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Integrity Check: VerifySignatures

Arma 3 trusts the client by default. To prevent malicious actors from joining your server with modified PBO files (e.g., a “One Hit Kill” pistol modification or a “Transparent Walls” foliage mod), you must enforce strict signature verification. This ensures every file on the client matches the signed files on the server.
Reading TimeDifficultyLast Updated
5 minutesIntermediateJanuary 2026

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Enabling Enforcement

In your server.cfg, you must set: 
verifySignatures = 2;
  • 0: Off. Anyone can join with any files. (Security Risk).
  • 2: V2 Signature Check. Strict enforcement. (Industry Standard).

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The Key System (/keys/)

For a mod to pass the V2 check, the server must possess its Public Key (.bikey).
  1. Locate Key: Open your mod folder on your PC (e.g., @ACE3). Look for a folder named keys or serverkeys.
  2. Transfer: View the .bikey file (e.g., ace3.bikey).
  3. Upload: Upload this file to the root /keys/ directory on your game server.
Result: The server now “Trusts” any PBO signed by ace3.bikey.

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Troubleshooting “Signature Mismatch”

If players are kicked immediately upon joining with a “Signature Mismatch” error, it means one of two things:
  1. Missing Key: You forgot to upload the .bikey file for a mod you are running.
  2. Corrupt File: The player’s local mod file is outdated or modified. Tell them to “Verify Integrity” or “Repair Mod” in the Arma 3 Launcher.

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Support Channels

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Last Updated: January 2026 | Arma 3: Perimeter secured.