Differential Cryptanalysis Example

This Excel Spreadsheet contains a working example of a simple Differential Cryptanalysis attack against a substitution-permutation network (SPN) with 16-bit blocks and 4-bit S-boxes.

Implemented as a Visual Basic macro for use in Excel 2007 or newer.

The Excel workbook contains two sheets. The first, "How it works", is designed for use in a lecture, in order to illustrate how Differential Cryptanalysis works. The S-box can be edited, and the illustrated algorithm steps will reflect the new S-box.

The second tab is a demonstration of an attack. You can edit the S-box, permutation, and key schedule. The macros will then perform the attack and show the most-likely value of part of key K5.

The textbook referenced in the spreadsheet is Cryptography Theory and Practice 3rd ed. by Douglas Stinson.

Screenshots

Interactive Illustration of the Algorithm:

Demonstration of an attack:

License

Copyright (c) 2011 Braden MacDonald

This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software.

Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.

2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.

3. This notice may not be removed or altered from any source distribution.