PHP RSA2 签名算法

<?php
/**
 * Created by PhpStorm.
 * User: kurtchen
 * Date: 2018/4/12
 * Time: 20:03
 */
class Rsa2
{
    private static $PRIVATE_KEY ="私钥内容";
    private static $PUBLIC_KEY  ="公钥内容";
    /**
     * 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 = '')
    {
      //  var_dump(self::getPrivateKey());die;
        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
        );
    }
}

$rsa2 = new Rsa2();
$data = 'mydata'; //待签名字符串
$strSign = $rsa2->createSign($data);      //生成签名
$is_ok = $rsa2->verifySign($data, $strSign); //验证签名