Demitasse: A “Small” Version of the Tiny Encryption Algorithm and Its Use in a Classroom Setting

Abstract

This article describes Demitasse, a cipher that is intended to be used by inexperienced students in a classroom setting. The cipher is based on the Tiny Encryption Algorithm, but the parameters have been reduced in order to allow the students to operate the cipher with paper and pencil rather than a computer. Nevertheless, students using the cipher should gain some understanding into the inner workings of a modern computer cipher. An example of the use of Demitasse in the classroom is also discussed.

Keywords:

• course development
• teaching cryptography
• Tiny Encryption Algorithm
• toy ciphers

Acknowledgments

My thanks to the anonymous reviewer for helpful suggestions and references.

Notes

¹Incidentally, the moral of this story is not so much to avoid ciphers with equivalent keys; the moral is really “do your homework.” the TEA was never designed to be used in a hash function, and in fact, experts had warned in 1996 that a hash function based on the TEA would be insecure [8].

Additional information

Notes on contributors

Joshua Holden

Joshua Holden is currently an associate professor in the Mathematics Department of Rose-Hulman Institute of Technology, an undergraduate engineering college in Indiana. He received his PhD from Brown University in 1998 and held postdoctoral positions at the University of Massachusetts at Amherst and Duke University. His research interests are in computational and algebraic number theory, cryptography, and the application of graph theory to fiber arts. His teaching interests include the use of technology in teaching and the teaching of mathematics to computer science majors, as well as the use of historically informed pedagogy. His non-mathematical interests used to include fiber arts, but that now seems to be a mathematical interest. Still largely in the non-mathematical category are his interests in science fiction and music, both classical and contemporary.