PHPの暗号化と復号化

<code><span>$urlstr</span> = urlencode(<span>"我是codekissyoung"</span>);
<span>echo</span>  urldecode(<span>$urlstr</span>);</code>

<code><span>echo</span>  md5(<span>"hehexiix23"</span>);
<span>echo</span> crypt(<span>$some_string</span>,<span>'keyvalue'</span>);
<span>$str</span> = <span>'apple'</span>;
<span>if</span> (sha1(<span>$str</span>) === <span>'d0be2dc421be4fcd0172e5afceea3970e2f3d940'</span>) {
    <span>echo</span><span>"Would you like a green or red apple?"</span>;
}</code>

<code>base64_encode(<span>$string</span>);
base64_decode(<span>$string</span>);
convert_uudecode(<span>$str</span>);
convert_uuencode(<span>$str</span>);</code>