Simple zip-based DRM system working on Windows
Warren.N Oct 4 2011
We need to protect zip’ed files in our product.
So far, we are thinking of uniquely simple style.
Simply add a small fix to standard zip format.
(Notice: We call such our special
version of zip file ‘zip2’ only here in this document).
First, Zip2 has standard zip format except
for our requirements described here.
Because Zip2 itself need to be read by any Windows zip software in the world.
But a special middleware are not installed in your Windows PC,
you can’t extract all files from Zip2. We need such kind of middleware,
and we’d like to embed this middleware functionarity into our existing product.
Zip2 files must not easily be viewed by anonymous or public user
and then it’s need to be encrypted.
But if only you install a special advertising delivering software(here it called Adware,
our existing product) into your Windows PC, Zip2 can be opend by any 3rd party’s made zip
software(by any Windows freeware, shareware in the world) on your PC.
When zip2 is opened on Windows PCs on which Adware not installed, any file contained
in zip2 still remains in encrypted and zip2 files itself somehow need to indicate
simply something of ‘Please install the software(Adware) to extract all files’ message
to user anyway. (for example, special README message file in non-encrypted
is always enclosed in every zip2 file etc..)
Please mind, once extracted from zip2, files are not need to
be protected anymore (seemingly very loosely protecting).
And zip2 needs to be encrypted in a fixed strong common key in the world.
(it means you don’t have to prepare a unique key for a zip2,
for example, security consideration of per user, per group..and so on)
In this meaing, strict protecting is not required here.
Finally, You provide us with
1. Command program project(s)
(Win32 and Linux binary(exe) and standard C++ source code, makefile or projectfile) that converts normal zip to zip2.
2. Windows program project(s)
(Win32 binary and Win32 C++ source code, makefile or projectfile) that enables zip2 to be opened by any stardard zip client on Windows. Which runtime images are suitable, I have no idea. That depends on you. (Dll, exe, ocx, or combination of that, or needs a special setup, bat, or registry etc etc..)
*About Programming matters
Concrete technical methodology of realizing this specifications
utterly depends on you.
[Code hooking in Windows system]
[url removed, login to view]
Generation task of zip2(converting starndard zip to zip2)
also need to be done on Linux systems.
(Because we’ll later make a web based ASP service(CGI)
of this converting by web-users directly).
Please mind that we’re already using C++(Visual studio 2005) runtime,
so the output of this project must be linked with our existing such modules.
You must provide us with source codes easily being compiled with VC++(VS2005 IDE).
As for general library using, you can only use the followings:
1. Standard C/C++
2. Freeware zip and encryption codes can be used in commercial runtime distribution.
3. Windows 32 bit API and available in Platform SDK for Windows XP or over.
4. Compact library is better as you can enclose all the codes together
in your projects and package in one and provide us easily.
We expect you simple style design and coding for adaptation
of our existing system.
We are using basecamp for project management.
[url removed, login to view]
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