Example Code for Message Signing Added (#968)
Added an example java script which demonstrates the following - How to sign a message using Ethereum account - How to find the address using which the message was signed
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Susmit
Fabian Vogelsteller
parent
7df9c539c3
commit
11ca4d0da4
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/**
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* This utility module helps to demonstrate following features
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* a. Signing a message by an Ethereum user
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* b. Finding the account address using which the message was signed
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*/
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var Web3 = require('../index.js');
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var ethURL = "";
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var defaultAc = "";
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var defaultAcPWD="";
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var signatureContractCodeReadable="\n\tcontract SignatureVerifier {\n\t\tfunction verify( bytes32 hash, uint8 v, bytes32 r, bytes32 s) \n"+
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"\t\tconstant returns(address returnAddress) {\n \t\t\treturnAddress = ecrecover(hash, v, r, s);\n\t\t}\n\t}\n\n";
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var sigContractInstance = null;
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var sigContractAddress= "";
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var sigContractInstance = null;
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var strAbi='[{"constant":true,"inputs":[{"name":"hash","type":"bytes32"},{"name":"v","type":"uint8"},{"name":"r","type":"bytes32"},{"name":"s","type":"bytes32"}],"name":"verify","outputs":[{"name":"returnAddress","type":"address"}],"payable":false,"type":"function"}]';
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var signMessage="";
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var ethWeb3 = null;
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function setContractAddress(conAddress){
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sigContractAddress = conAddress;
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}
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function setAccount(act){
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defaultAc = act;
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}
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function setPassword(pwd){
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defaultAcPWD = pwd;
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}
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function setEthereumURL(url){
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ethURL = url;
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}
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function setMessage(msg){
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signMessage = msg;
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}
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function initializeEthereumConnection(){
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if(ethWeb3!=null && ethWeb3.isConnected()==true) {
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return true;
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}
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ethWeb3 = new Web3(new Web3.providers.HttpProvider(ethURL));
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if(ethWeb3.isConnected()==true){
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if(defaultAc==''){
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defaultAc=ethWeb3.eth.accounts[1];
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}
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return true;
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}
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return false;
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}
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function unlockAccount(acAddress){
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if(acAddress!=undefined && acAddress!=null){
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var state=ethWeb3.personal.unlockAccount(defaultAc, defaultAcPWD, 100);
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return state;
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}
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return false;
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}
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function initializeContract(){
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initializeEthereumConnection();
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if(ethWeb3.isConnected()==false){
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return;
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}
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var abi = JSON.parse(strAbi);
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var contract = ethWeb3.eth.contract(abi);
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sigContractInstance = contract.at(sigContractAddress)
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}
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function signMessage(message){
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initializeEthereumConnection();
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if(ethWeb3.isConnected()==false){
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return false;
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}
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var state=unlockAccount(defaultAc);
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const msg = new Buffer(message);
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const sig = ethWeb3.eth.sign(defaultAc, '0x' + msg.toString('hex'));
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return sig;
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}
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function verifySignedByAc(message, sig){
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initializeEthereumConnection();
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if(ethWeb3.isConnected()==false){
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return false;
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}
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initializeContract();
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const res = splitSig(sig);
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// Unfortunately Geth client adds this line to the message as a prefix while signing
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// So while finding who signed it we need to prefix this part
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const prefix = new Buffer("\x19Ethereum Signed Message:\n");
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const msg = new Buffer(message);
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const prefixedMsg = ethWeb3.sha3(
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Buffer.concat([prefix, new Buffer(String(msg.length)), msg]).toString('utf8')
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);
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var strPrefixedMsg=prefixedMsg;
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var finalAddress=sigContractInstance.verify.call(strPrefixedMsg, res.v, res.r, '0x'+ res.s);
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return finalAddress;
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}
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function splitSig(sig) {
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return {
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v: ethWeb3.toDecimal('0x' + sig.slice(130, 132)),
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r: sig.slice(0, 66),
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s: sig.slice(66, 130)
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}
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}
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function sign(){
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var message = document.getElementById('txtMessage').value;
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var signMsg = signMessage(message);
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document.getElementById('dvSig').innerText = signMsg;
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}
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function verify(){
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var message = document.getElementById('txtMessage').value;
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var actAddr = verifySignedByAc(message, document.getElementById('dvSig').innerText);
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document.getElementById('dvSignedBy').innerText = actAddr;
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}
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function execute(){
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console.log("\n\n**********************************************************************");
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console.log("Steps to Run");
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console.log("**********************************************************************");
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console.log("1. Deploy the following conract in your ethereum environment");
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console.log(signatureContractCodeReadable);
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console.log("2. Set the following parameters (i.e. at the end of the code)");
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console.log("\ta. Ethereum URL");
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console.log("\tb. Ethereum Account Address");
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console.log("\tc. Ethereum Account Passphrase");
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console.log("\td. Signature Contract Address");
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console.log("\te. Message for signing");
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console.log("**********************************************************************");
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if(ethURL==''){
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console.log("Error: Ethereum URL is not specified");
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return;
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}
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if(defaultAc==''){
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console.log("Error: Account Address is not specified");
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return;
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}
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if(defaultAcPWD==''){
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console.log("Error: Account password is not specified");
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return;
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}
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if(sigContractAddress==''){
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console.log("Error: Signature Contract Address is not specified");
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return;
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}
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if(signMessage==''){
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console.log("Error: Message for signing is not specified");
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return;
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}
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console.log("Following parameters applied");
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console.log("\ta. Ethereum URL :",ethURL);
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console.log("\tb. Ethereum Account Address :",defaultAc);
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console.log("\tc. Ethereum Account Passphrase :",defaultAcPWD);
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console.log("\td. Signature Contract Address :",sigContractAddress);
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console.log("\te. Message for signing :",signMessage);
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console.log("**********************************************************************");
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console.log("Result");
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console.log("**********************************************************************");
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var sig=signMessage(signMessage);
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console.log("Signature");
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console.log(sig);
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var addr=verifySignedByAc(signMessage, sig);
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console.log("Signed By");
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console.log(addr);
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console.log("**********************************************************************");
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console.log("Exit");
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console.log("**********************************************************************");
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}
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// Please uncomment the below listed three lines of code and provide the required values
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// Value 1- Please provide the ethereum account address which you want to use to perform the operation
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//setAccount('<Provide the account address>');
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// Value 2- Please provide the password of the accound to be used
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//setPassword('<Provide teh password>');
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// Value 3- Please update the address of the contract after deployment
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// The contract code is made available at the top under signatureContractCodeReadable variable
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// Please deploy teh contract and update the contract address here
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//setContractAddress('<Provide the deployed contract address>');
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// Value 4- If required please update with a different message
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setEthereumURL('http://localhost:8545');
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// Value 5- If required please update with a Ethereum URL
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setMessage('This the test sign message');
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execute();
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