If you do not know the encryption key of your mod, it's probably x9Ke0BY7 (the default for HL2DM). You should encrypt your script files so they can not easily be changed by users.
Changing Encrypted Weapon Scripts
To have the ability to change the weapon scripts, a mod user would have to delete the .ctx files and create the .txt files from scratch. This makes your mod more resistant to change, which means hosted servers won't as likely have changed the weapon scripts.
The source code of a Steam dependent version of VICE is available in the Source SDK.
There is a version of vice that runs independent from steam available here: Using Vice without Steam
You can download the vice standalone application with wildcard support from here.
Most users who try Steam will get a problematic SteamAppId error. This is due to Steam filesystem update inconsistancy. It stripped one word from the gameinfo.txt and didn't notify anyone. In order to use these Steam applications you must go to the root folder of your mod or the game you want to modify, and change ToolsAppID to AppID. This will allow you to use both versions of vice and a few more programs like mdldecompiler. You must also make sure that your mod or game is selected in vconfig. If you edit your mod's gameinfo file and have Half-Life 2 selected in vconfig you will not be doing much.
If you are decrypting Valve games and not your own mods, then you will have to make this change each time you want to use vice or any other applications that give the same message. For each time you run say, Day of Defeat: Source, it creates a new GameInfo.txt file that still include Tools.
Execute this in the command prompt to make the .ctx files:
"[Source SDK Bin]\vice.exe" -x .ctx -k [Key: x9Ke0BY7 by default for HL2DM mods] [.txt filename (Use * for wildcard)]
Changing the Key for Your Mod
- You must change the returned string in the function "GetEncryptionKey" in the gamerules. The new encryption key must be eight characters long. This encryption key should be used when running VICE.
Decrypting Script Files
- If you happen to lose your .txt files and you only have their .ctx files and your mod's encryption key, you can run VICE to decrypt also:
"[Source SDK Bin]\vice.exe" -d -x .txt -k [Key: x9Ke0BY7 by default for HL2DM mods] [.ctx filename (Use * for wildcard)]