a[0] = secret[i];
for (uint8_t j = 1; j < k; j++)
assert(fread(&a[j], sizeof(uint8_t), 1, random) == 1);
for (uint8_t j = 0; j < n; j++)
D[j][i] = calculateQ(a, k, j+1);
a[0] = secret[i];
for (uint8_t j = 1; j < k; j++)
assert(fread(&a[j], sizeof(uint8_t), 1, random) == 1);
for (uint8_t j = 0; j < n; j++)
D[j][i] = calculateQ(a, k, j+1);