Abstract: Through analyzing a forward-secure signature and a forward-secure anonymous proxy signature in the literature，the thesis points out that the two forward-secure signatures are vulnerable to be attacked and gives two improvements on the basis of them.The improved schemes with the merits of the original schemes，are able to resist the attack of the attacker and satisfy the security requirements which the original schemes don’t satisfy，much better than the original schemes.

Key words: forward-security, digital signature, anonymous, proxy signature

摘要： 对文献中的一种前向安全的数字签名和一种前向安全的匿名代理签名进行了分析，指出了这两种签名方案容易受到伪造攻击，并在其基础上进行了改进。改进后的方案在具有原方案的优点的同时，能够抵抗攻击者的攻击，满足了原方案不满足的安全要求，大大优于原方案。

关键词: 前向安全, 数字签名, 匿名性, 代理签名