无法通过服务器端验证Google Play应用内结算v3购买

Question

I have implemented Android In App Billing V3 in my application. I am able to do purchase from the Google Play store and got the success full response.below is the sample response

Purchase data: {"orderId":"125454212.45454544794","packageName":"com.myapp.book.android","productId":"com.bookreader.sonic.the.hedgehog.five.02232010","purchaseTime":1404914019181,"purchaseState":0,"developerPayload":"com.archiereader.sonic.the.hello.five.2454542121010paid","purchaseToken":"sdsdsdsaskmg.AO-J1OzmoW2l-6GMP31IOyPtjY65cHMinYNWEeeyYIhr88g1Z7ftw7KElUTsi-ALaIyCKPWZr3cn9J3l9ypXPrzQB3SK94YTlI-AdbGU8guqBlAp_huwiJr36GIMQdX-ygwJyQWxOO0ThJvzsSziKnV_ZttyV8Ey-8DR2xaY85fjvnMRbBt05TaWVWCckdlCWPuSyCMgMbBX"}

Data signature: Bcklq9v2isbE92Zljlg2Tgapnfsadasd2xec3Z0qK6gk5D7Gu3T/xXCTs6KM8lKFiW1s5LGeQgIxJGxmodRSXGJJIlTknDcZDU2oQB+d5vM/wyn0PG0VWJa2AbjYMkIqF+G/OE3fsieYxkAM4CatnH7ijpnCsZmyB3YwMAlzbd/qGWxnOBCp7TMPssadsdCpbt3BUf6c56adwe545EXJUTOeMZEX0yeOqtmfQkgFFnUSeNtbbkeCClLBWXbuorrtS2J4cCqgbCrkfEeFyXwgGYJnVuE1oSZtaHLhejIrWnRJsdasdwddBS69Tjcu8IBgB7T1oDpHN6VZhChECno9sVhYaLqSn9fT+m9D3G5jaUMWBFA==

I am passing the below data to my server

payload.put("receiptSignature",  signature);
payload.put("receiptData", Base64.encode(receipt.toString().getBytes()));
payload.put("apikey" marketkey);

And I am validating my purchase at my server side using this method. $result = openssl_verify($receipt, $signature, $key);

I am getting always failed result using the above code. what I am doing wrong here. Can any one please help me in resolving this issue. Any help would be appreciate....

Regards, Ganesh