Oh dear, I guess you have cracked the two caesar cryptos...
This one is more difficult. Although a simple substitution is easily cracked...
Again the characters are limited to A-Z... But I think I can come up with a 256 version again.

Enjoy!

XD SBV OAWENBSD NCY DCH ZOI TVOY SBER WD GTEVIY E OW EWJTVRRVY MVTD KVAA YCIV DCHT RCAHSECI UVD ER XWJIORJIOCJA SBER AESSAV ZBOAAVINV KOR ICS SCC BOTY KOR ES