Phil Zimmermann gave it a stab:<p><a href="https:&#x2F;&#x2F;github.com&#x2F;SilentCircle&#x2F;contact-discovery" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;SilentCircle&#x2F;contact-discovery</a><p>I suggested this to Moxie, he said &quot;it&#x27;s not meaningfully privacy preserving&quot;, but there wasn&#x27;t any more detail.