I just did a search on mooncakes which are a cakey thing eaten by chinese during the moon or harvest festival and i found some interesting stuff.   This is from wikipedia …have a read.
Mooncakes were used as a medium by the Ming revolutionaries in their espionage effort to secretly distribute letters in order to overthrow the Mongolian rulers of China in the Yuan dynasty. The idea is said to be conceived by Zhu Yuanzhang (朱元璋) and his advisor Liu Bowen (劉伯溫), who circulated a rumor that a deadly plague was spreading and the only way to prevent it was to eat the special mooncakes. This prompted the quick distribution of the mooncakes, which were used to hide a secret message coordinating the Han Chinese revolt on the 15th day of the eighth lunar month.
Another method of hiding the message was printed in the surface of mooncakes as a simple puzzle or mosaic. In order to read the encrypted message, each of the 4 mooncakes packaged together must be cut into 4 parts each. The 16 pieces of mooncake, must then be pieced together in such a fashion that the secret messages can be read. The pieces of mooncake are then eaten to destroy the message.

As you can see they did some pretty clever stuff….cant say I really like the cakes though.   I got given some by the chinese host family I stayed with . They are very rich and have a flavour that not really like anything else…