Date: October 26, 2025
Subject: Feasibility of "Whitelisting" and DRM for User-Generated Avatars
This paper examines the technical feasibility of implementing "Whitelisting" or Digital Rights Management (DRM) systems within VRChat avatars. Specifically, it analyzes the efficacy of external Open Sound Control (OSC) applications acting as authentication keys, internal PIN systems, and platform-native permissions. The findings indicate that due to the client-side nature of avatar rendering and the lack of logic scripting (Udon) on avatars, true "whitelisting" is technically impossible to secure. The paper concludes that Server-Side Access Control (Private Uploads) remains the only robust method for limiting avatar usage.
As the creator economy within VRChat expands, the demand for restricting avatar access to specific users ("whitelisting") has grown. Creators often seek methods to distribute public avatars while restricting their usage to a list of authorized purchasers or friends. This paper explores the current methods used to attempt this restriction and analyzes their failure points regarding security and user experience.
To understand why whitelisting is difficult, one must understand the architecture of a VRChat avatar.
VRChat allows complex C# scripting (Udon) within Worlds. A World can easily read a user's displayName and grant or deny access to features.
Avatars, however, do not support Udon scripting. They run on the Animator Controller system (Unity's state machine).
- Limitation: An Animator cannot query the VRChat API.
- Limitation: An Animator cannot read the username of the person wearing it.
- Result: An avatar has no self-awareness. It does not know who is wearing it; it only knows what buttons are being pressed. Consequently, a native "if (user == 'MyFriend') return true" check is impossible to implement on the avatar itself.
A popular proposed solution involves using an external application to act as a "Key" for the avatar "Lock."
- The Lock: The avatar is uploaded in a "Locked" state (e.g., mesh disabled or T-posed). A specific boolean parameter (e.g., IsAuthorized) controls the transition to the "Unlocked" state.
- The Key: The user runs an external executable (.exe) on their PC. This program detects VRChat running, verifies the user's identity via the VRChat API/Log files, and sends an OSC signal (/avatar/parameters/IsAuthorized = true) to the client.
While this method functions theoretically, it fails completely as a security measure due to the "Replay Attack" vulnerability.
- Vulnerability A: Parameter Sniffing
VRChat generates a locally stored file for every avatar loaded: parameters.json. Any user can open this text file and view the exact name of the parameter required to unlock the avatar. - Vulnerability B: Signal Spoofing
OSC data is sent over the local network in cleartext. Because the "Key" (the external app) essentially just flips a switch, any generic OSC sender (many of which are free and open-source) can replicate this signal.- Scenario: User A buys your avatar and gets the "Key" app. User A gives the avatar file to User B. User B does not need your app; they simply use a generic OSC debugger to send IsAuthorized = true.
Conclusion on OSC: OSC is designed for communication, not authentication. It cannot be secured against signal replication.
A common "low-tech" alternative is the implementation of a PIN pad within the avatar’s Expressions Menu (Radial Menu).
The user must toggle a specific combination of sub-menus or dials (e.g., entering "1-2-3-4") to transition the Animator state from "Locked" to "Unlocked."
- Social Engineering: The code is easily shared among users.
- Client-Side Ripping: If a malicious user extracts the avatar assets ("ripping"), they have access to the Unity project files. They can simply delete the "Locked" state from the Animator Controller, bypassing the PIN entirely.
- User Experience Friction: Legitimate users are forced to enter a code every time they switch instances or avatars, creating a poor user experience.
Given the failure of client-side locks (OSC and PINs), the only secure method for whitelisting relies on VRChat's server-side authentication.
The creator provides the recipient with the raw Unity Package. The recipient uploads the avatar to their own account with the visibility set to Private.
- Root Level Access: VRChat's servers check the blueprint ID against the User ID before the avatar is even downloaded by other clients.
- No Cloning: Private avatars cannot be cloned by others.
- TOS Compliance: This utilizes the intended permissions system of the platform.
Attempts to "whitelist" VRChat avatars via OSC or PIN systems rely on Security Through Obscurity. They provide the illusion of protection but are easily bypassed by signal spoofing or asset modification.
For creators wishing to restrict avatar usage to a specific group, the only cryptographically secure method is the direct transfer of project files for individual Private Uploads, as this offloads the authentication responsibility to VRChat’s secure servers rather than the vulnerable client-side avatar cache.