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After openid_verify/2 has
redirected the browser to the OpenID server, and the OpenID
server did its magic, it redirects the browser back to this address. The
work is fairly trivial. If
cancel, the OpenId server denied. If
the OpenId server replied positive, but we must verify what the server
told us by checking the HMAC-SHA signature.
This call fails silently if their is no
field in the request.
openid(cancel) if request was cancelled by the OpenId
openid(signature_mismatch) if the HMAC signature check