在數位化的時代，資訊是非常容易遭到複製以及發生偽造或欺騙的情形，因此須要有一套機制來解決此類爭議。目前大多利用數位簽章技術對數位化資料進行認可與保證。

　　傳統數位簽章中，只有簽章者本身能夠產生有效之數位簽章。某些情況下，簽章者無法親自產生數位簽章，須交由代理人簽署，代理簽章技術因而產生。原始的代理簽章都是原始簽署者授權給一個代理人來代理簽署文件，然而，當原始簽章者是一個十分重要的人物，為了防止代理權被濫用，原始簽章者可能不願意只將代理權力賦予單一個代理人。基於上述的考量，多代理人之代理簽章技術因而產生。在現實環境中，一家公司的主管可能要將簽章簽署權力授予下屬，但是，為了避免簽署權力遭濫用及符合分層負責之原則，主管可選擇特定代理人群體代理簽署。但是綜觀現今之多代理人之代理簽章，並無法解決上述之問題。

　　本論文著眼於上述之問題，因此，提出了一種新型態的多代理人之代理簽章，稱之為『可選擇代理群之代理簽章』。可選擇代理群之代理簽章是指，原始簽章者可將簽署簽章之權力授予一代理人群體，在此代理人群體中，可依簽署權力細分為代理人子群，每一代理人子群皆可產生有效之代理簽章。

　　除此之外，本論文亦將可選擇代理群之代理簽章所使用之金鑰管理概念加以延伸，提出了一般化之門檻值簽章與一般化門檻值之密碼系統概念，以期擴大應用之範圍。

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