A digital signature is a data digest encrypted with the private key of the signer. 数字签名是指使用签名人私钥加密的数据摘要。
One can forge an effective proxy signature that will be accepted by the signature verifier and that will not identify the true signer to management. 该攻击能够伪造出有效的代理签名，使签名验证人可以接受该代理签名，但管理中心并不能通过此签名来辨认出代理签名人的身份。
