Certificate Issues

guardian

Did 2.3 Default to sign certificates with MD5?

I'm getting a warning from the new version of OpenVPN Connect for android about TLS certificate signed with MD5.

How can I display all my certificates to see what is going on? The certificate manager doesn't seem to show any details.

I started the process of recreating another certificate just to see what signing algo is used and it seems to default to SHA256.

How can I troubleshoot… I have CA, Intermediate CA, Server Cert, User Certs... I'd like to know for sure if the problem goes all the way back to the CA, or if it's just a server cert.

or is it the TLS Key in the cryptographic settings (# 2048 bit OpenVPN static key) that was generated automatically.

Any advice/assistance is much appreciated.

viragomann

@guardian:

Did 2.3 Default to sign certificates with MD5?

I'm in doubt.

In the cert manager you can find an i(nfo) symbol beside each cert. After a click on it you can see the signature digest.

guardian

@viragomann:

@guardian:

Did 2.3 Default to sign certificates with MD5?

I'm in doubt.

In the cert manager you can find an i(nfo) symbol beside each cert. After a click on it you can see the signature digest.

Thanks for the hint. I see why you are in doubt.

So am I, but OpenVPN Connect (v1.1.26-Build 95 Dec 12, 2017) running on on Android 5.1.1 gave me the following message:

Warning!
TLS: received certificate signed
with MD5. Please inform your
admin to upgrade to stronger
algorithm. Support for MD5 will be
dropped the end of Apr 2018
I wasn't able to check the automatically generated TLS certificate, but when I checked each of the user certs the relevant info was:

Signature Digest: RSA-SHA512
EKU: TLS Web Client Authentication

There is no (i) for the CA, so I don't know exactly what is going on, but after a quick search I found an openssl command to try.

I the CA/Intermediate CA into stdio for openssl x509 -noout -text and got the following output:

Primary CA

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 0 (0x0)
    Signature Algorithm: sha512WithRSAEncryption
        Issuer: [REDACTED]
        Validity
            Not Before: May  5 07:15:26 2017 GMT
            Not After : May  3 07:15:26 2027 GMT
        Subject:  [REDACTED]
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (8192 bit)
                Modulus:
                       [REDACTED]
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Subject Key Identifier: 
                 [REDACTED - 20 Bytes - 40hex digits]
            X509v3 Authority Key Identifier: 
                keyid:[REDACTED - 20 Bytes - 40hex digits]
                DirName:[REDACTED]
                serial:00

            X509v3 Basic Constraints: 
                CA:TRUE
            X509v3 Key Usage: 
                Certificate Sign, CRL Sign
    Signature Algorithm: sha512WithRSAEncryption
                [REDACTED - 20 Bytes - 40hex digits]

Intermediate CA

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 3 (0x3)
    Signature Algorithm: sha512WithRSAEncryption
        Issuer: [REDACTED]
        Validity
            Not Before: May  5 07:25:42 2017 GMT
            Not After : May  3 07:25:42 2027 GMT
        Subject: [REDACTED]
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (4096 bit)
                Modulus:
                [REDACTED]
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Subject Key Identifier: 
                 [REDACTED - 20 Bytes - 40hex digits]
            X509v3 Authority Key Identifier: 
                keyid: [REDACTED - 20 Bytes - 40hex digits]
                DirName:[REDACTED]
                serial:00

            X509v3 Basic Constraints: 
                CA:TRUE
            X509v3 Key Usage: 
                Certificate Sign, CRL Sign
    Signature Algorithm: sha512WithRSAEncryption
               [REDACTED]

The Key Identifiers are 160bits long, and the signature algo was shs512, which is a far cry from MD5!

I looked in the OpenVPN Connect log (can't copy/paste or otherwise copy it) and I see two certificates being verified (and they indicate they are signed using RSA/SHA512 (4096 bits)).

Then I get the following lines: (Transcribed manually)

SSL Handshake TLSv1.2/TLS-ECDHE-RSA-WITH-AES256-GCM-SHA384
Session is ACTIVE
EVENT: WARN info 'TLS: received certificate signed with MD5. Please inform your…

From the log, the server key and user keys are both RSA/SHA512 (4096 bits)), so the problem is either the 2048 bit automatically generated TLS key (which I don't know how to check), the android app or something else I haven't thought of.

Any suggestions? Have I found an OpenVPN bug, an android problem or what?

guardian

The problem must have been with the android client. There was an update awhile back, and I just thought to check, and the problem is gone.

nicolamersi

I have the same problem with openvpn connect 1.1.27 on android and openvpn 1.2.9 0 (iOS 64-bit) both latest versions.
I cannot understand what is md5 signed but I am worried april is round the corner.

openvpn.png_thumb

nicolamersi

I still cannot figure if it is a mistake of the cli version or if my openvpn connection is going to stop working

viragomann

I'm also using OpenVPN Connect 1.2.9 build 0 (iOS 64-bit) and there's no problem like that.