📋Automating the end user address validation

Users paying in crypto will have to verify their sending address, which is a regulatory requirement on us.

If you have the relevant access, you can automate that step by pre-filling the address and automatically doing the signature in the background for the user.

All parameters must be URL encoded. Example:

/37KcpG6mEp+1oAan8/HLEvcfZFXUi6kTOxTHNjD3ZloxS8DL70v7lCmXiEyDOATm4hvewMzBO2d1n25QdJ8WBw=

must be passed as:

%2F37KcpG6mEp%2B1oAan8%2FHLEvcfZFXUi6kTOxTHNjD3ZloxS8DL70v7lCmXiEyDOATm4hvewMzBO2d1n25QdJ8WBw%3D

Parameter	Value	Description
addr	public address	Allows you to automatically provide the user's receiving or sending public address (the address has to be unique for each user, common addresses are not permitted and will be rejected)
code	4-digits code	Random 4 digits code between 1000 and 9999 that you need to generate for each address supplied with the addr parameter (don't use the same code for all addresses or the validation will be rejected)
hash	#	base64 encoded signature of the following message: MtPelerin-<code>. The private key used to sign the message has to be the one matching the public address given in addr. To test it, see Test vector below.
chain	arbitrum_mainnet avalanche_mainnet base_mainnet bsc_mainnet celo_mainnet mainnet matic_mainnet optimism_mainnet rsk_mainnet sonic_mainnet xdai_mainnet zksync_mainnet	Optional, only required to validate the address of a smart contract wallet (EIP1271)

Test vector

You can verify that your signature for the 'hash' parameter is correct by testing it with the following info:

• private key: 4142e80a872531fd1055f52ccab713d4c7f1eee28c33415558e74faeb516de2b

• address: 0x270402aeB8f4dAc8203915fC26F0768feA61b532

• code: 1234

• hash: /37KcpG6mEp+1oAan8/HLEvcfZFXUi6kTOxTHNjD3ZloxS8DL70v7lCmXiEyDOATm4hvewMzBO2d1n25QdJ8WBw=

or with the following info:

• seed: bamboo feed assist glove soda merry medal vanish almost solid bean loop

• derivation path: m/44'/60'/0'/0/0

• private key: 78ba65f1cc9427fab632340ae4d705b1485fba9f73ab5a24816907d36d5729e9

• address: 0xEa22e16EA50A43092853329F3cEEa0825Cb9B03e

• code: 1234

• hash: yrXNJSmMc4wvVyKEzN4cEmLTvEaridjqTULZAfMwYAMM5PgBz4fCoIWNLr5NwKhxOYiPpI2vhMlKCihWadUw5xs=

Vanilla JS code with Metamask as signer

const toBase64 = (u8) =>
    btoa(String.fromCharCode.apply(null, u8));

const fromBase64 = (str) =>
    atob(str).split('').map(function (c) { return c.charCodeAt(0); });

const fromHexString = (hexString) =>
  Uint8Array.from(hexString.match(/.{1,2}/g).map((byte) => parseInt(byte, 16)));

const toHexString = (bytes) =>
  bytes.reduce((str, byte) => str + byte.toString(16).padStart(2, '0'), '');

/* Example for private key 78ba65f1cc9427fab632340ae4d705b1485fba9f73ab5a24816907d36d5729e9 */
const code = '1234';
const message = 'MtPelerin-' + code;
const address = '0xEa22e16EA50A43092853329F3cEEa0825Cb9B03e'; // ethereum address

window.ethereum.request({
  method: 'personal_sign',
  params: [message, address],
}).then((hash) => {
    // hash should be 0xcab5cd25298c738c2f572284ccde1c1262d3bc46ab89d8ea4d42d901f33060030ce4f801cf87c2a0858d2ebe4dc0a87139888fa48daf84c94a0a285669d530e71b
    const base64Hash = toBase64(fromHexString(hash.replace('0x', '')));
    // base64Hash should be yrXNJSmMc4wvVyKEzN4cEmLTvEaridjqTULZAfMwYAMM5PgBz4fCoIWNLr5NwKhxOYiPpI2vhMlKCihWadUw5xs=
    return base64Hash;
}).catch(console.log);

NodeJS code with ethers.Wallet as signer

const ethers = require('ethers');

/* Example for private key 78ba65f1cc9427fab632340ae4d705b1485fba9f73ab5a24816907d36d5729e9 */
const code = '1234';
const message = 'MtPelerin-' + code;
const address = '0xEa22e16EA50A43092853329F3cEEa0825Cb9B03e'; // ethereum address

const wallet = new ethers.Wallet('0x78ba65f1cc9427fab632340ae4d705b1485fba9f73ab5a24816907d36d5729e9');

wallet.signMessage(message).then((hash) => { 
    // hash should be 0xcab5cd25298c738c2f572284ccde1c1262d3bc46ab89d8ea4d42d901f33060030ce4f801cf87c2a0858d2ebe4dc0a87139888fa48daf84c94a0a285669d530e71b
    const base64Hash = Buffer.from(hash.replace('0x', ''), 'hex').toString('base64');
    // base64Hash should be yrXNJSmMc4wvVyKEzN4cEmLTvEaridjqTULZAfMwYAMM5PgBz4fCoIWNLr5NwKhxOYiPpI2vhMlKCihWadUw5xs=
    return base64Hash;
}).catch(console.log);