title: Re-install .cer Apple "Developer ID Installer" certificates from a backup
body: <p>Let's say an Apple developer program membership has expired, so new code signing certificates cannot be requested from the Apple site. Still I have a backup of:</p>
  <ul>
  <li><code>developerID_application.cer</code>, <code>developerID_installer.cer</code> (and the expiration date is <strong>2024</strong>, so it is still valid)</li>
  <li>a <code>CertificateSigningRequest.certSigningRequest</code> file from 2 years ago, that was created exactly at the same time than the .cer files</li>
  </ul>
  <p><strong>How to install these certificates on a new Mac installation, such that we can  use <code>productsign</code> to sign a .pkg installer with them?</strong></p>
  <p>Here is what I tried:</p>
  <ul>
  <li>Import the .cer files in the &quot;System&quot; Keychain, it seems successful</li>
  <li>Import the AppleWWDRCA.cer in the Keychain that I used at the creation time of these certificates (<a href="https://developer.apple.com/certificationauthority/AppleWWDRCA.cer" rel="nofollow noreferrer">https://developer.apple.com/certificationauthority/AppleWWDRCA.cer</a>), idem</li>
  <li><code>productsign --sign &quot;Developer ID Installer: MyName&quot; myinstaller.pkg myinstaller_signed.pkg</code></li>
  </ul>
  <p>Result:</p>
  <blockquote>
  <p>productsign: error: Could not find appropriate signing identity for &quot;Developer ID Installer: MyName&quot;</p>
  </blockquote>
  <p>I have looked at <a href="https://stackoverflow.com/questions/21244756/os-x-productsign-error-could-not-find-appropriate-signing-identity">OS X productsign error: Could not find appropriate signing identity</a> but it does not help here: I only have the 2 .cer files and the .certSigningRequest file. I don't have another Private key file. Also when I open the .certSigningRequest file, I see:</p>
  <blockquote>
  <p>Please specify the issuing Certificate Authority for MyName's certificate request<br />
  Issuing CA: Let me choose<br />
  What would you like to do?<br />
  Create a certificate for yourself<br />
  Create a CA<br />
  Use your CA to create a certificate for someone else<br />
  Request a certificate from an existing CA<br />
  Set the default CA<br />
  View and evaluate certificates</p>
  </blockquote>
  <p>What to do with this previous .certSigningRequest file?</p>