1. According to http://www.cs.technion.ac.il/users/wwwb/cgi-bin/tr-get.cgi/1996/CS/CS0885.ps.gz the only 112-bit secure 3DES mode is 3-ECB (others offer up to 75 bit effective key). 2. Looking at the commercial implementations in silicon, highest performance is achieved by pipelining, and therefore NOT by feedback across 3-ECB as a unit, but by using some of the inner-feedback weak modes. This is my speculation, based on publicly available docs. Would any insiders (Hi/Fn, LSI, Rainbow) offer opinion on 2. and deny or confirm that the highest performance mode uses outer-feedback on 3-ECB ?
