import base64

#Decode
xored = ‘KD4sPjsyNjE=’
plain = ”.join([chr(ord(c)^ord(‘_’)) for c in base64.b64decode(xored)])
#Encode
enocoded = base64.b64encode(”.join([chr(ord(c)^ord(‘_’)) for c in plain]))

ref:

https://idmdepot.com/How_To/IBM_WebSphere_Application_Server_How_To.html