function generateSignature(...signingData) {
 const raw = web3Util.soliditySha3(...signingData);
 const salted = ethUtil.hashPersonalMessage(ethUtil.toBuffer(raw));
 const {
   v,
   r,
   s
 } = lodash.mapValues(ethUtil.ecsign(salted, ethUtil.toBuffer('0x'+user.pk.trim())), (value, key) => key === 'v' ? value : ethUtil.bufferToHex(value));
 //console.log("Signature complete! ", v, r, s);
 return {v: v, r: r, s: s};
}