數位簽章在文件電子化以及電子商務漸漸普及後，由於具備簽署者不可以否認他所簽署過的電子文件(不可否認性)以及非簽署者無法偽冒簽署者簽署出一分合法的電子簽章(不可偽冒性)，因此在身分鑑別及確立法律責任的扮演著重要的角色。

　　數位簽章中的環簽章具有匿名性特性以及可以知道的確是從那群人之中所簽署出來的簽章，而且具備了不需要初始的步驟也不需要和群體中的其他成員合作即可簽署出代表那群體的簽章的特性。由於環簽章的完全匿名特性，在某些情況可能不大恰當，因此本論文提出了指定識別式環簽章，即對於某些特定人來說他可以知道環簽章的簽署者是誰，但是此人卻又不能證明給其他人知道誰是真正簽署者，因此對於其他人而言這個環簽章還是跟一般的環簽章沒有不同。

　　另一方面本論文同時也提出了離線可信任第三者可追蹤之指定識別式環簽章，與前者之不同在於多了離線可信任第三者可以追蹤出誰是真正的環簽章簽簽署者。

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