PHP函数crypt()的功能介绍_PHP教程-php教程-PHP中文网

PHP函数crypt()的功能介绍_PHP教程

php中文网

发布： 2016-07-15 13:30:47

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我们知道在中有实现数据加密的功能，我们今天将为大家介绍的是其中一个可以实现数据加密功能的函数——php函数crypt()。作为php函数crypt()的一个例子，考虑这样一种情况，你希望创建一段php脚本程序限制对一个目录的访问，只允许能够提供正确的用户名和口令的用户访问这一目录。

我将把资料存储在我喜欢的数据库MySQL的一个表中。下面我们以创建这个被称作members的表开始我们的例子：

<ol class="dp-xml"><li class="alt"><span><span>mysql</span><span class="tag">></span><span>CREATE TABLE members (   </span></span></li><li><span>-</span><span class="tag">></span><span>username CHAR(14) NOT NULL,   </span></li><li class="alt"><span>-</span><span class="tag">></span><span>password CHAR(32) NOT NULL,   </span></li><li><span>-</span><span class="tag">></span><span>PRIMARY KEY(username)   </span></li><li class="alt"><span>-</span><span class="tag">></span><span>);  </span></li></ol>

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然后，我们假定下面的数据已经存储在该表中：

用户名密码
clark keloD1C377lKE
bruce ba1T7vnz9AWgk
peter paLUvRWsRLZ4U

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PHP函数crypt()中的这些加密的口令对应的明码分别是kent、banner和parker。注意一下每个口令的前二个字母，这是因为我使用了下面的代码，根据口令的前二个字母创建干扰串的：

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<ol class="dp-xml"><li class="alt"><span><span>$enteredPassword.   </span></span></li><li><span>$</span><span class="attribute">salt</span><span> = </span><span class="attribute-value">substr</span><span>($enteredPassword, 0, 2);   </span></li><li class="alt"><span>$</span><span class="attribute">userPswd</span><span> = </span><span class="attribute-value">crypt</span><span>($enteredPassword, $salt);   </span></li><li><span>// $userPswd然后就和用户名一起存储在MySQL 中  </span></li></ol>

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我将使用Apache的口令-应答认证配置提示用户输入用户名和口令，一个鲜为人知的有关PHP的信息是，它可以把Apache 的口令-应答系统输入的用户名和口令识别为$PHP_AUTH_USER和$PHP_AUTH_PW，我将在身份验证脚本中用到这二个变量。花一些时间仔细阅读下面的脚本，多注意一下其中的解释，以便更好地理解下面的代码：

PHP函数crypt()和Apache的口令-应答验证系统的应用

<ol class="dp-xml"><li class="alt"><span><span class="tag"><</span><span> ?php   </span></span></li><li><span>$</span><span class="attribute">host</span><span> = </span><span class="attribute-value">"localhost"</span><span>;   </span></li><li class="alt"><span>$</span><span class="attribute">user</span><span> = </span><span class="attribute-value">"zorro"</span><span>;   </span></li><li><span>$</span><span class="attribute">pswd</span><span> = </span><span class="attribute-value">"hell odolly"</span><span>;   </span></li><li class="alt"><span>$</span><span class="attribute">db</span><span> = </span><span class="attribute-value">"users"</span><span>;   </span></li><li><span>// Set authorization to False   </span></li><li class="alt"><span>$</span><span class="attribute">authorization</span><span> = </span><span class="attribute-value">0</span><span>;   </span></li><li><span>// Verify that user has entered<br /> username and password   </span></li><li class="alt"><span>if (isset($PHP_AUTH_USER) && <br />isset($PHP_AUTH_PW)) :   </span></li><li><span>mysql_pconnect($host, $user, <br />$pswd) or die("Can't connect to MySQL   </span></li><li class="alt"><span>server!");   </span></li><li><span>mysql_select_db($db) or die<br />("Can't select database!");   </span></li><li class="alt"><span>// Perform the encryption   </span></li><li><span>$</span><span class="attribute">salt</span><span> = </span><span class="attribute-value">substr</span><span>($PHP_AUTH_PW, 0, 2);   </span></li><li class="alt"><span>$</span><span class="attribute">encrypted_pswd</span><span> = crypt($PHP_AUTH_PW, $salt);   </span></li><li><span>// Build the query   </span></li><li class="alt"><span>$</span><span class="attribute">query</span><span> = "SELECT username FROM members WHERE   </span></li><li><span class="attribute">username</span><span> = '$PHP_AUTH_USER' AND   </span></li><li class="alt"><span class="attribute">password</span><span> = '$encrypted_pswd'";   </span></li><li><span>// Execute the query   </span></li><li class="alt"><span>if (mysql_numrows(mysql_query($query)) == 1) :   </span></li><li><span>$</span><span class="attribute">authorization</span><span> = </span><span class="attribute-value">1</span><span>;   </span></li><li class="alt"><span>endif;   </span></li><li><span>endif;   </span></li><li class="alt"><span>// confirm authorization   </span></li><li><span>if (! $authorization) :   </span></li><li class="alt"><span>header('WWW-Authenticate: <br />Basic </span><span class="attribute">realm</span><span>=</span><span class="attribute-value">"Private"</span><span>');   </span></li><li><span>header('HTTP/1.0 401 Unauthorized');   </span></li><li class="alt"><span>print "You are unauthorized <br />to enter this area.";   </span></li><li><span>exit;   </span></li><li class="alt"><span>else :   </span></li><li><span>print "This is the secret data!";   </span></li><li class="alt"><span>endif;   </span></li><li><span class="tag">?></span><span>  </span></li></ol>

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上面就是一个核实用户访问权限的简单身份验证系统。在使用PHP函数crypt()保护重要的机密资料时，记住在缺省状态下使用的PHP函数crypt()并不是最安全的，只能用在对安全性要求较低的系统中，如果需要较高的安全性能，就需要我在本篇文章的后面介绍的算法。