On 2 Jan 2009, at 12:33, Joe Greco wrote:
We cannot continue to justify security failure on the basis that a significant percentage of the clients don't support it, or are broken in their support. That's an argument for fixing the clients.
At a more basic level, though, isn't failure guaranteed for these kind of clients (web browsers) so long as users are conditioned to click OK/ Continue for every SSL certificate failure that is reported to them? If I was attempting a large-scale man-in-the-middle attack, perhaps I'd be happier to do no work and intercept 5% of sessions (those who click OK on a certificate that is clearly bogus) than I would to do an enormous amount of work and intercept 100% (those who would see no warnings). And surely 5% is a massive under-estimate. Joe