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Equal corresponding elements of the permutations, resulting from change of key

 

 
Test 1. 2^33.2 pairs of 128-bit, 2^33.2 pairs of 256-bit and 2^33.2 pairs of 512-bit keys, differing by each possible value in each possible (one at a time) position of the key, were used to generate 256-element permutations with the VMPC Key Scheduling Algorithm.

Test 2. 2^33.2 pairs of 128-bit, 2^33.2 pairs of 256-bit and 2^33.2 pairs of 512-bit keys, differing by each possible value in the last position of the key (the position of the key which is last to be used for the first time by the KSA), were used to generate 256-element permutations with the VMPC Key Scheduling Algorithm.

In Test 1 and in Test 2 - frequencies of occurrence of situations, where the elements in each of the corresponding positions of the permutations are equal, were measured

Let P1(X) denote X-th element of the permutation generated from one key and P2(X) denote X-th element the permutation generated from the changed key.

Situations where the corresponding elements of the permutations are equal (P1(X)=P2(X)) should occur with probability 1/256 - for each of the positions (X) of the permutations.

With consideration of the fact that 256 variables were tested - the measured frequencies of occurrence of these situations for Test 1 and Test 2 showed no statistically significant deviation from their expected values.


by Bartosz Zoltak




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