在ndk中获取apk签名文件的MD5值

最近在弄ndk，需要做一个用纯C校验签名的功能，也看了一些帖子，主要是参考下面两个：

主要思路是参考这个帖子，java代码和c代码都是，但是这个帖子里有几个小错误

http://blog.youkuaiyun.com/lgl1170860350/article/details/46348965

有的地方看了下这个帖：

http://blog.youkuaiyun.com/leifengpeng/article/details/52681196

因为同时用的是unity3D，没法传context参数给我，还顺便研究了下怎么获取context，参考贴：

http://blog.youkuaiyun.com/xiaogazhang/article/details/46891139

 

我的代码：

	bool soulgameCheckMD5InPureC(jobject context,JNIEnv *env){
		SGLOGD("soulgameCheckMD5InPureC() begin!");

		//
		jclass tem_class;
		jmethodID tem_method;
		jclass class_context = env->GetObjectClass(context);

		//PackageInfo localPackageInfo = context.getPackageManager()
		tem_method = env->GetMethodID(class_context, "getPackageManager", "()Landroid/content/pm/PackageManager;");
		jobject obj_package_manager = env->CallObjectMethod(context, tem_method);
		if(obj_package_manager == NULL){
			SGLOGD("soulgameCheckMD5InPureC() getPackageManager failed!");
			return false;
		}

		// getPackageName
		tem_method = env->GetMethodID(class_context, "getPackageName", "()Ljava/lang/String;");
		jobject obj_package_name = env->CallObjectMethod(context, tem_method);
		env->DeleteLocalRef(class_context);
		env->DeleteLocalRef(context);
		if(obj_package_name == NULL){
			SGLOGD("soulgameCheckMD5InPureC() getPackageName failed!");
			return false;
		}

		// getPackageInfo
		tem_class = env->GetObjectClass(obj_package_manager);
		tem_method = env->GetMethodID(tem_class, "getPackageInfo", "(Ljava/lang/String;I)Landroid/content/pm/PackageInfo;");
		jobject obj_package_info = env->CallObjectMethod(obj_package_manager, tem_method, obj_package_name, 64);
		env->DeleteLocalRef(obj_package_name);
		env->DeleteLocalRef(obj_package_manager);
		if(obj_package_info == NULL){
			SGLOGD("soulgameCheckMD5InPureC() getPackageInfo failed!");
			return false;
		}

		// Signature[] arrayOfSignature = localPackageInfo.signatures;
		tem_class = env->GetObjectClass(obj_package_info);
		jfieldID fieldID_signatures = env->GetFieldID(tem_class, "signatures", "[Landroid/content/pm/Signature;");
		// Signature localSignature = arrayOfSignature[0];
		jobject signatur = env->GetObjectField(obj_package_info, fieldID_signatures);
		jobjectArray signatures = (jobjectArray)(signatur);
		jobject signature = env->GetObjectArrayElement(signatures, 0);
		env->DeleteLocalRef(signatures);
		env->DeleteLocalRef(obj_package_info);
		if(signatur == NULL){
			SGLOGD("soulgameCheckMD5InPureC() signatures failed!");
			return false;
		}

		// localSignature.toByteArray()
		tem_class = env->GetObjectClass(signature);
		tem_method = env->GetMethodID(tem_class, "toByteArray", "()[B");
		jobject obj_sign_byte_array = env->CallObjectMethod(signature, tem_method);// 这个就是拿到的签名byte数组
		env->DeleteLocalRef(signature);
		env->DeleteLocalRef(tem_class);
		if(obj_sign_byte_array == NULL){
			SGLOGD("soulgameCheckMD5InPureC() toByteArray failed!");
			return false;
		}

		// MessageDigest localMessageDigest = MessageDigest.getInstance("MD5");
		jclass class_MessageDigest = env->FindClass( "java/security/MessageDigest");
		tem_method = env->GetStaticMethodID( class_MessageDigest, "getInstance", "(Ljava/lang/String;)Ljava/security/MessageDigest;");
		jobject obj_md5 = env->CallStaticObjectMethod( class_MessageDigest, tem_method, env->NewStringUTF("md5"));
		if(obj_md5 == NULL){
			SGLOGD("soulgameCheckMD5InPureC() getInstance failed!");
			return false;
		}

		// localMessageDigest.update(localSignature.toByteArray());
		tem_method = env->GetMethodID(class_MessageDigest, "update", "([B)V");// 这个函数的返回值是void，写V
		env->CallVoidMethod(obj_md5, tem_method, obj_sign_byte_array);
		env->DeleteLocalRef(obj_sign_byte_array);

		// localMessageDigest.digest()
		tem_method = env->GetMethodID(class_MessageDigest, "digest", "()[B");
		// 这个是md5以后的byte数组，现在只要将它转换成16进制字符串，就可以和之前的比较了
		jbyteArray obj_array_sign = (jbyteArray)env->CallObjectMethod(obj_md5, tem_method);// jni中有强转类型的概念吗
		env->DeleteLocalRef(obj_md5);
		env->DeleteLocalRef(class_MessageDigest);
		if(obj_array_sign == NULL){
			SGLOGD("soulgameCheckMD5InPureC() digest failed!");
			return false;
		}

		// 尝试用c写一下：http://blog.youkuaiyun.com/pingd/article/details/41945417
		jsize int_array_length = env->GetArrayLength(obj_array_sign);
		jbyte* byte_array_elements = env->GetByteArrayElements(obj_array_sign, NULL);
		char* char_result = (char*) malloc(int_array_length*2+1);// 开始没有+1，在有的情况下会越界产生问题，还是在后面补上\0比较好

		// 将byte数组转换成16进制字符串，发现这里不用强转，jbyte和unsigned char应该字节数是一样的
		ByteToHexStr((unsigned char*)byte_array_elements, char_result, int_array_length);
		*(char_result+int_array_length*2) = '\0';// 在末尾补\0
//		jstring string_result = env->NewStringUTF(char_result);
//		env->DeleteLocalRef(string_result);

		// release
		env->ReleaseByteArrayElements( obj_array_sign, byte_array_elements, JNI_ABORT);
		env->DeleteLocalRef(obj_array_sign);

		//校验
		const char* pWhiteObject;
		bool bIsMD5Right;
		int nIndex = 0;
		int nLen = sizeof(pMD5WhiteList)/4;
		for(nIndex = 0;nIndex<nLen;nIndex++){
			pWhiteObject = pMD5WhiteList[nIndex];
			if( strcmp(char_result,pWhiteObject) == 0 ){
				break;
			}
		}
		if(nIndex<nLen){
			bIsMD5Right = true;
		}else{
			bIsMD5Right = false;
		}

		// 释放指针使用free
		free(char_result);

		SGLOGD("soulgameCheckMD5InPureC() finish!");
		if(bIsMD5Right){
			return true;
		}else{
			return false;
		}
	}