title: Is there any way to securely share credentials between whitelisted apps signed with different team ids on recent versions of iOS?
body: <ul>
  <li><strong>Keychain access groups</strong> and <strong>application groups</strong> are both segregated using the app's team id.</li>
  <li><strong>Named pasteboards</strong> are also sandboxed using the team id.</li>
  <li><strong>Kerberos SSO</strong> seems to work well, but opening the KDC to the internet is a security hazard so it can only really be used together with a VPN.</li>
  <li>The <strong>Shared Web Credentials</strong> API works well between native apps, but has intrusive popups showing up every time you attempt to access or even just check for the existence of credentials.</li>
  <li><strong>libdispatch</strong> can send messages to arbitrary apps, but the payload is limited to 64 bits and the recipient app must be currently running.</li>
  <li>No unique device identifier that could be used to derive a key for a cloud-based encrypted KVS can ever be shared between apps not on the same team id.</li>
  </ul>
  
  <p>…is there any way to share credentials (or any data, for that matter) between applications signed with different team ids, on recent versions of iOS? Apple doesn't allow migrating IAP, Passbook, etc to new team ids and it's blocking my team from implementing SSO between apps with historical team ids (M&amp;As, etc).</p>