fips202 keccak_absorb does not absorb properly

[bwesterb]

The current implementation is flawed:

pub(crate) fn keccak_absorb(
  s: &mut[u64], 
  mut pos: usize, 
  r: usize, 
  input: &[u8], 
  mut inlen: usize
) -> usize
{
  let mut idx = 0usize;
  while pos+inlen >= r {
    for i in pos..r {
      s[i/8] ^= (input[idx] as u64) << 8 * (i%8);
      idx += 1;
    }
    inlen -= r-pos;
    keccakf1600_statepermute(s);
    pos = 0;
  }
  let new_pos = pos+inlen;
  for i in pos..new_pos {
    s[i/8] ^= (input[idx] as u64) << 8 * (i%8);
  }
  new_pos
}

Note that idx is not incremented in the final loop.

[bwesterb]

As far as I can tell keccak_absorb isn't actually used.