function sign($data) {
  //讀取私鑰文件
  $priKey = file_get_contents('key/rsa_private_key.pem');
  //轉(zhuǎn)換為openssl密鑰，必須是沒有經(jīng)過pkcs8轉(zhuǎn)換的私鑰
  $res = openssl_get_privatekey($priKey);
  //調(diào)用openssl內(nèi)置簽名方法，生成簽名$sign
  openssl_sign($data, $sign, $res);
  //釋放資源
  openssl_free_key($res);
  return $sign;
}

function verify($data, $sign) {
  //讀取支付寶公鑰文件
  $pubKey = file_get_contents('key/alipay_public_key.pem');
  //轉(zhuǎn)換為openssl格式密鑰
  $res = openssl_get_publickey($pubKey);
  //調(diào)用openssl內(nèi)置方法驗簽，返回bool值
  $result = (bool)openssl_verify($data, $sign, $res);
  //釋放資源
  openssl_free_key($res);
  return $result;
}

function decrypt($content) {
  //讀取商戶私鑰
  $priKey = file_get_contents('key/rsa_private_key.pem');
  //轉(zhuǎn)換為openssl密鑰，必須是沒有經(jīng)過pkcs8轉(zhuǎn)換的私鑰
  $res = openssl_get_privatekey($priKey);
  //聲明明文字符串變量
  $result = '';
  //循環(huán)按照128位解密
  for($i = 0; $i < strlen($content)/128; $i++ ) {
    $data = substr($content, $i * 128, 128);
  //拆分開長度為128的字符串片段通過私鑰進行解密，返回$decrypt解析后的明文
    openssl_private_decrypt($data, $decrypt, $res);
  //明文片段拼接
    $result .= $decrypt;
  }
  //釋放資源
  openssl_free_key($res);
  //返回明文
  return $result;
}