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I have a RapidSSL certificate and the instructions asks me to include : RapidSSL SHA256 CA - G3, GeoTrust Global CA root and the Equifax Secure Certificate Authority root in my chain.

However, this creates all sorts of warnings in SSLLabs.com (SHA1withRSA - WEAK SIGNATURE) with the GeoTrust and Equifax root certs. I'm also seeing the warning "Intermediate certificate has a weak signature. Upgrade to SHA2 as soon as possible to avoid browser warnings".

Now if I remove the GeoTrust and Equifax certs from my chain (and just have my cert + RapidSSL SHA256 CA - G3), it fixes all those warnings and everything looks fine.

It also still displays the "GeoTrust Global CA" cert with the message in green "In trust store".

Am I going to have any SSL issues leaving out the GeoTrust and Equifax certs from my chain?

SSL Labs output (My cert + RapidSSL SHA256 CA - G3) :

Additional Certificates (if supplied)

Certificates provided 2 (2279 bytes)
Chain issues None
#2
Subject RapidSSL SHA256 CA - G3
Fingerprint: 0e34141846e7423d37f20dc0ab06c9bbd843dc24
Valid until Fri, 20 May 2022 21:39:32 UTC (expires in 6 years and 9 months)
Key RSA 2048 bits (e 65537)
Issuer GeoTrust Global CA
Signature algorithm SHA256withRSA


Certification Paths

Path #1: Trusted
1 Sent by server  www.example.com
Fingerprint: fbea1fc476bcee2eae7a1001e4a37bf560d0c013
RSA 2048 bits (e 65537) / SHA256withRSA

2 Sent by server  RapidSSL SHA256 CA - G3
Fingerprint: 0e34141846e7423d37f20dc0ab06c9bbd843dc24
RSA 2048 bits (e 65537) / SHA256withRSA

3 In trust store  GeoTrust Global CA   Self-signed
Fingerprint: de28f4a4ffe5b92fa3c503d1a349a7f9962a8212
RSA 2048 bits (e 65537) / SHA1withRSA
Weak or insecure signature, but no impact on root certificate
  • What is the actual chain leading to your certificate? Are those certs part of the chain? Generally speaking you should include all intermediate certs in the chain but never the root. Also, generally if the SSL Labs test has no complaints about missing certificates ("separate download" or something like that?) you probably serve all the certificates that you are supposed to. Can you add the necessary information (both what the actual chain looks like and what the SSL Labs test said) to the question? – Håkan Lindqvist Jul 24 '15 at 19:40
  • Done, please let me know if it's safe to leave it like that. Thanks. – Brian Smith Jul 24 '15 at 21:08
  • That looks good to me. What were those other certificates? Is the Geotrust cert that you mention de28f4a4ffe5b92fa3c503d1a349a7f9962a8212 or some other certificate? And the Equifax cert, is that something not listed in this chain at all? – Håkan Lindqvist Jul 24 '15 at 21:13
  • That fingerprint belongs to Geotrust Global CA. The Equifax is not listed unless I add it to my chain. Here is the output with everything added in to my cert (as per the instructions) : pastebin.com/9VN5DTYk – Brian Smith Jul 24 '15 at 21:27
  • Ok, so the Geotrust cert you talk about is then rather 7359755c6df9a0abc3060bce369564c8ec4542a3 and the Equifax cert is d23209ad23d314232174e40d7f9d62139786633a? – Håkan Lindqvist Jul 24 '15 at 21:29
4

This appears to be a case where CAs have done cross-signing.

There are two chains that end with your certificate:

Chain 1:

Path #1: Trusted  

1 Sent by server  www.example.com
Fingerprint: fbea1fc476bcee2eae7a1001e4a37bf560d0c013
 RSA 2048 bits (e 65537) / SHA256withRSA

2 Sent by server  RapidSSL SHA256 CA - G3
Fingerprint: 0e34141846e7423d37f20dc0ab06c9bbd843dc24
 RSA 2048 bits (e 65537) / SHA256withRSA    

3 In trust store  GeoTrust Global CA   Self-signed     
Fingerprint: de28f4a4ffe5b92fa3c503d1a349a7f9962a8212
 RSA 2048 bits (e 65537) / SHA1withRSA
Weak or insecure signature, but no impact on root certificate


Chain 2:

Path #2: Trusted  
1 Sent by server  www.example.com
Fingerprint: fbea1fc476bcee2eae7a1001e4a37bf560d0c013
 RSA 2048 bits (e 65537) / SHA256withRSA    

2 Sent by server  RapidSSL SHA256 CA - G3
Fingerprint: 0e34141846e7423d37f20dc0ab06c9bbd843dc24
 RSA 2048 bits (e 65537) / SHA256withRSA    

3 Sent by server  GeoTrust Global CA
Fingerprint: 7359755c6df9a0abc3060bce369564c8ec4542a3
 RSA 2048 bits (e 65537) / SHA1withRSA
WEAK SIGNATURE

4 In trust store  Equifax / Equifax Secure Certificate Authority   Self-signed 
Fingerprint: d23209ad23d314232174e40d7f9d62139786633a
RSA 1024 bits (e 65537)  / SHA1withRSA
WEAK KEY IN MOZILLA'S TRUST STORE   MORE INFO »
Weak or insecure signature, but no impact on root certificate

(from your SSL Labs report output)

Really, "Chain 1" is the primary option and "Chain 2" was probably of interest when this GeoTrust CA cert was first introduced and not everyone had the GeoTrust cert (de28f4a4ffe5b92fa3c503d1a349a7f9962a8212) in their lists, while they probably did all have the Equifax one (d23209ad23d314232174e40d7f9d62139786633a).


Both chains are technically still valid but the one starting at the Equifax root is showing its age. It has a 1024 bit root certificate (considered weak now) and the first intermediate cert is SHA1 signed (considered weak now).

I'd say, in this case there's probably little point serving intermediate certificates for "Chain 2".
If you want confirmation, wonder why they are still asking you to serve certificates for "Chain 2" or wonder what the compatibility concerns of not doing so may be, I would recommend that you ask your CA.

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