Added hash-mode: Citrix NetScaler (PBKDF2-HMAC-SHA256)

[stumblebot]

Here's code for a new hash-mode. It handles Citrix NetScaler's most recent (since 13.1) local system user password hashing scheme, PBKDF2-HMAC-SHA256 with 2500 rounds.

This is an extension of work done by my colleague @dru1d-foofus and I. You can find some additional background and documentation : here

As a quick summary, this is basically a re-worked implementation of the existing hash mode 10900. The kernel is essentially unchanged and the module has been modified to reflect the the different token parsing scheme and input type (hex instead of base64). I've also made some changes to buffer sizes to reflect the static length of the salt.

I've tested this on a handful of manually generated hashes pulled from a Citrix NetScaler appliance and it works as expected on an OpenCL cpu-based platform, as well as a CUDA-driven gpu-based platform.

Thanks!

[stumblebot]

Reviewing some other modules that also use PBKDF2-HMAC-SHA256, I can see that creating a 'new' kernel for this is redundant.

The only reason I could see to actually implement and use a new kernel would be to take advantage of the fixed length of the salt/digest values but in my (admittedly amateur) attempts to make these changes I didn't see any performance benefits.

I'll push a change to use the existing 10900 kernel instead of adding a new one.

[stumblebot]

Consolidated this to use the existing PBKDF2-HMAC-SHA256 kernel, 10900