My apologies for responding to a very old thread, but i felt like sharing this information here, since it’s hard to find to my knowledge.
The hlunp.exe program is a bit hard to find, but i was able to find it with a google search on some obscure chinese forum, and later found it on a 2004 crack. I’m not sure if i’m permitted to post executables here, so PM me and i’ll send it to ya.
The program does not automatically decrypt the GCFs, the proper keys are required. Turns out they have been publicly posted before multiple times, but they were hard to find without googling at least one of them. The keys can be found on the Half-Life 2 Collector’s Edition page on redump. Simply hover over the “[+]” below the “Contents” text and all the keys for the GCFs should show up.
In order to extract a GCF with the key, you need to give hlunp the proper command. You can see an example below. You could also make a batch/cmd file to extract all of the GCFs automatically.
hlunp -p F:\gcf\halflife_2_base_content.gcf -d F:\hl2 -e \ -k 187D516D65C617EB6FE90FB20211DEC6
What the command does:
- decrypts halflife_2_base_content.gcf in the folder “gcf” on the F:\ drive with the key provided in the command.
- extracts it to the “hl2” folder on the same drive
- (I am not sure what "-e " does, but keep it in there.)
Again, my apologies if this post breaks a rule or two, but hopefully you found it helpful.