A method and system are provided for determining a shared secret between two entities in a cryptosystem. A first random secret is selected that is known to the first entity and unknown to the second entity. A first intermediate shared secret component is determined using the first random secret and a...http://www.google.com.tw/patents/US7221762?utm_source=gb-gplus-share專利 US7221762 - Authenticated ID-based cryptosystem with no key escrow
