Equivalence Classes in AES (G22b)
This talk will reveal original research concerning the examination of the AES cryptographic algorithm which provides a new method of cryptanalysis of AES. This talk will:
a) Define the concept of an equivalence class in AES in terms of the XOR of bytes.
b) Show how each round sub-function can be replaced with a corresponding operation on equivalence classes: SubBytes, ShiftRows, MixColumns, AddRoundKey.
c) Show when using the all zero key, there is a trivial property of equivalence classes that passes through all of the rounds of AES, providing the plaintext that is input, has this property. This property is fully detectable in ciphertext.
d) Show that if the key schedule had the same equivalence class property, then, the same property still passes through all of the rounds of AES. We indicate whether such a property is possible or not in the real key schedule.
e) Provide deeper results, concerning the equivalence classes of AES which indicate that the algorithm may be weaker than currently assumed.