We intercepted following message:

28 c0 65 a3 f9 60 05 a4 09 d9 b0 01 20 0f 15 54 87 10

It is encrypted using a 4 byte key with the Kassandra cloud encryption

Can you crack it?

You find the kassandra clound encyption service here:

188.40.147.119 9001

This flag does not have a SIGINT_ prefix!