rai-pow.js

function genPow(hash, timeout) {
  timeout = timeout || 15000000;
  const start = Date.now();
  const hashBytes = hex_uint8(hash);
  let i=0;
  while(Date.now() - start < timeout) {
    const workBytes = nacl.randomBytes(8);
    for(let j=0;j<256;j++) {
      workBytes[7] = j;

      const context = blake2bInit(8, null);
      blake2bUpdate(context, workBytes.reverse());
      blake2bUpdate(context, hashBytes);
      const score = blake2bFinal(context);
      i++;
      if(score[7] == 0xff && score[6] == 0xff && score[5] == 0xff && score[4] > 0xc0) {
        console.log(i, Date.now() -start);
        return workBytes;
      }
    }
  }
  console.log(i, Date.now() -start);
}