Usage: python3 mremoteng_decrypt.py [-f FILE | -s STRING | -rf XML_FILE] [-p CUSTOM_PASSWORD] [-L IS_LEGACY]
If version < v1.75, make sure you specify -L true.
Use for Decrypt mRemoteNG v1.75+ Config.
Usage: java -jar <JAR FILE> <ENCRYPTED TEXT> [Custom Password]
The custom password is in: %appdata/mRemoteNg/<Most recently modified folder>/User.config
org.apache.commons.codec
org.bouncycastle
Carefully check the page.