C++ get Processor ID
I had a similar problem lately and I did the following. First I gained some unique system identification values:
GetVolumeInformation for HDD serial number
GetComputerName (this of course is not unique, but our system was using the computer names to identify clients on a LAN, so it was good for me)
__cpuid (and specifically the PSN - processor serial number field)
GetAdaptersInfo for MAC addresses
I took these values and combined them in an arbitrary but deterministic way (read update below!) (adding, xoring, dividing and keeping the remainder etc.). Iterate over the values as if they were strings and be creative. In the end, you will get a byte literal which you can transform to the ASCII range of letters and numbers to get a unique, "readable" code that doesn't look like noise.
Another approach can be simply concatenating these values and then "cover them up" with xoring something over them (and maybe transforming to letters again).
I'm saying it's unique, because at least one of the inputs is supposed to be unique (the MAC address). Of course you need some understanding of number theory to not blew away this uniqueness, but it should be good enough anyway.
Important update: Since this post I learned a few things about cryptography, and I'm on the opinion that making up an arbitrary combination (essentially your own hash) is almost certainly a bad idea. Hash functions used in practice are constructed to be well-behaved (as in low probability of collisions) and to be hard to break (the ability construct a value that has the same hash value as another). Constructing such a function is a very hard computer science problem and unless you are qualified, you shouldn't attempt. The correct approach for this is to concatenate whatever information you can collect about the hardware (i.e. the ones I listed in the post) and use a cryptographic hash or digital signature to get a verifiable and secure output. Do not implement the cryptographic algorithms yourself either; there are lots of vulnerability pitfalls that take lots of knowledge to avoid. Use a well-known and trusted library for the implementation of the algorithms.
If you're using Visual Studio, Microsoft provides the __cpuid instrinsic in the <intrin.h> header. Example on the linked msdn site.
Hm...
There are special libraries to generate unique ID based on the hardware installed (so for the specified computer this ID always be the same). Most of them takes motherboard ID + HDD ID + CPU ID and mix these values.
Whe reinvent the wheel? Why not to use these libraries? Any serious reason?