KRot is an application designed to do encrypt/decrypt ROT-coded text. Default is ROT13, but you can choose between ROT0 and ROT26 (these two make obviously no sense, but are available).
There is possibility to read/write from/to file. It also has a DCOP interface.
The default language of GUI is English, but there is a Polish translation.
IMPORTANT! Remember to set your prefix to `kde-config --prefix`