'Data is a structure with a reference to an already added key object and
some data that the clients wants signed with that key.  If the key
object wasn\'t loaded, return AGENT_FAILURE, else return the signature.'

def agentc_SIGN_REQUEST(self, data):

    (blob, data) = getNS(data)
    if (blob not in self.factory.keys):
        return self.sendResponse(AGENT_FAILURE, '')
    (signData, data) = getNS(data)
    assert (data == '\x00\x00\x00\x00')
    self.sendResponse(AGENT_SIGN_RESPONSE, NS(self.factory.keys[blob][0].sign(signData)))
