php自定义加密解决实现代码

<?php
// 说明：PHP 写的加密函数,支持私人密钥

 
function keyED($txt,$encrypt_key)
{
    $encrypt_key = md5($encrypt_key);
    $ctr=0;
    $tmp = "";
    for ($i=0;$i<strlen($txt);$i++)
    {
        if ($ctr==strlen($encrypt_key)) $ctr=0;
        $tmp.= substr($txt,$i,1) ^ substr($encrypt_key,$ctr,1);
        $ctr++;
    }
    return $tmp;
}  
 
function encrypt($txt,$key)
{
    srand((double)microtime()*1000000);
    $encrypt_key = md5(rand(0,32000));
    $ctr=0;
    $tmp = "";
    for ($i=0;$i<strlen($txt);$i++)
    {
        if ($ctr==strlen($encrypt_key)) $ctr=0;
        $tmp.= substr($encrypt_key,$ctr,1) . (substr($txt,$i,1) ^ substr($encrypt_key,$ctr,1));
        $ctr++;
    }
    return keyED($tmp,$key);
}  
 
function decrypt($txt,$key)
{
    $txt = keyED($txt,$key);
    $tmp = "";
    for ($i=0;$i<strlen($txt);$i++)
    {
        $md5 = substr($txt,$i,1);
        $i++;
        $tmp.= (substr($txt,$i,1) ^ $md5);
    }
    return $tmp;
} 
 
$key = "YITU.org";
$string = "我是加密字符";  
 
// encrypt $string, and store it in $enc_text
$enc_text = encrypt($string,$key);  
 
// decrypt the encrypted text $enc_text, and store it in $dec_text
$dec_text = decrypt($enc_text,$key);  
 
print "加密的 text : $enc_text <Br> ";
print "解密的 text : $dec_text <Br> ";
?>