GitHub custom action for GPG signing

DigiCert​​®​​ Software Trust Manager requires multifactor authentication. You will need to set up two credential types, namely an API token and an authentication certificate before you can access keypairs, certificates, and to sign code.

Create an API token

The API token is an authentication method used to verify the user and their permissions as set in DigiCert ONE®. The client authentication provides the first factor authentication.

To generate an API token:

Create an authentication certificate

The client authentication certificate is an authentication method used to verify the user and their permissions as set in DigiCert ONE. The client authentication certificate provides the second factor authentication.

To create a client authentication certificate:

Use secrets and secure files to ensure security and accountability among your GitHub users when they use DigiCert​​®​​ Software Trust Manager to sign code. The code examples later assume that you are using secrets and secure files.

GitHub Secrets

Secrets are variables in GitHub encrypted so users can input information without knowing what the value of that information is. For example, with API keys, you do not want all of your GitHub collaborators knowing what your unique API key is, but they may need to use it to use signing tools through DigiCert​​®​​ Software Trust Manager. You can set up a variable where "(api_key)" is the name and the value is the API key itself.

To add a certificate to GitHub secrets, you need to encode the certificate to a base64 string.

On Linux, run this command in Terminal:

base64 -i <file_name>

On Windows, run this command in PowerShell:

 $fileContentBytes = get-content 'YOURFILEPATH.pfx' -Encoding Byte 

 [System.Convert]::ToBase64String($fileContentBytes) 

The client tools need these environment variables to connect with DigiCert​​®​​ Software Trust Manager.

To integrate environment variables as GitHub secrets:

Commands to set environment variables

Once you save the variable, it is fully encrypted. Not even the creator of the value (you) can see the value. Make sure you save it elsewhere if it is something you will need in the future.

To set the API token as a new repository secret:

To set the client authentication certificate as a new repository secret:

To set the client authentication certificate password as a new repository secret:

To set up the certificate file for signing, run:

- name: Setup Certificate 

  run: | 

    echo "${{ secrets.SM_CLIENT_CERT_FILE_B64 }}" | base64 --decode > /d/Certificate_pkcs12.p12 

  shell: bash 

To set environment variables:

- name: Set variables 

  id: variables 

  run: | 

    echo "::set-output name=version::${GITHUB_REF#refs/tags/v}" 

    echo "SM_HOST=${{ secrets.SM_HOST }}" >> "$GITHUB_ENV" 

    echo "SM_API_KEY=${{ secrets.SM_API_KEY }}" >> "$GITHUB_ENV" 

    echo "SM_CLIENT_CERT_FILE=D:\\Certificate_pkcs12.p12" >> "$GITHUB_ENV" 

    echo "SM_CLIENT_CERT_PASSWORD=${{ secrets.SM_CLIENT_CERT_PASSWORD }}" >> "$GITHUB_ENV" 

    shell: bash 

Usage example

Copy and paste the following snippet into your .yml file.

- name: GPG signing with Software Trust Manager 

 
 

on: push 

 
 

jobs: 

  build: 

 
 

    strategy: 

 
 

      matrix: 

 
 

        os: [ubuntu-latest, windows-latest] 

 
 
 

    runs-on: ${{ matrix.os }} 

 
 

    steps: 

     - name: GPG signing with Secure Software Manager 

       uses: digicert/ssm-gpg-signing@latest-version 

 
 

    env: 

      SM_API_KEY: ${{secrets.SM_API_KEY}} 

      SM_CLIENT_CERT_PASSWORD: ${{secrets.SM_CLIENT_CERT_PASSWORD}} 

      SM_CLIENT_CERT_FILE: ${{secrets.SM_CLIENT_CERT_FILE}} 

The DigiCert​​®​​ Software Trust Manager client tools set up task installs and configures all the DigiCert​​®​​ Software Trust Manager client tools, including the CTL client and the SCD client.

To find the client tools installation path, run:

- run: echo “installation Path ${{ steps.SSMClientToolSetup.outputs.extractPath }}” 

During the task configuration step, there will be a prompt to input an API key, but you can skip this if you want to use the environment variables to add the API key.

To set the API key to GitHub secrets:

- name: GPG signing with Secure Software Manager    

  run: | 

     echo "SM_API_KEY=${{ secrets.SM_API_KEY }}" >> "$GITHUB_ENV"   

  env:  

    SM_API_KEY: ${{secrets.SM_API_KEY}}

Generate GPG master key using SMCTL

    - name: generate gpg master key using smctl 

        run: | 

           gpg keypair generate <master key alias> --key-alg “<algorithm>” --key-size        <RSA key size>|--curve “<ECDSA curve name>” --can-sign “<YES or NO>” --gpg-key-type “MASTER” --uids “name=<name>,email=<email>", “name=<name>,email=<email>" 

Download GPG keyring

     - name: Download GPG keyring 

       run: | 

           smctl gpg keyring download <gpg master key keypair id> <gpg master key          keypair id> 

To get a list GPG public and private keys, run:

   - name: List gpg public and private keys 

       run: | 

           gpg –list-keys <file path to keyring> 

          gpg --list-secret-keys <file path to keyring> 

To sign using the command line interface, run:

     - name: GPG signing 

       run: | 

           gpg --sign <unsigned file name> 

- name: 'build and release electron installer' 

on: 

  push: 

    tags: 

      - 'v*' 

       

jobs: 

  release: 

    runs-on: ${{ matrix.os }} 

     

    strategy: 

      matrix: 

        os: [windows-latest,ubuntu-latest] 

         

    steps: 

      - name: Check out Git repository 

        uses: actions/checkout@v2 

 

      - name: Install Node.js, NPM and Yarn 

        uses: actions/setup-node@v2 

        with:  

          node-version: 14 

         

      - name: Build/release Electron app 

        uses: samuelmeuli/action-electron-builder@v1 

        with:  

          github_token: ${{ secrets.github_token }} 

          release: ${{ startsWith(github.ref, 'refs/tags/v') }} 

          build_script_name: dist 

 

      - name: NuGet Install 

        uses: NuGet/setup-nuget@v1.0.5 

        with: 

          nuget-version: latest 

 

      - name: Setup Certificate 

        run: | 

          echo "${{secrets.SM_CLIENT_CERT_FILE_B64 }}" | base64 --decode > /d/Certificate_pkcs12.p12 

          cat /d/Certificate_pkcs12.p12 

        shell: bash 

 

           

      - name: Set variables 

        id: variables 

        run: | 

          echo "::set-output name=version::${GITHUB_REF#refs/tags/v}" 

          echo "SM_HOST=${{ secrets.SM_HOST }}" >> "$GITHUB_ENV" 

          echo "SM_API_KEY=${{ secrets.SM_API_KEY }}" >> "$GITHUB_ENV" 

          echo "SM_CLIENT_CERT_FILE=D:\\Certificate_pkcs12.p12" >> "$GITHUB_ENV" 

          echo "SM_CLIENT_CERT_PASSWORD=${{ secrets.SM_CLIENT_CERT_PASSWORD }}" >> "$GITHUB_ENV" 

          echo "C:\Program Files (x86)\Windows Kits\10\App Certification Kit" >> $GITHUB_PATH 

          echo "C:\Program Files (x86)\Microsoft SDKs\Windows\v10.0A\bin\NETFX 4.8 Tools" >> $GITHUB_PATH 

          echo "C:\Program Files\DigiCert\DigiCert One Signing Manager Tools" >> $GITHUB_PATH 

        shell: bash 

       

      - name: generate gpg master key using smctl 

        run: | 

           gpg keypair generate <master key alias> --key-alg “<algorithm>” --key-size        <RSA key size>|--curve “<ECDSA curve name>” --can-sign “<YES or NO>” --gpg-key-type “MASTER” --uids “name=<name>,email=<email>", “name=<name>,email=<email>" 

      

 

     - name: Download GPG keyring 

       run: | 

           smctl gpg keyring download <gpg master key keypair id> <gpg master key          keypair id> 

 

 

      

     - name: List gpg public and private keys 

       run: | 

           gpg –list-keys <file path to keyring> 

          gpg --list-secret-keys <file path to keyring> 

 

     - name: GPG signing 

       run: | 

           gpg --sign <unsigned file name 

Troubleshooting