Proposal to modify the Russian standard for electronic digital signature in order to eliminate the broadband covert channel

Most digital signature algorithms have the ability to organize hidden channels for transmitting information. Their presence was revealed after the publication of a digital signature scheme based on the El-Gamal cipher. The bandwidth of these channels ranges from a few bits (narrowband channels) to 256-512 bits (broadband channels). The literature describes several ways to eliminate broadband channels with the help of a supervisor. The analysis of existing methods of elimination of hidden channels in digital signature algorithms is given. The shortcomings of the existing schemes are revealed. A method of modification of the Russian standard of electronic digital signature GOST R 34.10-2012 has been developed in order to eliminate the broadband hidden channel. The method provides for the presence of a supervisor who does not participate in the formation of the signature and can check signed messages for the absence of hidden channels.