中文摘要：

签名只有接受者才能验证,而任何第三方只有在接受者的合作下才能验证签名的数字签名方案称之为有向签名.而在大多情况下,有向签名通常是一个人,然而当所需签名的消息代表一个群体时,就需要群体中的一部分人同意,门限签名方案就被用作解决这个问题.由于在许多特定的应用环境下,一个可被所有成员信任的可信中心并不存在,所以不需要可信中心的门限签名方案就显得很有吸引力.文章提供了一个安全有效的有向门限签名方案.

英文摘要：

The signature on the message should be such as only the signature receiver can verify the signature and prove the validity of the signature to any third party. Nobody can check the validity of signature without his cooperation. In most situations, the signer is generally a single person. However when the message is on behalf of an organization, a valid message may require the approval or consent of several people. Threshold signature is an answer to this problem. Generally speaking, as an authority which can be trusted by all members doesn＇t exist, a threshold signature scheme without a trusted party appears more attractive. This paper proposed a directed threshold signature scheme.