             psa_set_key_lifetime(&attributes, PSA_KEY_LIFETIME_PERSISTENT);
             psa_set_key_id(&attributes, mDACPrivKeyId);
+#elif defined(CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU)
+            psa_set_key_lifetime(
+                &attributes,
+                PSA_KEY_LIFETIME_FROM_PERSISTENCE_AND_LOCATION(PSA_KEY_PERSISTENCE_DEFAULT, PSA_KEY_LOCATION_CRACEN_KMU));
+            psa_set_key_id(&attributes,
+                           PSA_KEY_HANDLE_FROM_CRACEN_KMU_SLOT(
+#ifdef CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU_ENCRYPTED
+                               CRACEN_KMU_KEY_USAGE_SCHEME_ENCRYPTED,
+#else
+                               CRACEN_KMU_KEY_USAGE_SCHEME_RAW,
+#endif // CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU_ENCRYPTED
+                               CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU_SLOT_ID));
+#endif // CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_ITS || CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU
 #else
             psa_set_key_lifetime(&attributes, PSA_KEY_LIFETIME_VOLATILE);
-#endif
-            psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_SIGN_MESSAGE);
-
-            VerifyOrReturnError(psa_import_key(&attributes, reinterpret_cast<uint8_t *>(mFactoryData.dac_priv_key.data),
-                                               kDACPrivateKeyLength, &mDACPrivKeyId) == PSA_SUCCESS,
-                                CHIP_ERROR_INTERNAL);
+#endif // CONFIG_CHIP_CRYPTO_PSA_MIGRATE_DAC_PRIV_KEY
         }
 
+        psa_status_t status = psa_import_key(&attributes, reinterpret_cast<uint8_t *>(mFactoryData.dac_priv_key.data),
+                                             mFactoryData.dac_priv_key.len, &mDACPrivKeyId);
+        ChipLogProgress(DeviceLayer, "xD3.5 %d", status);
+        VerifyOrReturnError(status == PSA_SUCCESS, CHIP_ERROR_INTERNAL);
+
 #ifdef CONFIG_CHIP_CRYPTO_PSA_MIGRATE_DAC_PRIV_KEY
 #ifdef CONFIG_CHIP_FACTORY_RESET_ERASE_SETTINGS
 #error "Do not use both CONFIG_CHIP_FACTORY_RESET_ERASE_SETTINGS and CONFIG_CHIP_CRYPTO_PSA_MIGRATE_DAC_PRIV_KEY kconfig options " \
@@ -275,8 +296,19 @@ CHIP_ERROR FactoryDataProvider<FlashFactoryData>::SignWithDeviceAttestationKey(c
 
 #ifdef CONFIG_CHIP_CRYPTO_PSA
     size_t outputLen = 0;
+#if defined(CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_ITS)
+    psa_key_id_t keyId = mDACPrivKeyId;
+#elif defined(CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU)
+    psa_key_id_t keyId = static_cast<psa_key_id_t>(PSA_KEY_HANDLE_FROM_CRACEN_KMU_SLOT(
+#ifdef CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU_ENCRYPTED
+        CRACEN_KMU_KEY_USAGE_SCHEME_ENCRYPTED,
+#else
+        CRACEN_KMU_KEY_USAGE_SCHEME_RAW,
+#endif // CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU_ENCRYPTED
+        CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU_SLOT_ID));
+#endif // CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_ITS || CONFIG_CHIP_CRYPTO_PSA_DAC_PRIV_KEY_KMU
 
-    psa_status_t err = psa_sign_message(mDACPrivKeyId, PSA_ALG_ECDSA(PSA_ALG_SHA_256), messageToSign.data(), messageToSign.size(),
+    psa_status_t err = psa_sign_message(keyId, PSA_ALG_ECDSA(PSA_ALG_SHA_256), messageToSign.data(), messageToSign.size(),
                                         signature.Bytes(), signature.Capacity(), &outputLen);
 
     VerifyOrReturnError(!err, CHIP_ERROR_INTERNAL);