round.h

#ifndef ROUND_H_
#define ROUND_H_

#include "ascon.h"
#include "printstate.h"

static inline uint64_t ROR64(uint64_t x, int n) {
  return (x << (64 - n)) | (x >> n);
}

static inline void ROUND(state_t* s, uint8_t C) {
  state_t t;
  /* addition of round constant */
  s->x2 ^= C;
  /* substitution layer */
  s->x0 ^= s->x4;
  s->x4 ^= s->x3;
  s->x2 ^= s->x1;
  /* start of keccak s-box */
  t.x0 = s->x0 ^ (~s->x1 & s->x2);
  t.x1 = s->x1 ^ (~s->x2 & s->x3);
  t.x2 = s->x2 ^ (~s->x3 & s->x4);
  t.x3 = s->x3 ^ (~s->x4 & s->x0);
  t.x4 = s->x4 ^ (~s->x0 & s->x1);
  /* end of keccak s-box */
  t.x1 ^= t.x0;
  t.x0 ^= t.x4;
  t.x3 ^= t.x2;
  t.x2 = ~t.x2;
  /* printstate(" substitution layer", &t); */
  /* linear diffusion layer */
  s->x0 = t.x0 ^ ROR64(t.x0, 19) ^ ROR64(t.x0, 28);
  s->x1 = t.x1 ^ ROR64(t.x1, 61) ^ ROR64(t.x1, 39);
  s->x2 = t.x2 ^ ROR64(t.x2, 1) ^ ROR64(t.x2, 6);
  s->x3 = t.x3 ^ ROR64(t.x3, 10) ^ ROR64(t.x3, 17);
  s->x4 = t.x4 ^ ROR64(t.x4, 7) ^ ROR64(t.x4, 41);
  printstate(" round output", s);
}

#endif /* ROUND_H_ */