GitLab

It wrongly asserted that the key size equals the shared secret size,
when Authenticate() may also be called with a pinUvAuthToken, which can
be any multiple of 16 bytes in legth.

Also tighten up parsing of authenticator responses to ensure
pinUvAuthTokens are of a valid length for the chosen protocol version.

Bug: 1129946
Change-Id: I6d96307159d4e543e1a4f2bf7efa5e2ddefe7382
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2463236Reviewed-by: Adam Langley <agl@chromium.org>
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
Cr-Commit-Position: refs/heads/master@{#815708}