Kid Krypto

Cryptographic ideas and protocols that are accessible to children are described, and the case is made that cryptography can provide an excellent context and motivation for fundamental ideas of mathematics and computer science in the school curriculum, and in other venues such as children's science museums. It is pointed out that we may all be doing "Kid Krypto" unawares. Crayon-technology cryptosystems can be a source of interesting research problems; a number of these are described.