Hot answers tagged algorithm-design
You have clarified the question as asking about whether replacing ShiftRows with a random byte permutation would strengthen AES against differential attacks. It would not. ShiftRows and MixColumns were carefully selected to work in tandem, such that every byte affects every other byte in the state within just two rounds. MixColumns ensures that every ...
I assume that you mean the S-box. The answer is NO! Randomly chosen S-boxes are not good choices for differential and linear cryptanalysis. When Biham and Shamir presented differential attacks on DES, one of the things that they showed was that if you replace the S-boxes in DES with randomly chosen ones, then the differential attack becomes much more ...
Many properties of boolean functions are used in stream and block cipher design, e.g., when they are used as filtering and combining functions. Some important examples are: Nonlinearity (minimal Hamming distance of the truth table of the boolean function from affine functions), must be high for resisting linear/affine approximation attacks. Correlation ...
This is homework, and so I won't give you the answer outright; I will give hints: Hint 1: how could you efficiently generate a random pair $x_1, y_1$ with $x_1^e = y_1$, without resorting to the Oracle? Hint 2: how could you use the above observation to accelerate your algorithm?
Shamir secret sharing scheme is one of the examples.
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