chore: connection encryption example test (#843)

examples/connection-encryption/1.js

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+'use strict'
+
+const Libp2p = require('../..')
+const TCP = require('libp2p-tcp')
+const Mplex = require('libp2p-mplex')
+const { NOISE } = require('libp2p-noise')
+
+const pipe = require('it-pipe')
+
+const createNode = async () => {
+  const node = await Libp2p.create({
+    addresses: {
+      listen: ['/ip4/0.0.0.0/tcp/0']
+    },
+    modules: {
+      transport: [TCP],
+      streamMuxer: [Mplex],
+      connEncryption: [NOISE]
+    }
+  })
+
+  await node.start()
+
+  return node
+}
+
+;(async () => {
+  const [node1, node2] = await Promise.all([
+    createNode(),
+    createNode()
+  ])
+
+  node1.peerStore.addressBook.set(node2.peerId, node2.multiaddrs)
+
+  node2.handle('/a-protocol', ({ stream }) => {
+    pipe(
+      stream,
+      async function (source) {
+        for await (const msg of source) {
+          console.log(msg.toString())
+        }
+      }
+    )
+  })
+
+  const { stream } = await node1.dialProtocol(node2.peerId, '/a-protocol')
+
+  await pipe(
+    ['This information is sent out encrypted to the other peer'],
+    stream
+  )
+})();

examples/connection-encryption/README.md

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+# Connection Encryption
+
+libp2p can leverage the encrypted communications from the transports it uses (i.e WebRTC). To ensure that every connection is encrypted, independently of how it was set up, libp2p also supports a set of modules that encrypt every communication established.
+
+We call this usage a _connection upgrade_ where given a connection between peer A to peer B, a protocol handshake can be performed that gives that connection new properties.
+
+A byproduct of having these encrypted communications modules is that we can authenticate the peers we are dialing to. You might have noticed that every time we dial to a peer in libp2p space, we always use its PeerId at the end (e.g /ip4/127.0.0.1/tcp/89765/p2p/QmWCbVw1XZ8hiYBwwshPce2yaTDYTqTaP7GCHGpry3ykWb), this PeerId is generated by hashing the Public Key of the peer. With this, we can create a crypto challenge when dialing to another peer and prove that peer is the owner of a PrivateKey that matches the Public Key we know.
+
+# 1. Set up encrypted communications
+
+We will build this example on top of example for [Protocol and Stream Multiplexing](../protocol-and-stream-multiplexing). You will need the `libp2p-noise` module to complete it, go ahead and `npm install libp2p-noise`.
+
+To add them to your libp2p configuration, all you have to do is:
+
+```JavaScript
+const Libp2p = require('libp2p')
+const { NOISE } = require('libp2p-noise')
+
+const createNode = () => {
+  return Libp2p.create({
+    modules: {
+      transport: [ TCP ],
+      streamMuxer: [ Mplex ],
+      // Attach noise as the crypto channel to use
+      connEncryption: [ NOISE ]
+    }
+  })
+}
+```
+
+And that's it, from now on, all your libp2p communications are encrypted. Try running the example [1.js](./1.js) to see it working.

examples/connection-encryption/test.js

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+'use strict'
+
+const path = require('path')
+const execa = require('execa')
+const pDefer = require('p-defer')
+const uint8ArrayToString = require('uint8arrays/to-string')
+
+async function test () {
+  const messageReceived = pDefer()
+  process.stdout.write('1.js\n')
+
+  const proc = execa('node', [path.join(__dirname, '1.js')], {
+    cwd: path.resolve(__dirname),
+    all: true
+  })
+
+  proc.all.on('data', async (data) => {
+    process.stdout.write(data)
+
+    const s = uint8ArrayToString(data)
+    if (s.includes('This information is sent out encrypted to the other peer')) {
+      messageReceived.resolve()
+    }
+  })
+
+  await messageReceived.promise
+  proc.kill()
+}
+
+module.exports = test