Shuffled AES (S-AES) using Python

Implemention of a shuffed version of AES (S-AES), which is similar to AES but with an extra 128-bit key (shuffing key, SK). S-AES operates as AES, but with one modified round. That round is pseudo-randomly selected with SK, and exclusively among the first 9 (encryption) rounds.

The modified round operates as follows:

• In the AddRoundKey step, the SK is used to rotate the bytes of the Round Key used in this round.
• The S-Box used in the SubBytes step is a shuffled variant of the original S-Box wich depends on the SK. The shuffling is done using a variation of the Fisher–Yates shuffle Algorithm.
• In the ShiftRows step, the byte shifts applied to each row are permuted with the SK.
• In the MixColumns step, the SK is used to add an offset to the index used to select the column in one of the matrices.

If a SK is not used, the program operates with the normal AES.

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The required files are:

• SAES.py (library)
• encrypt.py
• decrypt.py
• speed.sh

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To encrypt something, use:

echo some_plain | python3 encrypt.py [--timeit] key [skey]

To decrypt something, use:

echo some_cipher | python3 decrypt.py [--timeit] key [skey]

To test the performance (will take long), run:

chmod +x speed.sh
./speed.sh > times/overall_100k_best_times.txt

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To check the profiler results (need to install snakeviz), run:

snakeviz profiler/<profiler_file>

To run any test, do:

python3 -m venv venv
source venv/bin/activate
pip3 install -r requirements.txt