Files got encrypted with DERP extension in Help, my files are encrypted! Posted November 1, 2019 · Report reply Sir I tried to decrypt the file with latest STOP djvu tool and got the below message. Please advice how to Decrypt the the file. Starting... File: D:\AIMSR\backupsettings.conf.derp Error: Unable to decrypt file with ID: lTKcWFGiMexfflgVI8Wexen2feaqqthjrJKGlIdv Finished!