Important note about SSL VPN compatibility for 20.0 MR1 with EoL SFOS versions and UTM9 OS. Learn more in the release notes.

Sophos Home v21 GA - Unable to upload internal CA

I am trying to upload/update a custom CA for SSL decryption (signing and validation), but it fails with the following message:
"Hochladen der Zertifizierungsstelle ist fehlgeschlagen. Ungültiger privater Schlüssel oder ungültiges Kennwort"
I know the passphrase for the key is correct, because it works if I upload it on the certificates page, just not on the ca page.

If I try to upload the certificate without the key the error is:
"Die Zertifizierungsstellen-Datei ist möglicherweise beschädigt"

I have compared the old and new crt file using this command on a linux workstation in my homelab:
diff -u <(openssl x509 -noout -text -in /tmp/old.pem) <(openssl x509 -noout -text -in /tmp/new.pem)

The only differences are the expected date, serial number and public key.

The article used: docs.sophos.com/.../index.html

Details to the certificate:
- Sub-CA of internal root CA

        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (4096 bit)

        X509v3 extensions:
            X509v3 Key Usage: critical
                Certificate Sign, CRL Sign
            X509v3 Extended Key Usage: critical
                OCSP Signing
            X509v3 Basic Constraints: critical
                CA:TRUE, pathlen:0

    Signature Algorithm: sha256WithRSAEncryption

Details of the private key:
- 4096 Bit
-RSA

What are the requirements for a ca certificate? Unfortunately the article is very thin here.



Added private key details.
[edited by: Herman Baum at 5:34 PM (GMT -8) on 7 Jan 2025]
Parents
  • Hello Herman,

    Your CA needs a private key for SSL decryption/re-encryption.

    The CA's public key is only good for certificate validation.

    Even if it is possible ... we never use a (sub-)CA of the internal CA. We always use the internal firewall SSL CA and distribute this CA as trusted in the LAN.


    Dirk

    Systema Gesellschaft für angewandte Datentechnik mbH  // Sophos Platinum Partner
    Sophos Solution Partner since 2003
    If a post solves your question, click the 'Verify Answer' link at this post.

  • Hello Dirk,

    thanks for the quick reply.

    I am of course also using a private key together with my certificate. It is a 4096bit RSA key.
    I have added that detail to the original question.

    Can you elaborate on why you never use and internal CA or sub CA and instead use the builtin one?
    Is it out of convenience or ease of use? Or maybe to keep the systems more separated?

Reply Children
  • We (and Certificate teams of customers) do not want to have an edge device that issues certificates on behalf of the internal CA.
    The additional effort required by a local firewall CA is minimal.


    Dirk

    Systema Gesellschaft für angewandte Datentechnik mbH  // Sophos Platinum Partner
    Sophos Solution Partner since 2003
    If a post solves your question, click the 'Verify Answer' link at this post.