class Rsa2
    {
        private static $PRIVATE_KEY = 'rsa_private_key.pem 内容';
        private static $PUBLIC_KEY  = 'rsa_public_key.pem 内容';

        /**
         * 获取私钥
         * @return bool|resource
         */
        private static function getPrivateKey()
        {
            $privKey = self::$PRIVATE_KEY;
            return openssl_pkey_get_private($privKey);
        }

        /**
         * 获取公钥
         * @return bool|resource
         */
        private static function getPublicKey()
        {
            $publicKey = self::$PUBLIC_KEY;
            return openssl_pkey_get_public($publicKey);
        }

        /**
         * 创建签名
         * @param string $data 数据
         * @return null|string
         */
        public function createSign($data = '')
        {
            if (!is_string($data)) {
                return null;
            }
            return openssl_sign(
                        $data,
                        $sign,
                        self::getPrivateKey(),
                        OPENSSL_ALGO_SHA256
                      ) ? base64_encode($sign) : null;
        }

        /**
         * 验证签名
         * @param string $data 数据
         * @param string $sign 签名
         * @return bool
         */
        public function verifySign($data = '', $sign = '')
        {
            if (!is_string($sign) || !is_string($sign)) {
                return false;
            }
            return (bool)openssl_verify(
                          $data,
                          base64_decode($sign),
                          self::getPublicKey(),
                          OPENSSL_ALGO_SHA256
                        );
        }
    }

    require_once "Rsa2.php";
    $rsa2 = new Rsa2();

    $data = 'my data'; //待签名字符串

    $strSign = $rsa2->createSign($data);      //生成签名
    var_dump($strSign);

    $is_ok = $rsa2->verifySign($data, $sign); //验证签名
    var_dump($is_ok);