Note: This is not mean't to be fast. As I work I'll try to optimize to the best of my ability but this is above all a POC implementation of dynamic S-Boxes! (It is MUCH faster under PyPy for larger plaintext sizes! and slightly slower for smaller ones... see the speed tests section)
A pure python3(/2.7) implementation of the Rijndael cipher (AES) based on Brandon Sterne's python2.5 implementation that additionally implements modifications to the AES Cipher suggested in various academic papers to dynamically generate S-Boxes from the cipher key instead of using the fixed Rijndael S-Box.
I am using the Hosseinkhani-Javadi method to generate the S-Box, although using all 256 bits of the key instead of just the first 128 to perform two rounds in a similar fashion to a block cipher.
One possible attack method would be to generate all possible S-Boxes from all possible 256 bit AES keys and apply them during the subBytes step as suggested by Hosseikhani and Javadi, but the number of possible S-Boxes is somewhere around 10 to the power of 38, factorial ((10^38)!) choices for 128-bits of key. By mixing a full 256 bit key with itself and using each 128 bit half of the key for two rounds of the sboxRound function we increase the number of possible S-Boxes to 2^256.
test_key = "f4eba54dab7b4cdcb34f13689beea128acdc8960c8ec4c929d0c9f85d2fa5c22" # 256-bit (64 character) hex key
int_test_key = dAES.hexToKey(test_key)
plain = "blahblahblahblah i like really weirdly secure AES techniques!"
cipher = dAES.encrypt(plain, int_test_key)
decryptedPlain = dAES.decrypt(cipher, int_test_key)
Over ~650,000 iterations
These mean speeds are based on running the speed_tests function from dAES-tests.py on my random ol' server (so take them with a grain of salt...) Each time is a mean time over 100 iterations with each different plaintext size [32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288] (Also note that OFB encryption and decryption cannot be parallelized, so yeah.)
rolands@kamaji:~/utils/dAES$ python dAES-tests.py
mean encryption speed for 32 character string: 0.00114s
mean decryption speed for 32 character string: 0.00112s
mean encryption speed for 64 character string: 0.001855s
mean decryption speed for 64 character string: 0.00185s
mean encryption speed for 128 character string: 0.003317s
mean decryption speed for 128 character string: 0.003313s
mean encryption speed for 256 character string: 0.006288s
mean decryption speed for 256 character string: 0.006584s
mean encryption speed for 512 character string: 0.012169s
mean decryption speed for 512 character string: 0.010772s
mean encryption speed for 1024 character string: 0.020697s
mean decryption speed for 1024 character string: 0.020661s
mean encryption speed for 2048 character string: 0.040693s
mean decryption speed for 2048 character string: 0.040577s
mean encryption speed for 4096 character string: 0.085646s
mean decryption speed for 4096 character string: 0.083073s
mean encryption speed for 8192 character string: 0.164645s
mean decryption speed for 8192 character string: 0.1622s
mean encryption speed for 16384 character string: 0.324669s
mean decryption speed for 16384 character string: 0.326186s
mean encryption speed for 32768 character string: 0.649447s
mean decryption speed for 32768 character string: 0.6676s
mean encryption speed for 65536 character string: 1.331664s
mean decryption speed for 65536 character string: 1.323691s
mean encryption speed for 131072 character string: 2.65424s
mean decryption speed for 131072 character string: 2.640893s
mean encryption speed for 262144 character string: 5.243996s
mean decryption speed for 262144 character string: 5.227484s
mean encryption speed for 524288 character string: 10.681648s
mean decryption speed for 524288 character string: 10.597086s
rolands@kamaji:~/utils/dAES$ pypy dAES-tests.py
mean encryption speed for 32 character string: 0.002973s
mean decryption speed for 32 character string: 0.001345s
mean encryption speed for 64 character string: 0.001117s
mean decryption speed for 64 character string: 0.000838s
mean encryption speed for 128 character string: 0.000915s
mean decryption speed for 128 character string: 0.00093s
mean encryption speed for 256 character string: 0.001026s
mean decryption speed for 256 character string: 0.00089s
mean encryption speed for 512 character string: 0.001667s
mean decryption speed for 512 character string: 0.001631s
mean encryption speed for 1024 character string: 0.003121s
mean decryption speed for 1024 character string: 0.003104s
mean encryption speed for 2048 character string: 0.005381s
mean decryption speed for 2048 character string: 0.005349s
mean encryption speed for 4096 character string: 0.010716s
mean decryption speed for 4096 character string: 0.011091s
mean encryption speed for 8192 character string: 0.021394s
mean decryption speed for 8192 character string: 0.021311s
mean encryption speed for 16384 character string: 0.042622s
mean decryption speed for 16384 character string: 0.044081s
mean encryption speed for 32768 character string: 0.085557s
mean decryption speed for 32768 character string: 0.086141s
mean encryption speed for 65536 character string: 0.177523s
mean decryption speed for 65536 character string: 0.175356s
mean encryption speed for 131072 character string: 0.338576s
mean decryption speed for 131072 character string: 0.337783s
mean encryption speed for 262144 character string: 0.693953s
mean decryption speed for 262144 character string: 0.677284s
mean encryption speed for 524288 character string: 1.354397s
mean decryption speed for 524288 character string: 1.360687s
rolands@kamaji:~/utils/dAES$ lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 24
On-line CPU(s) list: 0-23
Thread(s) per core: 2
Core(s) per socket: 6
Socket(s): 2
NUMA node(s): 2
Vendor ID: GenuineIntel
CPU family: 6
Model: 44
Stepping: 2
CPU MHz: 1600.000
BogoMIPS: 5331.76
Virtualization: VT-x
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 12288K
NUMA node0 CPU(s): 0,2,4,6,8,10,12,14,16,18,20,22
NUMA node1 CPU(s): 1,3,5,7,9,11,13,15,17,19,21,23
- Using Cipher Key to Generate Dynamic S-Box in AES Cipher System by R. Hosseinkhani and H. Haj Seyyed Javadi
- IMPLEMENTATION OF STRONGER AES BY USING DYNAMIC S-BOX DEPENDENT OF MASTER KEY by S. Arrag, A. Hamdoun, A, Tragha, and S. Eddine Khamlich
- Generation of AES Key Dependent S-Boxes using RC4 Algorithm by Abd-ElGhafar, A. Rohiem, A. Diaa, and F. Mohammed
- Dynamic Substitution Box