如何使用Java JDK 1.7在我的第三方服务器上对GKLocalPlayer进行身份验证？

使用此处概述的Apple的Game Center身份验证验证步骤，已使用Java实现了以下验证逻辑。但是，这总是失败。

import java.net.URL;

import java.nio.ByteBuffer;

import java.nio.ByteOrder;

import java.security.KeyPair;

import java.security.KeyPairGenerator;

import java.security.MessageDigest;

import java.security.PrivateKey;

import java.security.PublicKey;

import java.security.SecureRandom;

import java.security.Signature;

import java.security.cert.Certificate;

import java.security.cert.CertificateFactory;

import java.security.spec.AlgorithmParameterSpec;

import java.util.Arrays;

import javax.crypto.Cipher;

import javax.xml.bind.DatatypeConverter;

public class Verifier {

    public static void main(String[] args) {

        verify1();   

    }



    public static void verify1() {

        try {

            byte[] playerID = "G:90082947".getBytes("UTF-8");

            byte[] bundleID = "com.appledts.GameCenterSamples".getBytes("UTF-8");



            long ts = 1392078336714L;

            final ByteBuffer tsByteBuffer = ByteBuffer.allocate(8);

            tsByteBuffer.order(ByteOrder.BIG_ENDIAN);

            tsByteBuffer.putLong(ts);           

            byte[] timestamp = tsByteBuffer.array();



            byte[] salt = DatatypeConverter.parseBase64Binary("xmvbZQ==");



            byte[] sigToCheck = DatatypeConverter.parseBase64Binary("AmyNbm+7wJOjXv6GXI/vAEcl6gSX1AKxPr3GeExSYCiaxVaAeIvC23TWtp1/Vd/szfq1r1OzwrvkHeSSiskWMsMXaGQWUmiGtCnf9fqBU75T5PwNLCj4H9Nd5QENCMV/CFgVyGEi4X6Wlp18kqJPk/ooS6jLJwcWIe6DyrR1bQHl6YzKTfB4ACl2JEccBDz8dArKTrh4vFcQF4a+DtERm283Y2ue1DwG8lqWrYhsRO5v7vrW3lVpn5t25QXc+Y35zJ/il+lZJxKAgASwrKaq3G8RStdkeXCER23fSYhTmbLFqkFRWnmzu38hmLt5/iivUbm8NgELXP0SyQoYLMvfmA==");



            ByteBuffer dataBuffer = ByteBuffer.allocate(playerID.length+bundleID.length+8+salt.length)

                .put(playerID)

                .put(bundleID)

                .put(timestamp)

                .put(salt);





            Certificate cert = CertificateFactory.getInstance("X.509")

                    .generateCertificate(new URL("https://sandbox.gc.apple.com/public-key/gc-sb.cer").openConnection().getInputStream());





            Signature sig = Signature.getInstance("SHA1withRSA");

            sig.initVerify(cert);



            sig.update(dataBuffer);



            final boolean verify = sig.verify(sigToCheck);

            System.out.println("signature verifies: " + verify);                            



        } catch (Exception e) {            

            e.printStackTrace();

        }

    }        

}

从iOS 7客户端向服务器传输数据时，不会丢失任何比特。通过将二进制位写入来自xCode和Java的文件中，生成它们的十六进制，并查看是否存在任何差异（请注意，差异仅显示文件名diff）来验证这一点：

$ xxd -i salt_Java.txt salt_java.xxd

$ xxd -i salt_xcode.txt salt_xcode.xxd

$ xxd -i sigToCheck_Java.txt sigToCheck_java.xxd

$ xxd -i sigToCheck_xcode.txt sigToCheck_xcode.xxd

$ diff salt_java.xxd salt_xcode.xxd 

1c1

< unsigned char salt_Java_txt[] = {

---

> unsigned char salt_xcode_txt[] = {

4c4

< unsigned int salt_Java_txt_len = 4;

---

> unsigned int salt_xcode_txt_len = 4;

$ diff sigToCheck_java.xxd sigToCheck_xcode.xxd 

1c1

< unsigned char sigToCheck_Java_txt[] = {

---

> unsigned char sigToCheck_xcode_txt[] = {

25c25

< unsigned int sigToCheck_Java_txt_len = 256;

---

> unsigned int sigToCheck_xcode_txt_len = 256;

$ 

我认为这失败是因为Signature类使用了底层Java库，因为此处列出的Objective-C解决方案似乎可以成功验证相同的凭据。

我的下一个尝试是使用Java的[Cipher]和[MessageDigest]库而不是[Signature]库，但这也失败了。我怀疑在使用提供的签名位检查签名摘要位之前，还缺少其他步骤。

final MessageDigest md = MessageDigest.getInstance("SHA1");

byte[] digest = md.digest(dataBuffer.array());

// RSA decrypt

Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");

cipher.init(Cipher.DECRYPT_MODE, cert);

byte[] decrypted = cipher.doFinal(sigToCheck);    



System.out.println("signature verifies: " + Arrays.equals(digest, decrypted));

在上面发布的解决方案中，是否可以使用其他方法来验证数字签名或存在任何空白？