tree 82798ee304a4b73ef7e822298f86ee8d536d920a
parent 10f16912818103ef9d12a774cdabb434c66e3236
author Mike Burrows <m3b@google.com> 1438893258 -0700
committer Mike Burrows <m3b@google.com> 1438893258 -0700

v.io/syncbase/x/ref/services/syncbase/signing: Add signing mechanism to allow for syncbase updates to be signed.

This chaange adds mechanisms to allow syncbase to sign the upadtes
made by its clients so that when these updates are received by other
syncgroup members, the signatures can be checked.

The primary interface is in
        v.io/syncbase/x/ref/services/syncbase/signing

It is significantly more complicated than one might wish.  See the
comment at the top of signing/signing.go for the rationale.
Suggestions on how to relieve the various issues in simpler ways
would be welcome.

Suggested reviewing order:

Read the comment at the top of signing/signing.go for an overview.
Then bottom up:

  signing/krl
  - a placeholder key revocation list.  I added this just so if we
    ever get such a thing, we know where the calls will go.

  signing/hashcache
  - a simple cache for data that can be reused across signatures

  signing
  - The primary interface that signs and checks data.  The test
    contains various benchmarks, and shows how the interface is
    expected to be used by the various participating syncbase
    servers.

  - the validationcache.go module uses signing/hashcache to cache particular
    types of data.  Performs all the marshalling and hashing that would
    otherwise be repeated per signature.  It's in the same package as
    signing.go because the two share types.

Change-Id: I4a830b4811ffa63cb9391261a2c35fd77da60ba6