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Attestation keys are keypairs. The private keys are used by Smart ID Mobile App and Smart ID Desktop App to sign Certification Signing Requests (CSR) while the public keys are used by Smart ID Identity Manager to verify the requests.

As the default, built-in attestation keys can be found in any Smart ID Mobile App and Smart ID Desktop App installation. Any , any device can install the app and try to request certificates. Configuring custom keypairs limits the devices that can request certificates to devices whose mobile or desktop app has the custom private key installed. The corresponding public keys can be configured into Identity Manager. This process consists of two steps:

1. Generate the PKCS#12 keystores.
   To make the public keys available to Identity Manager, keystores that contain a certificate with the public key must be created. Nexus provide a tool that, given the modulus and public exponent of the public key in BASE64 Base64 format (or an RSA JWK public key), creates the keystore.

2. Configure the sign and encrypt engine.
   The sign and encrypt engine must have access to the keystores.

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Before you proceed with the configuration in IDMIdentity Manager, make sure that:

• You have a mobile and/or desktop app with custom keys.

• You have the public key material of these custom keys. That is, a string that looks similar to this, containing the public key in single-line JWK-based format ({"alg":"RS256", ...etc... ,"use":"sig"}):

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• You have the Nexus keystore creator tool.

• You have a JRE installed.

Step-by-step instructions

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1. Keep the public key material at hand. For our example, this
   This example will use the following:

   Code Block

   PublicKey: {"alg":"RS256","e":"AQAB","keystate":"active","kid":"attestation_2023-11-02T08:29:08GMT","kty":"RSA","n":"trfHQvFlcFcOEaB9v9tF6R1NggU3o9ddhmDb3GnGuEA3bP8XaKOgIrvh-KFvinE0xATcZk_XQC9n5ORhm-c5KvfryAdCGM62SKoBonc7Av7Iu6YHdcJHjoSCvjNSsw6B3mPoWP6IRvzwZRKgLHIDeNCjA7r0oKCXQIr05IxMVjOSHD8FIxKsgDq8CaF6j-0UFYS92pV5Ok-20nXqLsGv_IHojqazIE3xnNi1kEmNJF4q2LmVFu6VFkegjCj_O78wIGTI9JUZJK1LNMU1BqSDUKek8iTGPgojurNLe31l4Uvpe4j1Gi52mVzEiCufKhJP4xJzK7EGeT9rtcuUf4tB5SmCT_t9WYz6MvJ7cwFJ9sF7bb8vwYU22qgKuyvGtQGIojoYXOyWzCj3E3ZJM_PQxOyJwRF8oCGYD1UjHGdDqzFVQa3NHKwTlz4vdnfRzAdcbG3tn0tB5OCA8vMrGZvP30QJx0MmBrxduLm4bN59FSPV1WLmFkYOVVdf0RIG-bNq65rrlMOOQcV5jasgBEy6alb5uh21ewWx0Ld2DOMosWCEDa6G02QRLZfWIAqMvRvZtfyrv5FRIVoAPUQTnFMH7AGNAQ0rEywYPRa0XE7viTspeLULRrltjzh5rg9YXVhNspyca4SqooZniVEDz2cqOSn7r37VXD_qz2DBKPtSXo8","n#len":"4096","storage":"APP","use":"sig"}

2. If you are on a Windows machine and the environment variable JAVA_HOME is not set, edit createP12.bat and createP12fromJWK.bat and set JAVA_HOME to point to your java Java installation.

3. Start the keystore creator tool.
   You can either start it in a mode that expects a complete public key in JWK format(createP12fromJWK.bat / createP12fromJWK.sh), or in a mode that expectsindividual key components (createP12.bat / createP12.sh):

   1. Start the keystore creator by executing createP12fromJWK.bat (on Windows) or createP12fromJWK.sh (on Linux). Then follow the instructions on the screen:

      1. Enter the public key in single-line JWK formatJWK format.

      2. Enter the filename file name of the keystore to create, for example,"attestationKey.p12".

      3. Enter the keystore's password. You need to enter this twice for verification. Write this password down or remember it, as you will need to also set in the sign and encrypt engine's configuration. The tool will now create a dummy certificate with the given public key. The certificate itself is not relevant, it just serves as a container for the public key. The path to the created file will be printed on the screen.If the file could not be created, for example, because of missing write permissions, the tool will print its contents on the screen, as a long BASE 64 string. You can copy and paste this string in a file, Base64-decode it and store it. This will create exactly the same file that could not be created in the previous step. Alternatively, fix the problem and rerun the tool.

   2. Start the keystore creator by executing createP12.bat (on Windows) or createP12.sh (on Linux). Then follow the instructions on the screen:

      1. Enter the public key exponent.
         This is denoted "e" in the key material. In our example, that would be "AQAB". As a matter of fact, it is highly likely that your key also has a public key exponent of the example above it is "AQAB".

      2. Enter the modulus.
         This is denoted "n". In this example, this would be the example above it is the long string: "trfHQ....tSXo8".

      3. Enter the filename file name of the keystore to create, for example, "attestationKey.p12".

      4. Enter the keystore's password. You need to enter this twice for verification. Write this password down or remember it, as you will need to also set

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Configure the sign and encrypt engine

The keystore must be available to both Identity Manager AdministratorAdmin, for configuring processes with the created attestation keys, and Identity Manager Operator.

Do the following:

1. Copy the created keystore to a location where Identity Manager can access it.

2. Edit the sign and encrypt engine's configuration and create a new key entry referencing the keystore.

3. Create a new descriptor entry referencing this key entry. The name of the descriptor must be exactly the same as it is named in the Smart ID mobile /desktop app and Smart ID Desktop App, prepended with the string "att_".
   The key name is denoted "kid" in the key material, so in . In the example above you need to set it to "att_attestation_key_id" , it is "attestation_2023-11-02T08:29:08GMT”, so the descriptor name would be “att_attestation_2023-11-02T08:29:08GMT“.

To use new keys for an existing descriptor, create a new descriptor or key entry with an incremented version. Signatures will be validated against all versions of the key, until a valid one is found. This is useful in case some clients still have the old keys.

Sample descriptor configuration

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<?xml version="1.0" encoding="UTF-8"?>
<engineSignEncrypt>
    <descriptors>
         <descriptor name="att_attestation_key_idattestationKeyId" version="1">
            <type algorithm="SHA256withRSA" size="" result="" key="attestationKey_old" />
        </descriptor>
          <descriptor name="att_attestation_key_idattestationKeyId" version="2">
            <type algorithm="SHA256withRSA" size="" result="" key="attestationKey_current" />
        </descriptor>
        <!-- others descriptors -->
    </descriptors>
    <keys>
        <key name="attestationKey_old">
            <type name="pkcs12" locationValue="classpath:attKeyOld.p12" pin="1234"/>
        </key>
         <key name="attestationKey_current">
            <type name="pkcs12" locationValue="classpath:attKeyCurrent.p12" pin="1234"/>
        </key>
        <!-- others keys -->
     </keys>
</engineSignEncrypt>