ValleyAuth

ValleyAuth is a lightweight authentication, identity, and player-data management plugin for modern Paper servers.

It lets you run an offline-mode server while automatically recognizing legitimate Mojang accounts. Premium players join seamlessly without passwords, while unauthenticated Java players use a traditional register/login system.

This plugin is a simple and more convenient alternative to the regular FastLogin + Authme setup most servers use.

Key Features

• Hybrid Authentication: Authenticates valid Mojang accounts automatically via standard encryption handshakes. (Even if server is in offline mode!)
• Seamless Premium Support: Premium Java players bypass /register and /login completely.
• Name-Change Resilient: Premium identity is tied to Mojang UUIDs, keeping player data safe across username changes.
• Deterministic Offline Accounts: Unauthenticated accounts are assigned consistent, deterministic UUIDs for stable player data.
• First-Class Crossplay Support: Built-in compatibility for GeyserMC and Floodgate setups.

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Identity Breakdown

Prefix and identifiers for bedrock players are controlled by Geyser MC and Floodgate, ValleyAuth requires Floodgate to recognize these identifiers for each user.

ValleyAuth routes connecting players into three distinct identity types:

Identity Type	Username Prefix	UUID Source	Requires /login
Premium	(None)	Mojang Session	❌ No
Bedrock	.	Floodgate API	❌ No
Offline	-	ValleyAuth (Deterministic)	✅ Yes

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Requirements

• Server: Paper 1.21 or higher
• Java Version: Java 21+
• Dependencies:
  • packetevents v2.13.0+ (Required for forced authentication flow)
  • ProtocolLib v5.4.0+ (Optional fallback)
  • Floodgate (Optional, required only for GeyserMC crossplay)

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Commands

• /register <password> <password> – Register a new Offline account.
• /login <password> – Log in to an existing Offline account.

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Configuration & Mechanics

ValleyAuth automatically adapts based on your server.properties setup:

• online-mode=true – ValleyAuth stands down and allows vanilla authentication to take over.
• online-mode=false – ValleyAuth enforces forced Mojang verification for incoming non-Floodgate connections.

GeyserMC / Floodgate Crossplay Notes

If you run a crossplay server using GeyserMC, Floodgate is required.

Because Bedrock clients cannot perform the Java encryption handshake, ValleyAuth relies on Floodgate to identify Bedrock connections and grant them a stable . prefix identity without locking them in a verification loop.