String Decrypting

Ignition
1

I am trying to figure out a way to decrypt a string, from a ContolLogix PLC. The string has been encrypted using XOR function in Logix5000 and I would like to decrypt the value in Ignition. Anyone have any idea on how I might do this?

2

Presumably there is a multi-byte XOR value associated with this? Or is it based on a CRC or other polynomial?

Whatever it is, you will need to pull the bytes into a byte array, perhaps using a Java ByteBuffer, to apply the algorithm.

Please share the algorithm (and key/seed value) so we can help you.

3

The XOR in the PLC is being performed using the structured text shown below.

for INDEX:= 0 to LoginPassword.LEN do
LoginPassword.DATA[INDEX]:= LoginPassword.DATA[INDEX] XOR PassPhrase.DATA[INDEX];
end_for;

The PassPhrase.Data is as shown below;

image
image956×1536 13.3 KB

Sorry I hope that is enough detail to get the idea.