By now you've no doubt heard the story of the pigeon discovered in England with a World War II message on its leg that can't be read because it's in code. (If not, check this story or this one.)
The media is having a lot of fun with it, but along the way is sharing more than a few misconceptions about coding and encryption. These include the 'reasons' the message can't be decrypted:
One is with a so-called one-time pad where a random "key" is applied to a message. If the key is truly random and known only to sender and recipient, the code can be unbreakable.
That's why we're still using pigeon encryption for all our important messages . . .
Footnote: The British awarded the Dickin Medal to animals, including carrier pigeons, that served with special distinction during the war. Honored birds were credited with delivering messages from Dieppe and Normandy, and also with delivering information about trapped units. The birds were also used, occasionally, to send some "spy" information from behind enemy lines, though that doesn't actually seem to apply here.