Red Hat Bugzilla – Bug 1309779
openssl tools should not use SHA1 by default when generating digital signatures/certificates
Last modified: 2017-08-01 14:16:10 EDT
Description of problem: SHA1 was published in 1993 and is still in wide use today. However there are several weaknesses and the algorithms is considered today cryptographically broken (less effort than brute force is required). It is highly likely we will have collision attacks in the near future; i.e., forged certificates. For that it is recommended for our tools which deal with digital signatures to no longer use the SHA1 as a hash function by default. For maximum compatibility with old software we recommend the SHA2-256 algorithm to be used as the default replacement. As such, it is recommended for all of the included in openssl tools and shipped configuration files, to switch from SHA1 to SHA2-256 when generating certificates or digital signatures.
At least for certificates the default is SHA-256 already as configured in /etc/pki/tls/openssl.cnf in RHEL-7. Do you think that all the code should be patched to use SHA2-256 by default? I am not so sure about desirability of such change in released RHEL. I mean we should change configurations but hardcoded defaults in the code is a different beast.
So I've looked at the 1.0.1 and 1.0.2 difference and this would be solved nicely with the rebase as the hardcoded default hash changed from SHA-1 to SHA2-256 there.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHBA-2017:1929