数据加密算法
<DIV><P style="TEXT-ALIGN: left; LINE-HEIGHT: 19.5pt; TEXT-INDENT: 21pt; MARGIN: 7.5pt 0cm; BACKGROUND: #f8f8f8; mso-pagination: widow-orphan" class=MsoNormal align=left><B style="mso-bidi-font-weight: normal"><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; FONT-SIZE: 18pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt"><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN></B><B style="mso-bidi-font-weight: normal"><SPAN style="FONT-FAMILY: 宋体; COLOR: black; FONT-SIZE: 18pt; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">数据加密算法</SPAN></B><B style="mso-bidi-font-weight: normal"><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; FONT-SIZE: 18pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman"> </FONT></SPAN></B></P>
<P style="TEXT-ALIGN: left; LINE-HEIGHT: 19.5pt; TEXT-INDENT: 21pt; MARGIN: 7.5pt 0cm; BACKGROUND: #f8f8f8; mso-pagination: widow-orphan" class=MsoNormal align=left><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">数据加密算法有很多种</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman"></FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">，密码算法标准化是信息化社会发展得必然趋势，是世界各国保密通信领域得一个重要课题。按照发展进程来分，经历了古典密码、对称密钥密码和公开密钥密码阶段，古典密码算法有替代加密、置换加密；对称加密算法包括</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">DES</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">和</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">AES</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">；非对称加密算法包括</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">RSA </FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">、背包密码、</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">McEliece</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">密码、</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">Rabin</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">、椭圆曲线、</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">EIGamal D_H</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">等。目前在数据通信中使用最普遍的算法有</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">DES</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">算法、</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">RSA</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">算法和</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">PGP</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">算法等。</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman"> </FONT></SPAN></P>
<P style="TEXT-ALIGN: left; LINE-HEIGHT: 19.5pt; TEXT-INDENT: 21pt; MARGIN: 7.5pt 0cm; BACKGROUND: #f8f8f8; mso-pagination: widow-orphan" class=MsoNormal align=left><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">(1)DES</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">加密算法</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">(</FONT><a href="http://www.njaxd.cn/" target="_blank"><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥" lang=EN-US><SPAN lang=EN-US><FONT color=#800080>数据加密</FONT></SPAN></SPAN></A></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">标准</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">)</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">。</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman"> </FONT></SPAN></P>
<P style="TEXT-ALIGN: left; LINE-HEIGHT: 19.5pt; TEXT-INDENT: 21pt; MARGIN: 7.5pt 0cm; BACKGROUND: #f8f8f8; mso-pagination: widow-orphan" class=MsoNormal align=left><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">DES</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">是一种对二元数据进行加密的算法，数据分组长度为</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">64</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">位，密文分组长度也是</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">64</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">位，使用的密钥为</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">64</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">位，有效密钥长度为</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">56</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">位，有</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">8</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">位用于奇偶校验，解密时的过程和加密时相似，但密钥的顺序正好相反。</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman"> </FONT></SPAN></P>
<P style="TEXT-ALIGN: left; LINE-HEIGHT: 19.5pt; TEXT-INDENT: 21pt; MARGIN: 7.5pt 0cm; BACKGROUND: #f8f8f8; mso-pagination: widow-orphan" class=MsoNormal align=left><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">DES</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">算法的弱点是不能提供足够的安全性，因为其密钥容量只有</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">56</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">位。由于这个原因，后来又提出了三重</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">DES</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">或</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">3DES</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">系统，使用</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">3</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">个不同的密钥对数据块进行</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">(</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">两次或</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">)</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">三次加密，该方法比进行普通加密的三次块。其强度大约和</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">112</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">比特的密钥强度相当。</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US></SPAN></P>
<P style="TEXT-ALIGN: left; LINE-HEIGHT: 19.5pt; TEXT-INDENT: 21pt; MARGIN: 7.5pt 0cm; BACKGROUND: #f8f8f8; mso-pagination: widow-orphan" class=MsoNormal align=left><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">(2)RSA</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">算法</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman"> </FONT></SPAN></P>
<P style="TEXT-ALIGN: left; LINE-HEIGHT: 19.5pt; TEXT-INDENT: 21pt; MARGIN: 7.5pt 0cm; BACKGROUND: #f8f8f8; mso-pagination: widow-orphan" class=MsoNormal align=left><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">RSA</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">算法既能用于数据加密，也能用于数字签名，</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">RSA</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">的理论依据为：寻找两个大素数比较简单，而将它们的乘积分解开则异常困难。在</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">RSA</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">算法中，包含两个密钥，</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><a href="http://www.njaxd.cn/" target="_blank"><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥" lang=EN-US><SPAN lang=EN-US><FONT color=#800080>加密</FONT></SPAN></SPAN></A></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">密钥</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">PK</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">，和解密密钥</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">SK</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">，加密密钥是公开的，其加密与解密方程为：</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman"> </FONT></SPAN></P>
<P style="TEXT-ALIGN: left; LINE-HEIGHT: 19.5pt; TEXT-INDENT: 21pt; MARGIN: 7.5pt 0cm; BACKGROUND: #f8f8f8; mso-pagination: widow-orphan" class=MsoNormal align=left><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">其中</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">n=p×q</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">，</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">P</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">∈</SPAN><SPAN style="COLOR: black; mso-bidi-font-size: 10.5pt; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman"></FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">，</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">p</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">和</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">q</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">均为大于</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">10100</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">的素数，这两个素数是保密的。</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman"> </FONT></SPAN></P>
<P style="TEXT-ALIGN: left; LINE-HEIGHT: 19.5pt; TEXT-INDENT: 21pt; MARGIN: 7.5pt 0cm 0pt; BACKGROUND: #f8f8f8; mso-pagination: widow-orphan" class=MsoNormal align=left><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">RSA</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">算法的优点是密钥空间大，缺点是加密速度慢，如果</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">RSA</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">和</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">DES</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">结合使用，则正好弥补</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">RSA</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">的缺点。即</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">DES</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">用于明文加密，</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">RSA</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">用于</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">DES</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">密钥的加密。由于</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">DES</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">加密速度快，适合加密较长的报文；而</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">RSA</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">可解决</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman">DES</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; COLOR: black; mso-ascii-font-family: ˎ̥; mso-hansi-font-family: ˎ̥; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">密钥分配的问题。</SPAN><SPAN style="FONT-FAMILY: ˎ̥; COLOR: black; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt" lang=EN-US><FONT face="Times New Roman"> </FONT></SPAN></P>
<P style="MARGIN: 0cm 0cm 0pt" class=MsoNormal><SPAN lang=EN-US><FONT face="Times New Roman"> </FONT></SPAN></P></DIV>
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