PHP での単純な対称暗号化アルゴリズムの実装

<?php
$content = "大家好，我是中国人，你是谁";
 
/**
* 简单对称加密算法之加密
* @param String $string 需要加密的字串
* @param String $skey 加密EKY
* @return String
*/
function encode($string = &#39;&#39;, $skey = &#39;wenzi&#39;) {
$strArr = str_split(base64_encode($string));
$strCount = count($strArr);
foreach (str_split($skey) as $key => $value)
 $key < $strCount && $strArr[$key].=$value;
return str_replace(array(&#39;=&#39;, &#39;+&#39;, &#39;/&#39;), array(&#39;O0O0O&#39;, &#39;o000o&#39;, &#39;oo00o&#39;), join(&#39;&#39;, $strArr));
}
 
/**
* 简单对称加密算法之解密
* @param String $string 需要解密的字串
* @param String $skey 解密KEY
* @return String
*/
function decode($string = &#39;&#39;, $skey = &#39;wenzi&#39;) {
$strArr = str_split(str_replace(array(&#39;O0O0O&#39;, &#39;o000o&#39;, &#39;oo00o&#39;), array(&#39;=&#39;, &#39;+&#39;, &#39;/&#39;), $string), 2);
$strCount = count($strArr);
foreach (str_split($skey) as $key => $value)
 $key <= $strCount && $strArr[$key][1] === $value && $strArr[$key] = $strArr[$key][0];
return base64_decode(join(&#39;&#39;, $strArr));
}
 
echo &#39;<pre class="brush:php;toolbar:false">&#39;;
echo "string : " . $content . " <br />";
echo "encode : " . ($enstring = encode($content)) . &#39;<br />&#39;;
echo "decode : " . decode($enstring);
 
exit();