Legacy option for key length?

[David Newall]

On 01/01/18 04:58, Emmanuel Deloget wrote:
> The idea of removing weak ciphers from a widely used piece of software is
> a good one - that way, you strengthen the whole ecosystem. Going the
> reverse path would simply make less informed people be the weak link of the
> Internet, putting possibly many more at risk.

This doesn't make the Internet more secure because people aren't about 
to throw away expensive equipment just because the latest openssh throws 
a hissy fit.  They'll use an alternative.  Perhaps the alternative will 
be an older, less secure version of openssh. Perhaps it will be even 
less secure telnet.  They will continue to use their still-good 
equipment, and so they should.

If people choose to use old versions of openssh, which is likely, they 
may also choose to make that the only version they use.  It makes a lot 
of sense: it saves having to think about two different versions of the 
same software, one which works properly and one which seems broken.  
Force people to make this choice and you weaken the whole ecosystem.

Is there a way to stop people using weak ciphers without weakening the 
ecosystem?  There is a way which is close: make openssh not use weak 
ciphers unless the user says "I really, really need to use this weak 
cipher."  That's all this is about. That doesn't weaken the ecosystem; 
it makes it stronger.

Removing a weak cipher weakens the ecosystem by pushing people into 
using old tools that have real bugs.  It's also arrogant.  it sounds too 
much like, "you're too ignorant/lazy/cheap to decide what's right for 
you so we'll make you do what we want, and we don't care how expensive 
and disruptive it is for you."

Removing a weak cipher breaks things that it didn't need to break.  
That's outrageous.

It does not hurt to make the weaker cipher an option.  It's not hard, no 
harder than the effort to remove it.