OpenSSL MD5 verification disabled?

Michael Catanzaro mcatanzaro at
Tue Mar 17 16:24:19 UTC 2015

Hi, I don't have any comment on the issue for your particular software
package, since I don't know how important the security of the TLS is for
that package and I'm not familiar with your compatibility needs.
However, I see the following lines in the patch:

// Work around ill-considered decision by Fedora to stop allowing
// certificates with MD5 signatures

It's not an ill-considered decision. Researchers first created a
certificate collision -- a fake cert that's valid for the MD5 signature
that a CA put on another cert -- in *2008*. You can't pretend these are
secure in 2015. If you want to accept MD5 certificates, which might make
sense depending on your compatibility needs, keep that in mind. It's
certainly better than no TLS at all, but won't stop a good attacker.

MD5 certificates were phased out years ago, and blocking them does not
cause any compatibility issues for certificates from real CAs anymore.
The logbook site should use SHA-256 instead of MD5. (Note that SHA-1 is
being phased out too!)


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