NXP Manufacturing data

By default, the example application is configured to use generic test certificates and provisioning data embedded with the application code. It is possible for a final stage application to generate its own manufacturing data using the procedure described below.

1. Prerequisites

Generate build files from Matter root folder by running:

gn gen out

Build chip-cert tool:

ninja -C out chip-cert

Build spake2p tool:

ninja -C out spake2p

2. Generate

a. Certificates

To generate the different certificates, NXP provides a Python script scripts/tools/nxp/generate_certs.py. This script will always generate the PAI and DAC certificates/keys. It can also generate the Certification Declaration and the PAA certificate/key depending on the parameters.

Parameter	Description	Type	Required
`--chip_cert_path`	Path to chip-cert executable	string	Yes
`--output`	Output path to store certificates	string	Yes
`--vendor_id`	Vendor Identification Number	integer or hex integer	Yes
`--product_id`	Product Identification Number	integer or hex integer	Yes
`--vendor_name`	Human-readable vendor name	string	Yes
`--product_name`	Human-readable product name	string	Yes
`--gen_cd`	Use this option to enable Certificate Declaration generation	boolean	No
`--cd_type`	Type of generated Certification Declaration: `0` - development, `1` - provisional, `2` - official	integer	No
`--device_type`	The primary device type implemented by the node	int	No
`--paa_cert`	Path to the Product Attestation Authority (PAA) certificate. Will be generated if not provided.	string	No
`--paa_key`	Path to the Product Attestation Authority (PAA) key. Will be generated if not provided.	string	No
`--valid_from`	The start date for the certificate's validity period.	string	No
`--lifetime`	The lifetime for the certificates, in whole days.	string	No

You can also run the following command to get more details on the parameters and their default value (if applicable):

python scripts/tools/nxp/generate_certs.py --help

Example of a command that will generate CD, PAA, PAI and DAC certificates and keys in both .pem and .der formats:

python scripts/tools/nxp/generate_certs.py --gen_cd --cd_type 1 --chip_cert_path ./out/chip-cert --vendor_id 0x1037 --product_id 0xA220 --vendor_name "NXP Semiconductors" --product_name all-clusters-app --device_type 65535 --output .

Note: the commands provided in this guide are just for the example and shall be adapted to your use case accordingly

c. Provisioning data

Generate new provisioning data and convert all the data to a binary (unencrypted data):

python3 ./scripts/tools/nxp/factory_data_generator/generate.py -i 10000 -s UXKLzwHdN3DZZLBaL2iVGhQi/OoQwIwJRQV4rpEalbA= -p 14014 -d 1000 --vid 0x1037 --pid 0xA220 --vendor_name "NXP Semiconductors" --product_name "Lighting app" --serial_num "12345678" --date "2023-01-01" --hw_version 1 --hw_version_str "1.0" --cert_declaration ./Chip-Test-CD-1037-A220.der --dac_cert ./Chip-DAC-NXP-1037-A220-Cert.der --dac_key ./Chip-DAC-NXP-1037-A220-Key.der --pai_cert ./Chip-PAI-NXP-1037-A220-Cert.der --spake2p_path ./out/spake2p --unique_id "00112233445566778899aabbccddeeff" --out ./factory_data.bin

Same example as above, but with an already generated verifier passed as input:

python3 ./scripts/tools/nxp/factory_data_generator/generate.py -i 10000 -s UXKLzwHdN3DZZLBaL2iVGhQi/OoQwIwJRQV4rpEalbA= -p 14014 -d 1000 --vid "0x1037" --pid "0xA220" --vendor_name "NXP Semiconductors" --product_name "Lighting app" --serial_num "12345678" --date "2023-01-01" --hw_version 1 --hw_version_str "1.0" --cert_declaration ./Chip-Test-CD-1037-A220.der --dac_cert ./Chip-DAC-NXP-1037-A220-Cert.der --dac_key ./Chip-DAC-NXP-1037-A220-Key.der --pai_cert ./Chip-PAI-NXP-1037-A220-Cert.der --spake2p_path ./out/spake2p --spake2p_verifier ivD5n3L2t5+zeFt6SjW7BhHRF30gFXWZVvvXgDxgCNcE+BGuTA5AUaVm3qDZBcMMKn1a6CakI4SxyPUnJr0CpJ4pwpr0DvpTlkQKqaRvkOQfAQ1XDyf55DuavM5KVGdDrg== --unique_id "00112233445566778899aabbccddeeff" --out ./factory_data.bin

Generate new provisioning data and convert all the data to a binary (encrypted data with the AES key). Add the following option to one of the above examples:

--aes128_key 2B7E151628AED2A6ABF7158809CF4F3C

Here is the interpretation of the required parameters:

-i                 -> SPAKE2+ iteration
-s                 -> SPAKE2+ salt (passed as base64 encoded string)
-p                 -> SPAKE2+ passcode
-d                 -> discriminator
--vid              -> Vendor ID
--pid              -> Product ID
--vendor_name      -> Vendor Name
--product_name     -> Product Name
--hw_version       -> Hardware Version as number
--hw_version_str   -> Hardware Version as string
--cert_declaration -> path to the Certification Declaration (der format) location
--dac_cert         -> path to the DAC (der format) location
--dac_key          -> path to the DAC key (der format) location
--pai_cert         -> path to the PAI (der format) location
--spake2p_path     -> path to the spake2p tool
--out              -> name of the binary that will be used for storing all the generated data

Here is the interpretation of the optional parameters:

--dac_key_password      -> Password to decode DAC key
--dac_key_use_sss_blob  -> Used when --dac_key contains a path to an encrypted blob, instead of the
                           actual DAC private key. The blob metadata size is 24, so the total length
                           of the resulting value is private key length (32) + 24 = 56. False by default.
--spake2p_verifier      -> SPAKE2+ verifier (passed as base64 encoded string). If this option is set,
                           all SPAKE2+ inputs will be encoded in the final binary. The spake2p tool
                           will not be used to generate a new verifier on the fly.
--aes128_key            -> 128 bits AES key used to encrypt the whole dataset. Please make sure
                           that the target application/board supports this feature: it has access to
                           the private key and implements a mechanism which can be used to decrypt
                           the factory data information.
--date                  -> Manufacturing Date (YYYY-MM-DD format)
--part_number           -> Part number as string
--product_url           -> Product URL as string
--product_label         -> Product label as string
--serial_num            -> Serial Number
--unique_id             -> Unique id used for rotating device id generation
--product_finish        -> Visible finish of the product
--product_primary_color -> Representative color of the visible parts of the product

3. Write provisioning data

For the K32W0x1 variants, the binary needs to be written in the internal flash at location 0x9D600 using DK6Programmer.exe:

DK6Programmer.exe -Y -V2 -s <COM_PORT> -P 1000000 -Y -p FLASH@0x9D600="factory_data.bin"

For K32W1 platform, the binary needs to be written in the internal flash at location given by __MATTER_FACTORY_DATA_START, using JLink:

loadfile factory_data.bin 0xf4000

where 0xf4000 is the value of __MATTER_FACTORY_DATA_START in the corresponding .map file (can be different if using a custom linker script).

For RW61X platform, the binary needs to be written in the internal flash at location given by __MATTER_FACTORY_DATA_START, using JLink:

loadfile factory_data.bin 0xBFFF000

where 0xBFFF000 is the value of __FACTORY_DATA_START in the corresponding .map file (can be different if using a custom linker script).

For the RT1060 and RT1170 platform, the binary needs to be written using MCUXpresso Flash Tool GUI at the address value corresponding to __FACTORY_DATA_START (the map file of the application should be checked to get the exact value).

4. Build app and usage

Use chip_with_factory_data=1 when compiling to enable factory data usage.

Run chip-tool with a new PAA:

./chip-tool pairing ble-thread 2 hex: $hex_value 14014 1000 --paa-trust-store-path /home/ubuntu/certs/paa

Here is the interpretation of the parameters:

--paa-trust-store-path -> path to the generated PAA (der format)

paa-trust-store-path must contain only the PAA certificate. Avoid placing other certificates in the same location as this may confuse chip-tool.

PAA certificate can be copied to the chip-tool machine using SCP for example.

This is needed for testing self-generated DACs, but likely not required for “true production” with production PAI issued DACs.

5. Useful information/Known issues

Implementation of manufacturing data provisioning has been validated using test certificates generated by OpenSSL 1.1.1l.

Also, demo DAC, PAI and PAA certificates needed in case chip_with_factory_data=1 is used can be found in ./scripts/tools/nxp/demo_generated_certs.

6. Increased security for DAC private key

6.1 K32W1

Supported platforms:

K32W1 - src/plaftorm/nxp/k32w/k32w1/FactoryDataProviderImpl.h

For platforms that have a secure subsystem (SSS), the DAC private key can be converted to an encrypted blob. This blob will overwrite the DAC private key in factory data and will be imported in the SSS at initialization, by the factory data provider instance.

The application will check at initialization whether the DAC private key has been converted or not and convert it if needed. However, the conversion process should be done at manufacturing time for security reasons.

There is no need for an extra binary.

Write factory data binary.
Build the application with chip_with_factory_data=1 set.
Write the application to the board and use it as usual.

Factory data should now contain a corresponding encrypted blob instead of the DAC private key.

If an encrypted blob of the DAC private key is already available (e.g. obtained previously, using other methods), then the conversion process shall be skipped. Instead, option --dac_key_use_sss_blob can be used in the factory data generation command:

python3 ./scripts/tools/nxp/factory_data_generator/generate.py -i 10000 -s UXKLzwHdN3DZZLBaL2iVGhQi/OoQwIwJRQV4rpEalbA= -p 14014 -d 1000 --vid "0x1037" --pid "0xA221" --vendor_name "NXP Semiconductors" --product_name "Lighting app" --serial_num "12345678" --date "2023-01-01" --hw_version 1 --hw_version_str "1.0" --cert_declaration ./Chip-Test-CD-1037-A221.der --dac_cert ./Chip-DAC-NXP-1037-A221-Cert.der --dac_key ./Chip-DAC-NXP-1037-A221-Key-encrypted-blob.bin --pai_cert ./Chip-PAI-NXP-1037-A221-Cert.der --spake2p_path ./out/spake2p --unique_id "00112233445566778899aabbccddeeff" --dac_key_use_sss_blob --out ./factory_data_with_blob.bin

Please note that --dac_key now points to a binary file that contains the encrypted blob.

The user can use the DAC private in plain text instead of using the SSS by adding the following gn argument chip_use_plain_dac_key=true.

6.2 RW61X

Supported platforms:

RW61X

there are three implementations for factory data protection

whole factory data protection with AES encryption ( chip_with_factory_data=1 chip_enable_secure_whole_factory_data=true ) examples/platform/nxp/rt/rw61x/factory_data/source/AppFactoryDataExample.cpp
src/platform/nxp/rt/rw61x/FactoryDataProviderEncImpl.cpp
only dac private key protection ( chip_with_factory_data=1 chip_enable_secure_dac_private_key_storage=true )
examples/platform/nxp/rt/rw61x/factory_data/source/AppFactoryDataExample.cpp

src/platform/nxp/rt/rw61x/FactoryDataProviderImpl.cpp
whole factory data protection with hard-coded AES key ( chip_with_factory_data=1 ) examples/platform/nxp/common/factory_data/source/AppFactoryDataDefaultImpl.cpp
src/platform/nxp/common/factory_data/FactoryDataProviderFwkImpl.cpp

for the first one, the whole factory data is encrypted by an AES-256 key, the AES key can be passed through serial link when in factory production mode, and will be provisioned into Edge Lock, and the returned AES Key blob (wrapped key) can be stored in the end of factory data region in TLV format. for the decryption process, the blob is retrieved and provisioned into Edge Lock and the whole factory data can be decrypted using the returned key index in Edge Lock. Compared with only dac private key protection solution, this solution can avoid tampering with the original factory data.

the factory data should be encrypted by an AES-256 key using “--aes256_key” option in “generate.py” script file.

it will check whether there is AES key blob in factory data region when in each initialization, if not, the default AES key is converted and the result is stored into flash, it run only once.

for the second one, it only protect the dac private key inside the factory data, the dac private key is retrieved and provisioned into Edge Lock, the returned key blob replace the previous dac private key, and also update the overall size and hash, and re-write the factory data. when device is doing matter commissioning, the blob is retrieved and provisioned into Edge Lock and the signing can be done using the returned key index in Edge Lock.

the factory data should be plain text for the first programming. it will check whether there is dac private key blob (base on the size of blob, should be 48) in factory data when in each initialization, if not, the dac private key is converted and the result is stored into flash, it run only once.

for the third one, it is a little similar to the first one, the whole factory data is encrypted by an AES key, but there are two differences:

the AES key is hard-coded and not provisioned into Edge Lock
the factory data should be encrypted by AES-128 key using “--aes128_key” option in “generate.py” script file.