I've noticed that some characters in Q3A are always accepted as the right cd-key. So I built a small CMD script for Windows operating systems over v5.1 (XP and above).
Message: "The cd key appears to be valid, thank you". You see: IT WORKS!
Run 'q3key.cmd'. The 'q3key' file is created automatically. An existing file is not overwritten. Copy it to your 'baseq3' directory. The cd-key is also automatically copied to the clipboard. If the q3key file is not needed, comment out or remove the 49th line.
The script can be used to create up to 16^16 different keys and it creates only a random composition of the characters listed above.