fix browser version; readme update

downloadKeys.js

@@ -0,0 +1,43 @@
+const axios = require('axios')
+const path = require('path')
+const fs = require('fs')
+const files = ['withdraw.json', 'withdraw_proving_key.bin', 'Verifier.sol', 'withdraw_verification_key.json']
+const circuitsPath = 'build/circuits'
+const contractsPath = 'build/contracts'
+
+async function downloadFile({ url, path }) {
+  const writer = fs.createWriteStream(path)
+
+  const response = await axios({
+    url,
+    method: 'GET',
+    responseType: 'stream'
+  })
+
+  response.data.pipe(writer)
+
+  return new Promise((resolve, reject) => {
+    writer.on('finish', resolve)
+    writer.on('error', reject)
+  })
+}
+
+async function main() {
+  const release = await axios.get('https://api.github.com/repos/tornadocash/tornado-core/releases/latest')
+  const { assets } = release.data
+  if (!fs.existsSync(circuitsPath)){
+    fs.mkdirSync(circuitsPath, { recursive: true })
+    fs.mkdirSync(contractsPath, { recursive: true })
+  }
+  for(let asset of assets) {
+    if (files.includes(asset.name)) {
+      console.log(`Downloading ${asset.name} ...`)
+      await downloadFile({
+        url: asset.browser_download_url,
+        path: path.resolve(__dirname, circuitsPath, asset.name)
+      })
+    }
+  }
+}
+
+main()