安卓逆向||Google Protobuf 序列化請求逆向

谷歌序列化語法文檔 https://colobu.com/2017/03/16/Protobuf3-language-guide/

現在某些app數據加密不僅僅使用常規的加密算法，還會使用一些協議對數據序列化後進行傳輸，最近就遇到一個採用Google 的 Protobuf 對登錄等請求的參數和響應進行了序列化傳輸，頗費了一番功夫。

一、python安裝和實現Protobuf的example

windows系統下載兩個文件protobuf-python-3.5.1.zip和protoc-3.5.1-win32.zip解壓後在protobuf-python-3.5.1\protobuf-3.5.1\python目錄下運行下面命令進行編譯

             python setup.py

             build python setup.py

             install python setup.py test

將protoc.exe放在protobuf-python-3.5.1\protobuf-3.5.1\src下，同時配置環境變量，終端可以使用。前者包含協議序列化數據的一些文件，後者用來用來編譯proto文件。通過一個example，我們看看如何使用。

1、使用 protobuf 首先需要定義一個 examplepb.proto文件，內容如下

syntax = "proto3";
message Student{
    string name = 1;
    int32 id = 2;
    string sex = 3;
     
    message Performance{
        string sbuject = 4;
        string score = 5;
    }
     
    repeated Performance performance = 4;
}

message School{
    string name = 6;
}
 
message Examplepb{
	string age = 1;
    repeated Student student = 2;
	repeated School school = 3;
}

2、examplepb.proto同級目錄下運行命令 protoc examplepb.proto --python_out=./  會生成 examplepb_pb2.py文件

3、新建xulihua.py編寫序列化代碼，fanxuliehua.py 反序列化代碼

# -*- coding: utf-8 -*-
from example_protobuf import examplepb_pb2
data_pb = examplepb_pb2.Examplepb()
student = data_pb.student.add()
school = data_pb.school.add()

data_pb.age = "18"

student.name = "張xxxxxx"
student.id = 10080
student.sex = 'men'
pfm = student.performance.add()
pfm.sbuject = "math"
pfm.score = "98"

school.name = "xxxxx university"

print(data_pb.SerializeToString())
with open("example.bin", 'wb') as f:
    f.write(data_pb.SerializeToString())

# -*- coding: utf-8 -*-
from example_protobuf import examplepb_pb2

data_pb = examplepb_pb2.Examplepb()
student = data_pb.student.add()
school = data_pb.school.add()


def ListExample(data_pb):
    print(data_pb.age)
    for person in data_pb.student:
        print(person.name)
        print(person.id)
        print(person.sex)
        for pf in person.performance:
            print(pf.sbuject)
            print(pf.score)
    for sh in data_pb.school:
        print(sh.name)


with open("example.bin", 'rb') as f:
    data_pb.ParseFromString(f.read())

ListExample(data_pb)

上面這些一個完整的谷歌序列化和反序列化數據的過程，操作完就知道逆向app的谷歌序列化協議關鍵就是proto文件的編寫。未完待續