feistel.go

// feistel network test
// currently doesn't work as expected.
// the idea is to use variable return
// function to make branchment instead
// of traditional datastructure.

package main

import "fmt"

func f(k int64, r int64) int64 {
	ret := (r ^ k << 1)
	fmt.Printf("f: %0.2x\n", ret)
	return ret
}

func block(k int64, l int64, r int64) (int64, int64) {
	fmt.Printf("%0.2x %0.2x %0.2x\n", k, l, r)
	lret := r
	rret := f(k, r) ^ l
	fmt.Printf("%0.2x %0.2x %0.2x\n", k, lret, rret)
	return lret, rret
}

func test() {
	var i int64
	var l int64
	var r int64
	l = 12
	r = 13
	for i = 0; i < 24; i++ {
		l, r = block(i, l, r)
	}
	fmt.Printf("__ %0.2x %0.2x\n", l, r)

	ll := l
	rr := r
	fmt.Println()
	for i = 23; i >= 0; i-- {
		ll, rr = block(i, ll, rr)
	}
	fmt.Printf("__ %0.2x %0.2x\n", ll, rr)
}

func main() {
  test() 
}