📄 chap6-3-4.htm.primary
字号:
<html>
<head>
<title>Crack Tutorial</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<link rel="stylesheet" href="style/css.css" type="text/css">
<link rel="stylesheet" href="../STYLE/Css.css" type="text/css">
</head>
<body bgcolor="white" text="#000000" link="#004080" vlink="#004080" background="../image/Back.gif">
<p><a href="../catalog.htm">目录</a>＞＞第6章</p>
<p align="center" class="shadow1Copy"><b class="p3">第6章 软件保护技术</b></p>
<table width="80%" border="0" cellspacing="0" cellpadding="3" align="center" bgcolor="#bcbcbc" bordercolor="#111111" class="shadow1">
<tr>
<td class="shadow1" width="25%">
<div align="center"><a href="Chap6-1.htm"><font color="#FFFFFF">第一节 常见保护技巧</font></a></div>
</td>
<td class="shadow1" width="25%">
<div align="center"><a href="Chap6-2.htm"><font color="#FFFFFF">第二节 反跟踪技术</font></a></div>
</td>
<td class="shadow1" width="25%">
<div align="center"><a href="Chap6-3.htm"><font color="#FFFFFF">第三节 加密算法</font></a></div>
</td>
<td class="shadow1" width="25%">
<div align="center"><a href="Chap6-4.htm"><font color="#FFFFFF">第四节 软件保护建议</font></a></div>
</td>
</tr>
</table>
<p align="center"><span class="p9"><b>第三节 加密算法</b></span></p>
<table border="1" width="80%" cellpadding="5" bordercolor="#111111" bgcolor="#efefef" align="center" cellspacing="0">
<tr>
<td width="33%" valign="middle" align="center" class="p9" height="23">
<div align="left" class="p"><span class="p9"><span class="p9"> <span class="p9">1、<a href="Chap6-3-1.htm">RSA算法</a></span></span></span></div>
</td>
<td width="33%" valign="middle" align="center" class="p9" height="23">
<div align="left"><span class="p9"><span class="p9"> <span class="p9">2、<a href="Chap6-3-2.htm">DES算法</a></span></span></span></div>
</td>
<td width="34%" valign="top" class="p9" height="23">
<div align="left"><span class="p9"><span class="p9"> <span class="p9">3、<a href="Chap6-3-3.htm">ElGamal算法</a></span></span></span></div>
</td>
</tr>
<tr>
<td width="33%" valign="middle" align="center" class="p9" height="23">
<div align="left"><span class="p9"><span class="p9"> <span class="p9">4、<a href="Chap6-3-4.htm">DSA算法</a></span></span></span></div>
</td>
<td width="33%" valign="middle" align="center" class="p9" height="23">
<div align="left"><span class="p9"><span class="p9"> <span class="p9">5、<a href="Chap6-3-5.htm">MD5算法</a></span></span></span></div>
</td>
<td width="34%" valign="top" class="p9" height="23">
<div align="left"><span class="p9"><span class="p9"> <span class="p9">6、<a href="Chap6-3-6.htm">BLOWFISH算法</a></span></span></span></div>
</td>
</tr>
</table>
<p align="center"><span class="p9"><span class="p9"><span class="p9"><span class="p9"><span class="p9"><span class="p9"><b>4、DSA算法</b></span></span><b></b></span></span></span></span></p>
<p><font color="#000000"><span class="p9"> </span></font>Digital Signature Algorithm
(DSA)是Schnorr和ElGamal签名算法的变种，被美国NIST作为DSS(DigitalSignature Standard)。算法中应用了下述参数：<br>
<br>
p：L bits长的素数。L是64的倍数，范围是512到1024；<br>
q：p - 1的160bits的素因子；<br>
g：g = h^((p-1)/q) mod p，h满足h < p - 1, h^((p-1)/q) mod p > 1；<br>
x：x < q，x为私钥 ；<br>
y：y = g^x mod p ，( p, q, g, y )为公钥；<br>
H( x )：One-Way Hash函数。DSS中选用SHA( Secure Hash Algorithm )。<br>
p, q, g可由一组用户共享，但在实际应用中，使用公共模数可能会带来一定的威胁。签名及验证协议如下：<br>
<br>
1. P产生随机数k，k < q；<br>
2. P计算 r = ( g^k mod p ) mod q<br>
s = ( k^(-1) (H(m) + xr)) mod q<br>
签名结果是( m, r, s )。<br>
3. 验证时计算 w = s^(-1)mod q<br>
u1 = ( H( m ) * w ) mod q<br>
u2 = ( r * w ) mod q<br>
v = (( g^u1 * y^u2 ) mod p ) mod q<br>
若v = r，则认为签名有效。<br>
<br>
<font color="#000000"><span class="p9"> </span></font>DSA是基于整数有限域离散对数难题的，其安全性与RSA相比差不多。DSA的一个重要特点是两个素数公开，这<br>
样，当使用别人的p和q时，即使不知道私钥，你也能确认它们是否是随机产生的，还是作了手脚。RSA算法却作不到。</p>
<p align="center"><a href="../Catalog.htm"><img src="../image/navtoc.gif" width="84" height="23" border="0"></a><a href="Chap6-3-3.htm"><img src="../image/Navprev.gif" width="80" height="23" border="0"></a><a href="Chap6-3-5.htm"><img src="../image/navnext.gif" width="83" height="23" border="0"></a></p>
<hr width=735>
<div align="center"><span class="p9"><font size="2"><span class="p9"><font size="2"><span class="p9">Copyright
© 2000-2001 <a href="http://www.pediy.com/">KanXue Studio</a> All Rights
Reserved.</span></font></span></font></span></div>
</body>
</html>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -