code: function SHA256(msgBytes) {
    let shaObj = new jsSHA("SHA-256", "HEX");
    let msgHex = byteArray2hexStr(msgBytes);
    shaObj.update(msgHex);
    let hashHex = shaObj.getHash("HEX");
    return hexStr2byteArray(hashHex);
  }
docs: return 32 bytes