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<?php
namespace lib\wechat;
class WechatCrypt
{
private $key;
private $iv;
private static $block_size = 32;
public function __construct($enckey)
{
$this->key = base64_decode($enckey . '=');
$this->iv = substr($this->key, 0, 16);
}
public function encrypt($data, $appid)
{
$str = $this->getRandomStr() . pack('N', strlen($data)) . $data . $appid;
$str = $this->enPKSC7($str);
$encrypted = openssl_encrypt($str, 'AES-256-CBC', $this->key, OPENSSL_ZERO_PADDING, $this->iv);
return $encrypted;
}
public function decrypt($data)
{
$decrypted = openssl_decrypt($data, 'AES-256-CBC', $this->key, OPENSSL_ZERO_PADDING, $this->iv);
if(!$decrypted) return false;
$decrypted = $this->dePKSC7($decrypted);
$content = substr($decrypted, 16, strlen($decrypted));
$len_list = unpack('N', substr($content, 0, 4));
$xml_len = $len_list[1];
$xml_content = substr($content, 4, $xml_len);
$from_appid = substr($content, $xml_len + 4);
return $xml_content;
}
private function enPKSC7($text)
{
$block_size = self::$block_size; //128:16、256:32
$text_length = strlen($text);
//计算需要填充的位数
$amount_to_pad = $block_size - ($text_length % $block_size);
if ($amount_to_pad == 0) {
$amount_to_pad = $block_size;
}
//获得补位所用的字符
$pad_chr = chr($amount_to_pad);
$tmp = "";
for ($index = 0; $index < $amount_to_pad; $index++) {
$tmp .= $pad_chr;
}
return $text . $tmp;
}
private function dePKSC7($text)
{
$block_size = self::$block_size; //128:16、256:32
$pad = ord(substr($text, -1));
if ($pad < 1 || $pad > $block_size) {
$pad = 0;
}
return substr($text, 0, (strlen($text) - $pad));
}
private function getRandomStr()
{
$str = '';
$str_pol = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyl';
$max = strlen($str_pol) - 1;
for ($i = 0; $i < 16; $i++) {
$str .= $str_pol[mt_rand(0, $max)];
}
return $str;
}
} |