I have somewhat mixed feelings regarding SHA1 support. On the one hand, it is useful in some cases to support legacy clients that "can't" upgrade. On the other

I have somewhat mixed feelings regarding SHA1 support. On the one hand, it is useful in some cases to support legacy clients that "can't" upgrade. On the other hand, I don't feel too bad about cutting off clients that are basically a blight on the internet - many of these applications have numerous security issues beyond weak crypto. As far as the CAs and browsers go, I would expect them to push back based on concern of not being able to enforce "you must support SHA256 and can only use SHA1 as a fallback". The browser vendors have the threat of scary SSL error screens, but people often click through those anyway, and habituating people to doing so is bad. Exceptions could be disabled, but that might just push more people to legacy browsers because they "work". I think this is gonna end up being one of those "pick the least bad solution" kind of things.