Re: New function: consttime_memcmp(3)

[Alan Barrett <apb%cequrux.com@localhost>]

On Mon, 16 Mar 2015, Kamil Rytarowski wrote:
> I'm attaching a patch against current adding a new libc and 
> kernel function: consttime_memcmp(3). The code is borrowed from 
> OpenBSD timingsafe_memcmp(3) [1].

I haven't looked at the code, but what use case do you have that 
needs constant-time memcmp-like behaviour (with a three-state 
return: negative, zero, or positive), as opposed to the behaviour 
already provided by NetBSD's consttime_memequal(3) function (with 
a two-state return: non-zero or zero).

I also have an implementation of consttime_memcmp(), but 
I have found no use for it that cannot be satisfied by 
consttime_memequal().

--apb (Alan Barrett)