I host a website that uses mTLS for authentication. I created a client cert and installed it in Firefox on Linux, and when I visit the site for the first time, Firefox asks me to choose my cert and then I’m able to visit the site (and every subsequent visit to the site is successful without having to select the cert each time). This is all good.

But when I install that client cert into GrapheneOS (settings -> encryption & credentials -> install a certificate -> vpn & app user certificate), no browser app seems to recognize that it exists at all. Visiting the website from Vanadium, Fennec, or Mull browsers all return “ERR_BAD_SSL_CLIENT_AUTH_CERT” errors.

Does anyone have experience successfully using an mTLS cert in GrapheneOS?

[SOLVED] Thanks for the solution, @[email protected]

  • @[email protected]English
    4•4 months ago

    After some searching, maybe following the instructions on this blog post would work?

    I’m by no means an expert though, so take my suggestions with a grain of salt.

    • @one_knight_scriptingEnglish
      6•4 months ago

      I’m by no means an expert though, so take my suggestions with a grain of salt.

      Good on you for trying to help though, seriously. And OP I wanna hear if you’re able to get it squared away.

    • Mike WooskeyOPEnglish
      2•4 months ago

      Thanks for your research and the suggestion, @[email protected].

      I wasn’t able to make that work, but I don’t think it was trying to solve the problem I’m having, anyway. That procedure was to add self signed SSL certificate to Android, but my certificate is neither self-signed nor an SSL cert. At least I think not - I find certs very confusing. The cert I’m trying to work with is an mTLS cert, a client cert. It’s not used to establish a secure SSL connections, it’s used to verify that I (the person with the cert) and authorized to use the app.

      Additionally, I’m able to successfully install the cert into Android, but the problem is that it seems to be ignored. The mTLS cert is installed in GrapheneOS’s “VPN & App User Certificate” section, and my CA cert is installed in the “CA Certificate” section. Vanadium, Fennec, and Mull browsers just aren’t using them. :(

      • @[email protected]English
        2•4 months ago

        Like I said, not an expert haha (thanks for explaining what mTLS is because I had assumed I knew but truly didn’t)

        That being said, I found a reddit thread detailing what seems to be the same issue as you, with OP linking a Stack Exchange post with their solution.

        • Mike WooskeyOPEnglish
          3•4 months ago

          [SOLVED!] That Stack Exchange post was the solution! I had to ask ChatGPT for assistance (e.g., “how do I view the contents of a .crt and a .p12?”, “how do I add a CA to a client cert?”), but it worked. Thanks for your help, @[email protected].

          I don’t think I would have ever thought that my client cert didn’t contain the CA, especially because when I clicked on the client cert that was installed in GrapheneOS, it showed me a summary that said it did contain a CA! grrrr

          (tagging @[email protected] as he wanted to know the solution)