Diffusion in SDES

This applet demonstrates how the round function of S-DES works. It is also demonstrates the diffusion property. Any time a magenta bit is used as input, any output bits that are affected by it will also be magenta. One bit starts out magenta, and by the end of the round function five are magenta. This diffusion comes from the Expansion/Permutation and the S-boxes. The input to the round function is the eight bits at the very top.

Click on the applet to begin. The applet may take a minute to load.

Animation engine by Eric Fikus, content and animation code modifications by Jedidiah Crandall

For a good background reading on S-DES and diffusion see Chapter 3 of Cryptography and Network Security: Principles and Practice by William Stallings

This was created as part of the Cryptography Module of NSF Award No. 0113627: "Increasing Security Expertise in Aviation-oriented Computing Education: A Modular Approach", at Embry-Riddle Aeronautical University in Prescott, Arizona.

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Last update: August 1, 2002