https://devzone.nordicsemi.com/f/nordic-q-a/102687/undefined-reference-to-rsa_pub_key_lenD:\ncs\v2.4.0\bootloader\mcuboot\samples\zephyr\hello-world&gt;west build -b nrf5340dk_nrf5340_cpuapp -- west build: generating a build system ... -- Configuring done -- Generating done -- Build files have been written to: D:/ncs/v2.4.0/bootloader/mcubooten-USTelligent Community 13Thu, 10 Aug 2023 07:51:11 GMThttps://devzone.nordicsemi.com/thread/440638?ContentTypeID=1Thu, 10 Aug 2023 07:51:11 GMT137ad170-7792-4731-bb38-c0d22fbe4515:41a83ff1-c46c-4996-b385-64c15b6ab7d4Sigurd<p>I suggest&nbsp;CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/440607?ContentTypeID=1Thu, 10 Aug 2023 02:53:46 GMT137ad170-7792-4731-bb38-c0d22fbe4515:89774770-a3e5-4002-bfbb-ce733f5ee270snowuyl<p>Thanks for your reply! From <a id="" href="https://docs.mcuboot.com/imgtool.html,">https://docs.mcuboot.com/imgtool.html,</a> <code>imgtool </code>tool currently supports rsa-2048, rsa-3072, ecdsa-p256 and ed25519 keys. Which key do you suggest?</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/440495?ContentTypeID=1Wed, 09 Aug 2023 12:21:30 GMT137ad170-7792-4731-bb38-c0d22fbe4515:9bded08c-f715-42b3-916c-83ba95ce715aSigurd<p>Hi,</p> <p>Try setting this config:&nbsp;CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256</p> <p>See this for more info:</p> <p>&nbsp;<a href="https://devzone.nordicsemi.com/f/nordic-q-a/80094/undefined-reference-to-rsa_pub_key-when-config_boot_signature_key_file-is-defined/332516">RE: Undefined reference to rsa_pub_key when CONFIG_BOOT_SIGNATURE_KEY_FILE is defined</a>&nbsp;</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/440397?ContentTypeID=1Wed, 09 Aug 2023 05:55:53 GMT137ad170-7792-4731-bb38-c0d22fbe4515:ccf2b242-664f-4d90-9a26-af3400ebfeb6snowuyl<p><a href="https://devzone.nordicsemi.com/cfs-file/__key/communityserver-discussions-components-files/4/undefined_5F00_reference_5F00_to_5F00_rsa_5F00_pub_5F00_key-and-rsa_5F00_pub_5F00_key_5F00_len.zip">devzone.nordicsemi.com/.../undefined_5F00_reference_5F00_to_5F00_rsa_5F00_pub_5F00_key-and-rsa_5F00_pub_5F00_key_5F00_len.zip</a></p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/440396?ContentTypeID=1Wed, 09 Aug 2023 05:54:45 GMT137ad170-7792-4731-bb38-c0d22fbe4515:4faad051-940a-417a-8b2f-e32f4b33ead3snowuyl<p><a href="https://devzone.nordicsemi.com/cfs-file/__key/communityserver-discussions-components-files/4/7612.hello_2D00_world.zip">devzone.nordicsemi.com/.../7612.hello_2D00_world.zip</a></p><div style="clear:both;"></div>