Mcdecryptor

MCDecryptor is a lightweight, open-source utility designed to decrypt legacy stored credentials and session tokens for Minecraft launchers (specifically the old Minecraft Launcher for Windows). It targets the launcher_profiles.json file where Mojang previously stored encrypted access tokens.

⚠️ Ethical Notice: This tool is intended for account recovery (lost passwords) and security research only. Do not use it to access accounts you do not own.

You will see:

[SUCCESS] Lock removed from 47 region files.
[SUCCESS] level.dat sanitized.
[BACKUP] Original saved to MyLockedSurvival.backup

Load the world in Minecraft. The lock message should be gone.

To produce files decryptable by mcdecryptor, you can use a short script to encrypt with AES-GCM, matching the format. Use a random 12-byte nonce, include MAGIC as associated data, and append the 16-byte tag.

MCDeCryptor is a third-party utility tool developed specifically for the Java Edition of Minecraft. Its primary function is to remove encryption or "locks" applied to Minecraft world save files. These locks are typically applied by server-side plugins (such as WorldGuard, Lockette, or GriefPrevention) or by client-side mods that password-protect specific regions or entire dimensions.

Unlike basic file repair tools, MCDeCryptor analyzes the level.dat file and region files (*.mca) to identify proprietary locking mechanisms. It then reverses that encryption, restoring full read/write access to the world.