Unity3d获取APK签名及公钥的方法

在Unity3d项目中获取APK包签名公钥的方法，核心思想就是通过JNI调用Android提供的方法。不过Unity3d提供了比JNI更上一层的类AndroidJavaObject以及继承它的AndroidJavaClass，帮助开发者省去很多工作。这两种类型的函数及内部原理可以看Unity3d官网，也可以反编译看里面的代码，直接说用法。

首先要获取到当前运行程序的Activity才好继续以后的操作。Unity3d在程序启动时记录下了这个值，可以通过UnityPlayer类的静态字段currentActivity来取得，UnityPlayer是由UnityPlayerActivity这个继承自Activity的类在onCreate时创建并传入当前Activity（详细流程可以通过jd-gui或反编译项目smali查看）。取到Activity以后就可以getPackageManager、getPackageInfo来获取到签名。得到的签名据说保存了公钥以及其他一些信息，这个没有具体深入了解，但是可以从签名获取到公钥是一定可以的，CertificateFactory的generateCertificate、getPublicKey方法取得最终值。下面是完整代码，注释对应java代码：

private byte[] GetSignature()

{

//Player = new UnityPlayer();

AndroidJavaClass Player = new AndroidJavaClass("com.unity3d.player.UnityPlayer");

//Activity = Player.currentActivity;

AndroidJavaObject Activity = Player.GetStatic("currentActivity");

//PackageManager = Activity.getPackageManager();

AndroidJavaObject PackageManager = Activity.Call("getPackageManager");

//GET_SIGNATURES = PackageManager.GET_SIGNATURES;

int GET_SIGNATURES = PackageManager.GetStatic("GET_SIGNATURES");

//PackageInfo = PackageManager.getPackageInfo("com.ztx.uni", PackageManager.GET_SIGNATURES);

AndroidJavaObject PackageInfo = PackageManager.Call("getPackageInfo", "com.ztx.uni", GET_SIGNATURES);

//Signatures = PackageInfo.signatures;

AndroidJavaObject[] Signatures = PackageInfo.Get("signatures");

//return Signatures[0].toByteArray();

return (Signatures != null && Signatures.Length > 0) ? Signatures[0].Call("toByteArray") : null;

}

private string GetPublicKey()

{

byte[] Signatures = GetSignature();

if (Signatures != null)

{

//CCertificateFactory = new CertificateFactory();

AndroidJavaClass CCertificateFactory = new AndroidJavaClass("java.security.cert.CertificateFactory");

//OCertFactory = CCertificateFactory.getInstance();

AndroidJavaObject OCertFactory = CCertificateFactory.CallStatic("getInstance", "X.509");

//OByteArrayInputStream = new ByteArrayInputStream(Signatures);

AndroidJavaObject OByteArrayInputStream = new AndroidJavaObject("java.io.ByteArrayInputStream", Signatures);

//OX509Certificate = OCertFactory.generateCertificate(OByteArrayInputStream);

AndroidJavaObject OX509Certificate = OCertFactory.Call("generateCertificate", OByteArrayInputStream);

//OPublicKey = OX509Certificate.getPublicKey();

AndroidJavaObject OPublicKey = OX509Certificate.Call("getPublicKey");

string publickey = OPublicKey.Call("toString");

AndroidJavaObject CString = new AndroidJavaObject("java/lang/String", publickey);

int start = CString.Call("indexOf", "modulus");

int end = CString.Call("indexOf", "public");

if (start >= 0 && end >= 0)

{

return CString.Call("substring", start + 8, end - 1);

}

}

return null;

}在GetPublicKey()中取得的OPublicKey是如下的形式：

OpenSSLRSAPublicKey

{modulus=d6931904dec60b24b1edc762e0d9d8253e3ecd6ceb1de2ff068ca8e8bca8cd6bd3786ea70aa76ce

60ebb0f993559ffd93e77a943e7e83d4b64b8e4fea2d3e656f1e267a81bbfb230b578c20443be4c7218b846f

5211586f038a14e89c2be387f8ebecf8fcac3da1ee330c9ea93d0a7c3dc4af350220d50080732e0809717ee6

a053359e6a694ec2cb3f284a0a466c87a94d83b31093a67372e2f6412c06e6d42f15818dffe0381cc0cd444d

a6cddc3b82458194801b32564134fbfde98c9287748dbf5676a540d8154c8bbca07b9e247553311c46b9af76

fdeeccc8e69e7c8a2d08e782620943f99727d3c04fe72991d99df9bae38a0b2177fa31d5b6afee91f,publicExponent=3}而我们要的只是其中的256位公钥，所以在函数后面取了modulus和publicExponent之间的值。至此全部工作结束，很简单吧，如果在ndk中做公钥提取也是这个道理，不过要写很多很多代码。转载地址:http://m.blog.csdn.net/blog/s10141303/38260469