Re: Is there a hidden channel in X authentication?

[daw () mozart cs berkeley edu (David Wagner)]

Michael Wojcik  wrote:
> In any case, it's easy enough to mask the time by using a hand-coded
> comparison loop that always compares all the bytes and sets a flag if any of
> them differ.

A nice approach is to do what Unix password authentication does:
Hash both inputs, and then check if the hashes are the same.  The latter
comparison can be done with memcmp(), because the timing side-channel
reveals nothing if the hash is one-way.