[openssl-users] troubleshooting a puzzling issue

Viktor Dukhovni openssl-users at dukhovni.org
Fri Jan 13 15:47:34 UTC 2017

On Fri, Jan 13, 2017 at 04:17:14PM +0100, Thierry Parmentelat wrote:

> Thanks Viktor for your feedback
> Well, the 2 certificates are embedded in the python code as PEM; I am
> attaching them again here as plain files if that helps

The leaf certificate is signed with RSA+MD5:

    $ openssl x509 -in /tmp/p1 -noout -text | egrep -v '^ *..:'
	    Version: 3 (0x2)
	    Serial Number: 3 (0x3)
	Signature Algorithm: md5WithRSAEncryption
	    Issuer: CN=onelab.inria
		Not Before: Aug 18 13:30:49 2014 GMT
		Not After : Aug 17 13:30:49 2019 GMT
	    Subject: CN=onelab.inria.thierry_parmentelat
	    Subject Public Key Info:
		Public Key Algorithm: rsaEncryption
		    Public-Key: (1024 bit)
		    Exponent: 35 (0x23)
	    X509v3 extensions:
		X509v3 Basic Constraints: critical
		X509v3 Subject Alternative Name:
		    URI:urn:publicid:IDN+onelab:inria+user+thierry_parmentelat, URI:urn:uuid:8ee5aabe-5a16-4ac5-a18f-7ca145af285a
	Signature Algorithm: md5WithRSAEncryption

> In terms of versioning, on one box that exhibits the issue of returning -1, I have this:
> # cat /etc/fedora-release
> Fedora release 24 (Twenty Four)

Redhat is removing support for MD5 signatures from their OpenSSL
builds.  From a recent email from them to the OpenSSL team:

    We (Red Hat Enterprise Linux developers) decided to disable
    support for verification of signatures with MD4, MD5, and SHA0
    hashes in openssl library in Red Hat Enterprise Linux 6 and
    newer and in Fedora. ...

Your 5 year MD5 certificate is getting stale, time to use something
a bit more current.  Also its rather small exponent (35) is very
unwise.  While not quite as bad as 3, it may be open to attack.


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