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I am working on a small cross platform product for Windows and Mac written in C++/Obj-C. I have been asked to implement a licensing module for the same. This task is part of a very ambitious project to introduce licensing for all our products. At the end of it, we will have a complete licensing scheme where we will be able to sell licenses to our customers which support yearly renewals, license levels, etc. My problem is that I do not know the first thing about implementing license checkers. Can any one point me to some how-to's for the same? Are there any open source licensing modules around that I can study?
I use a system of Partial Key Verification (PKV), and I've implemented this in C# with a PHP generator. Google will come up with various hits, explanations, and implementations; but Brandon Staggs wrote a good overview (albeit in Delphi!), here:
http://www.brandonstaggs.com/2007/07/26/implementing-a-partial-serial-number-verification-system-in-delphi/
PKV works by encoding certain information (license type, serial number product, date, etc) in the key along with a hash of the user name, and hashes of the encoded information. Much of the key actually consists of multiple one char hashes. The idea is that you only check a subset of these hashes. The exact subset that issued can be changed over time for some security and to protect against certain kinds of reverse engineering.
I would also encrypt the key to help obfuscate what each char in the license means. Otherwise someone with multiple keys might determine certain char positions mean certain things ("oh, chars 3-4 are the serial number"). This might be a chink in your armour!
Any license system you develop is going to be imperfect. It will be crackable, and if your products are popular, will be cracked. However there's a strong argument that a license system exists to keep the honest people honest, and produce enough hurdles for the slightly dishonest people - but not so many hurdles that it becomes too much of an inconvenience (eg. I'm generally against hardware locking). Those who do hack your system probably weren't going to pay for it anyway.
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My requirement is to seamlessly hot deploy code update to a running service without losing the current status, including collection data. Is there any c++ framework out there I can use to develop such a solution?
You probably should read some research papers on dynamic software updating, e.g. on Kitsune (which you might use)
There is a major issue about updating the call stack (and instances in local variables); read also about continuations; and you might have some special case (if your application is event loop driven like most GUI applications are, you probably want to update the code outside of event handlers).
You certainly should think of dynamic software update very early in your design. Perhaps some terminology and concepts from garbage collection & persistence & serialization techniques are relevant.
Your requirement (to seamlessly hot deploy code update to a running service without losing the current status) is very hard and will need a lot of work (probably years) and is still a difficult & interesting research topic (definitely it is a good PhD subject).
You might want to use your own meta-programming techniques, that is generate most of the relevant C+++ support code by your own code generators.
If you already have a significant code base, you could consider customizing a recent GCC compiler with MELT (e.g. to query the compiler's internal representations and generate some code from them) -but even that means a lot of work-
PS. Coding in something better than C++, like Erlang or Common Lisp, would make your goal less difficult.
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We're running an experiment which will involve collecting data from multiple stations around the world. Each station will be providing HDF5 files with magnetic field measurements in a rate of 1 kHz and some auxiliary data in real time. The latency is going to be a few minutes.
I'm assigned to design this program (in C++, with clients/server model, with server being in linux and clients being cross-platform), and apparently I'll be designing this from scratch. My first concern is not to really do everything from scratch because this will be more error prone and pure wrong, so my question here is: What information/file transfer protocols/libraries should I use so that
The program can live for 10+ years with minimal maintenance
I can have very good support from the community for when I need help.
Since we need something relatively secure, my first thought was libssh (the only cross platform opensource library available out there for ssh), but then after discussing with some pros there I realized that the support there isn't so wonderful because only a few people work with libssh. The pros there hesitated in suggesting OpenSSL, but with OpenSSL I'll have to write my own authentication (apparently, I'm not an expert and that's why I'm asking).
What would you suggest? Please share your vision to whether I should go for OpenSSL, libssh, or something else.
PS: Please, if you're going to start off by saying this question is off-topic, move on and ignore it. Consider being helpful rather than critical.
If you require any additional information, please ask.
I think that OpenSSL might be a good choice.
No you do not have to "write you own authentication" - you just need to generate certificates and keys and put them in the right places - that is all.
I would suggest to look at the examples in <openssl-source-dir>/demos and <openssl-source-dir>/apps to get you started. Reading a book about OpenSSL would also be a good idea - for many other reasons (sometimes not directly related with SSL/TLS).
I hope that helps.
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I have a few C++/DirectX games that I want to start selling from my website. What's the best way to protect my games from being copied/shared? I don't really want to use a classic DRM and the games aren't well suited for the ingame purchase/freemium model.
I don't think revealing the download link after the visitor pays a fee is the correct answer...
If DRM is the only way - even if I don't like it - is there a lightweight DRM solution used by other game developers? (Something with minimal protection)
Thank you!
It's easy if the games are meant to be played online only... perform part of the game calculation only on the server, and use logins. But if you have a single-player mode...
A good "minimal" protection would be to use a hardware fingerprint and a matching HMAC downloaded from the server. When the user moves the game to a different computer, they have to use their credential to generate a new HMAC. The game itself doesn't contain the private key necessary for HMAC generation, only the public key necessary for verification. This will prevent accidental unauthorized copies, and there's very little you can do about skilled crackers anyway.
It's probably a good idea to include sunset logic, in case you shut down your server someday, you don't want your paying customers left with no way to reinstall. The likelihood you'll still be seeing significant income from sales more than 3 years after release is miniscule. You could also release an "update" with the license checks removed at some point in the future if you get tired of checking licenses.
For some extra information on why you don't want to join the arms race, see this answer of mine: The #1 law of software licensing
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I need a C++ library that can store and retrieve time series on demand to stream to client front-ends. I will be storing each component as structure of arrays format. I am currently using MySQL for correctness, but the DB access is starting to get ridiculously slow. I am trying to migrate away from this. Intuitively I can build such a library but it is not my business goal and will take quite a bit of implementation to get working. I am looking for an existing solution that can meet the following requirements:
O(1) lookup scheme
Excellent compression, each component is separated, so there should be plenty of redundancy that can be removed
Scalable to terabytes
(optional: Audit tracking)
Most important: Transactional support. There is going to be BIG data, and I can't have the possibility of a bad run corrupt an entire dataset which will create an unnecessary burden for backups and downtime during restores.
Also checkout TempoDB: http://tempo-db.com I'm a co-founder, and we built the service to solve this problem. We don't have a C++ client yet, but could work with you to develop one.
Take a look at OpenTSDB it's been develop at StumbleUpon by Benoit Sigoure:
http://opentsdb.net/
TeaFiles provide simple and efficient time series storage in flat files, enriched with item metadata and description. They might be a building block of the system you aim for. Currently free open source libraries exist for C++ (github.com/discretelogics/TeaFiles), C# and Python.
I am a founder of discretelogics and we coined this file format to overcome litations flat file time series storage while preserving its unrivaled speed.
Take a look at HDF5. It has a quick lookup scheme, has C, C++, Python interfaces. Has compression. Can get pretty big. Maintains metadata. Doesn't do auditing. You'll need a wrapper to handle multi-user capability.
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Are there any good free C/C++ libraries that enable reading from common devices with filesystems such as UDF, and ISO9660 and extracting files/metadata etc.?
So far all I've been able to find is GNUs libcdio which is promising, and some "Magic UDF" which has so many hits I'm disgusted, pushes other results in Google, and comes with a pretty extreme looking price tag.
Cross-platform support is preferable (personal preference of course), and Windows compatibility is an unfortunate requirement. The less restrictive the license, the better, I have yet to investigate how compatible libcdio's GPLv3 license is.
Note this question is still open, I'll accept another answer if someone locates such a library.
After extensive investigation, I ended up rolling my own solution to perform the operations on UDF that I required. I'm unable to open the source, in all it was about 800 lines of C++. However here are several links which got me through:
The reference standard on which UDF is built
Universal Disk Format specification 2.60
Brief introduction to UDF
Wikipedia Page
UDF Verifier tool (you must sign up for access to this)
A few words of warning: Previous experience implementing ISO9660/ECMA-119 helped me significantly. Knowledge of how block devices operate and interface with the operating system is helpful. Information surrounding the physical layout and separation of sessions is somewhat mythical and difficult to grok.
See: http://www.thefreecountry.com/sourcecode/cpp.shtml
There are a lot of open source library for this but reliability is question.
On Windows You can use Image Mastering API. It comes with Window SDK , Work on both XP & Vista
http://msdn.microsoft.com/en-us/library/aa364806%28VS.85%29.aspx
7-Zip supports extracting files from UDF and ISO disk images, and is mostly LGPL licensed. Specifically, the UDF implementation code appears to be in CPP/7zip/Archive/Udf/UdfIn.cpp.