Decode Anova Precision Cooker WiFi Packets

fuckuanova.js

const decoder = packetBuf => {
  const bytes = [...packetBuf];
  const { string: command } = bytes.reduce(
    ({ chksum, string }, byte, index) => {
      let newChecksum = chksum;
      let newString = string;
      if (index === bytes.length - 2) {
        newChecksum &= (2 ** 8) - 1; // eslint-disable-line no-bitwise
        if (byte !== newChecksum) {
          throw new Error(`Chksum: FAIL. Read: ${byte} != calc'd: ${chksum}`);
        }
      }
      if (index > 1 && index < bytes.length - 2) {
        newChecksum += byte;
        const n = (index - 1) % 7;
        const newByte = (
          (byte >> n) | // eslint-disable-line no-bitwise
          (
            ( // eslint-disable-line no-bitwise
              byte & ( // eslint-disable-line no-bitwise
                (2 ** n) - 1
              )
            ) <<
            (8 - n)
          )
        );
        newString += String.fromCharCode(newByte);
      }
      return { chksum: newChecksum, string: newString };
    },
    { chksum: 0, string: '' } // eslint-disable-line comma-dangle
  );

  return command;
};

console.log(decoder(Buffer.from('680cce95a3022d1920c6859346a13316', 'hex'))); // get id card