應用RSA密碼法於辦公室文件處理

Abstract

傳統的辦公室文件作業是以紙張為主，在其確認及保密上，可以由文件上 的簽名或蓋章來驗證其有效性及可利用卷宗及檔案櫃或保險櫃等來保護其 隱密性。但在電子文件方面，因為資料是以電子信號表示，所以無法用人 工的簽名或蓋章來驗證文件，也無法用卷宗及檔案櫃或保險櫃等來保護資 料。而本文所探討的，便是如何利用密碼學的技術，來克服電子文件所面 臨隱密性及確認性的問題；在此，我們建議了三種應用ＲＳＡ於辦公室文 件之簽章及保密方法：(1)RSA(M)，(2)RSA(MD)，(3)RSA(MD) +DES(M)。 此處M為文件本身，MD為M的摘要(Message Digest)。本文是以劉國興等人 [12]的系統架構為藍本，以及根據所引用企業的組織編制、公文流程等等 ，規劃出一應用系統，並引例說明；希望能夠為辦公室文件電子化，提出 一具有簽章驗證及保密功能的應用系統範例，作為企業界辦公室自動化之 參考。 This thesis intends to apply cryptography technology to preserve secrecy and privacy, as well as offer authentication and non-repudiation, for electronic documents in offices. Three methods of based on RSA were recommended :(1)RSA(M), (2)RSA( MD), (3)RSA(MD)+DES(M). The first uses RSA to encrypt the whole document. The second utilizes RSA to sign on the message digest( MD) produced from the document, while the whole document is transmitted in the plaintext form. The last method is similar to the second except that the plaintext is encrypted under DES before transmission. Advantages and disadvantages of the three methods were discussed. An example system from a local business firm was developed to demonstrate the application of the three methods.