On 2021-Mar-14, Fabien COELHO wrote: > + /*----- > + * Apply 4 rounds of bijective transformations using key updated > + * at each stage: > + * > + * (1) whiten: partial xors on overlapping power-of-2 subsets > + * for instance with v in 0 .. 14 (i.e. with size == 15): > + * if v is in 0 .. 7 do v = (v ^ k) % 8 > + * if v is in 7 .. 14 do v = 14 - ((14-v) ^ k) % 8 > + * note that because of the overlap (here 7), v may be changed > twice. > + * this transformation if bijective because the condition to apply > it > + * is still true after applying it, and xor itself is bijective on a > + * power-of-2 size. > + * > + * (2) scatter: linear modulo > + * v = (v * p + k) % size > + * this transformation is bijective is p & size are prime, which is > + * ensured in the code by the while loop which discards primes when > + * size is a multiple of it. > + * > + */
My main question on this now is, do you have a scholar reference for this algorithm? -- Álvaro Herrera Valdivia, Chile "Someone said that it is at least an order of magnitude more work to do production software than a prototype. I think he is wrong by at least an order of magnitude." (Brian Kernighan)
