[FIXED] Cannot install packages error: rpmts_HdrFromFdno: Header V3 DSA/SHA1 Signature, key ID 6b8d79e6: BAD

Sorry for posting it in a bugtrack. but server cannot work as it is. When I'm trying to update ANY package via "yum update" I'm getting "Header V3 DSA/SHA1 Signature BAD" error. Is there a way to fix this or do I have reinstall entire system from scratch again? What is the problem and why this has hapenned?

Example of the error output after yum update package look like this::

================
..........
Total size: 238 k
Installed size: 776 k
Downloading Packages:
error: rpmts_HdrFromFdno: Header V3 DSA/SHA1 Signature, key ID 6b8d79e6: BAD

Problem opening package php-mcrypt-5.3.3-1.el6.rf.x86_64.rpm
.. install failed!
================
Could that be due to self-signed SSL certificates?
How is this fixable?
Many thanks for your time.