中文摘要：

为了更全面分析前向门限秘密共享方案的安全性,针对石润华等人提出的公开可验证的前向门限秘密共享方案,通过理论分析和实验验证发现该方案存在2个安全漏洞：门限值k不可信;攻击者利用公开的秘密更新算法可破解出秘密值S.同时,针对一般前向门限秘密共享方案给出了新的分析方法.该方法通过扩展前向门限秘密共享方案的完备性和秘密更新算法的单向性,使分析后的方案具有更强的安全性.

英文摘要：

By means of theoretical analyzing and experimental verifying,two flaws in the public verifiable threshold proactive secret sharing scheme proposed by Shi Runhua,are found.First,the value of threshold k can not be trusted.Second,the attackers can crack the secrets S in terms of public shares update algorithm.At last,new analyzing methods for proactive secret sharing scheme are proposed,which can conduct comprehensive analysis of forward-threshold secret sharing scheme by extending the completeness of proactive secret sharing scheme,and the unidirection of shares updated algorithm.