自我認證之多文件門檻式簽密機制－以國軍電子公文系統為例

Self-Certified and Threshold Multi-Document Mechanism of Signature Schemes-A Case Study of Military E-Document

黃國維(Kuo-Wei Huang) ； 蕭柏薰(Po-Hsun Hsiao) ； 呂俊成(Ji-Cheng Liu) ； 蘇品長(Pin-Chang Su)

《國防管理學報》 34卷2期 (2013/11) Pp. 1-18

摘要

「國軍電子公文系統」為國軍各單位或與政府各機關團體彼此間，依照行政院所頒佈之公文程序條例所撰擬的文書，並將所產製文件透過資訊系統及網際網路相互傳遞，主要用於處理涉及政策、制度、督導、考核、管理及執行之策劃與落實。鑑於網路與密碼技術趨於成熟，資安防護機制相關研究已受到重視，故如何運用安全的機密機制導入國軍電子公文系統，減低洩密情事，值得探究。現今的加密作業大多採用一份文件執行一次加密的方式，惟當文件數目數以萬計時，將導致運算繁複與時間耗費，為提供國軍作為未來電子公文系統規劃之參考範疇，本研究利用橢圓曲線密碼系統快速運算的特點，提出多重公文一次簽密之應用方法，在相同的密鑰長度下，其運算速度將比現行RSA、ElGamal演算法更加快速，並減少公文的簽密次數，達到提升效率、縮短作業時間與增加安全性的效益。此外亦結合了（t, n）門檻式加密機制，使其密文具有門檻的特性，當解密者人數未達到門檻值時則無法解開密文，可防止有心人惡意竊取與監守自盜的情事發生。另本研究同時設計自我認證機制，使得完成註冊程序的通訊雙方能在不依賴第三方認證中心的條件下，利用公鑰及簽章等參數資訊相互進行認證，將能更有效率的縮短作業時間，並防止憑證中心的偽冒攻擊。

關鍵字

自我認證 ； 橢圓曲線 ； 多文件 ； 門檻式 ； 簽密機制

並列摘要

Military e-document system of Military units follows the documents procedure ordinance of the Executive Yuan to produce electronic official documents and to exchange between government agencies and organizations through information management systems on the Internet. The e-document system is mainly used for processing, planning, and implementation of policies, supervision, assessment, management and execution. Owning to maturing Internet network and cryptographic technologies, information security studies have been emphasized. Therefore, it is worth studying to apply secure and confidential mechanisms to reduce divulgation in military e-document system. Though numbers of one-time encrypted documents will result in complicated computing and time-consuming, the study proposed a new mechanism for planning future electronic document system. The study applied elliptic curve cryptography technique to speed up computation for one-time signature multiple documents. Under the same length of encrypted key, the computation time will faster than the current RSA and ElGamal algorithms. The signcryption times and operation period will be promoted. The proposed scheme will be more secure and efficient. In addition to (t, n) threshold signcryption mechanism, the scheme also has ciphertext threshold characteristics. The document cannot be decrypted without reaching the threshold of decrypting numbers, and then the ciphertext malicious theft and embezzlement occurrences can be prevented. Furthermore, the study proposed self-certified mechanisms to use public key and signature to complete cross authentication procedures without third-party certification center. It will be able to prevent counterfeit certificate center attack more efficiently.

並列關鍵字

Self-certified scheme ； Elliptic Curve Cryptosystem ； Multi-document ； Threshold ； Signcryption scheme