我使用的接口是退款接口：

https://api.mch.weixin.qq.com/v3/refund/domestic/refunds

签名生成代码如下，服务商和商户号证书都试了，都无法退款成功。返回信息是签名错误。

$url传入的是退款接口地址，证书序列号和商户号都修改过服务商和特约商户的了，都跑不通。

public function getAuthorization($http_method = "POST", $body = [], $url = "v3/pay/partner/transactions/jsapi"): string
{
    $serial_no = $this->merchantCertificateSerial; // 商户证书序列号
    $mchid = $this->config['service_member'];  // 商户号
    $timestamp = time();
    $nonce = $this->nonce_str();
    $url_parts = parse_url($url);

    $canonical_url = ($url_parts['path'] . (!empty($url_parts['query']) ? "?${url_parts['query']}" : ""));
    $message = $http_method . "\n" .
        $canonical_url . "\n" .
        $timestamp . "\n" .
        $nonce . "\n" .
        $body . "\n";

    openssl_sign($message, $raw_sign, $this->merchantPrivateKeyInstance, 'sha256WithRSAEncryption');
    $sign = base64_encode($raw_sign);

    return sprintf('mchid="%s",nonce_str="%s",timestamp="%d",serial_no="%s",signature="%s"',
        $mchid, $nonce, $timestamp, $serial_no, $sign);
}

是不是这里的服务没授权导致的，但是我使用商户号进行退款仍然提示签名错误，错误信息如下

{

    "code": "SIGN_ERROR",

    "detail": {

        "detail": {

            "issue": "sign not match"

        },

        "field": "signature",

        "location": "authorization",

        "sign_information": {

            "method": "POST",

            "sign_message_length": 324,

            "truncated_sign_message": "POST\n/v3/refund/domestic/refunds\n1693894402\nwwGNussqESygThKOPRGplkjMAWuBnFoB\n{\"out_tr\n",

            "url": "/v3/refund/domestic/refunds"

        }

    },

    "message": "错误的签名，验签失败"

}