Experts at intelligence agency GCHQ have asked for help in de-coding a message found attached to a pigeon leg, thought to date back to WWII.
The dead bird was found in a chimney in Surrey a few weeks ago.
But without more information, the code may never be cracked, according to the BBC's security correspondent Gordon Corera.
The code is as follows:
AOAKN HVPKD FNFJW YIDDC
RQXSR DJHFP GOVFN MIAPX
PABUZ WYYNP CMPNW HJRZH
NLXKG MEMKK ONOIB AKEEQ
WAOTA RBQRH DJOFM TPZEH
LKXGH RGGHT JRZCQ FNKTQ
KLDTS FQIRW AOAKN 27 1525/6
BBC News - WWII code 'may never be cracked'