We need to protect zip files against unauthorized users.
We are planning a simple method that we want to add a small fix into standard zip files.
(Note that we call such special version of zip file as ‘zip2’ in this document.)
1st, zip2 has standard sip format except for our requirement describing below.
Zip2 itself need to be run by any Windows unzip app, but we want to make sure if a special middleware are not installed in a user’s PC, a user can’t extract all files from zip2. We need such kind of middleware, and we need to embed the functionality of the middleware into our existing product. In another way, we want you to make the middleware to be compatible with our existing product.
Zip2 files must not be viewed by an anonymous or a public user, accordingly, they need to be encrypted. But if a user who’s already installed a particular advertising app into his/her PC try to unzip a zip2, it can be unzipped by any 3rd party’s unzip software.
Please note that the particular advertising app is our existing product, we call it ‘Rights App’ in this document.
I show you one idea of mine. A user who never installed “Rights App” can extract a zip2, but he/she can obtain only encrypted files except readme file from extracted zip2. The readme file that wasn’t encrypted will show him/her how to decrypt each files contained in zip2.
It mean that zip2 itself isn’t encrypted, each files contained in zip2 are encrypted. It’s also appropriate for this project. Once the middleware has cognized “Rights App” is installed on user’s PC, it should decrypt encrypted files in zip2 automatically.
Please note that we accept that once encrypted files in zip2 have been decrypted, they don’t need to be protected against pirates anymore. Seemingly very loosely protected, but it’s an ok. And zip2 needs to be encrypted in a fixed conventional strong common key. It means you don’t need to prepare a unique key for this project, for instance, security consideration of per users, per group and so on. Anyhow, we don’t require a strict protecting in this project.
Finally, we need you to provide us with below.
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 these specifications utterly depends on you.
[Code hooking in Windows system]
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Generation task of zip2, converting a standard zip to a zip2, also need to be done on Linux systems. Because we’ll create a web based ASP for this converting process by web-user 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.