net: tls_credentials: Add TLS credential backend for nrf_modem

Add TLS credential backend for nrf_modem so that TLS credentials will
be sent to the nRF modem for persistent storage and to be used in
TLS connections.

Signed-off-by: Joakim Andersson <[email protected]>

Author: joerchan

subsys/net/lib/CMakeLists.txt

@@ -30,6 +30,7 @@ add_subdirectory_ifdef(CONFIG_FTP_CLIENT ftp_client)
 add_subdirectory_ifdef(CONFIG_COAP_UTILS coap_utils)
 add_subdirectory_ifdef(CONFIG_LWM2M_CLIENT_UTILS lwm2m_client_utils)
 add_subdirectory_ifdef(CONFIG_WIFI_CREDENTIALS wifi_credentials)
+add_subdirectory_ifdef(CONFIG_TLS_CREDENTIALS tls_credentials)
 add_subdirectory_ifdef(CONFIG_SOFTAP_WIFI_PROVISION softap_wifi_provision)
 add_subdirectory_ifdef(CONFIG_WIFI_MGMT_EXT wifi_mgmt_ext)
 add_subdirectory_ifdef(CONFIG_WIFI_READY_LIB wifi_ready)

subsys/net/lib/Kconfig

@@ -41,6 +41,7 @@ rsource "icalendar_parser/Kconfig"
 rsource "ftp_client/Kconfig"
 rsource "coap_utils/Kconfig"
 rsource "lwm2m_client_utils/Kconfig"
+rsource "tls_credentials/Kconfig"
 rsource "wifi_credentials/Kconfig"
 rsource "softap_wifi_provision/Kconfig"
 rsource "wifi_mgmt_ext/Kconfig"

subsys/net/lib/tls_credentials/CMakeLists.txt

@@ -0,0 +1,13 @@
+#
+# Copyright (c) 2025 Nordic Semiconductor
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+zephyr_library()
+
+zephyr_library_include_directories(${ZEPHYR_BASE}/subsys/net/lib/tls_credentials)
+
+zephyr_library_sources_ifdef(CONFIG_TLS_CREDENTIALS_BACKEND_NRF_MODEM
+  tls_credentials_nrf_modem.c
+)

subsys/net/lib/tls_credentials/Kconfig

@@ -0,0 +1,28 @@
+# Copyright (c) 2025 Nordic Semiconductor
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+if TLS_CREDENTIALS
+
+config TLS_MAX_CREDENTIALS_NUMBER
+	# Increase default maximum number of TLS credentials that can be registered.
+	default 20 if TLS_CREDENTIALS_BACKEND_NRF_MODEM
+
+choice TLS_CREDENTIALS_BACKEND
+	depends on TLS_CREDENTIALS
+	default TLS_CREDENTIALS_BACKEND_NRF_MODEM if NRF_MODEM_LIB
+	help
+	  TLS credentials management backend implementation.
+
+config TLS_CREDENTIALS_BACKEND_NRF_MODEM
+	bool "Use modem credentials storage as backend"
+	depends on MODEM_KEY_MGMT
+	help
+	  TLS credentials management backend using the nrf modem key management API to store
+	  credentials and keep entries across system reboot.
+	  Entries are loaded from the modem at boot, and can then be used in socket connections.
+
+endchoice
+
+endif # TLS_CREDENTIALS