feat: crypto interface (#2)

* docs: initial crypto readme

* feat: add basic crypto interface test suite

* feat: add optional remotepeer for inbound

feat: add errors export

* docs(fix): update src/crypto/README.md

Co-Authored-By: Vasco Santos <vasco.santos@moxy.studio>

test/crypto/compliance.spec.js

@@ -0,0 +1,13 @@
+/* eslint-env mocha */
+'use strict'
+
+const tests = require('../../src/crypto/tests')
+const mockCrypto = require('./mock-crypto')
+
+describe('compliance tests', () => {
+  tests({
+    setup () {
+      return mockCrypto
+    }
+  })
+})

test/crypto/mock-crypto.js

@@ -0,0 +1,75 @@
+'use strict'
+
+const PeerId = require('peer-id')
+const handshake = require('it-handshake')
+const duplexPair = require('it-pair/duplex')
+const pipe = require('it-pipe')
+const { UnexpectedPeerError } = require('../../src/crypto/errors')
+
+// A basic transform that does nothing to the data
+const transform = () => {
+  return (source) => (async function * () {
+    for await (const chunk of source) {
+      yield chunk
+    }
+  })()
+}
+
+module.exports = {
+  protocol: 'insecure',
+  secureInbound: async (localPeer, duplex, expectedPeer) => {
+    // 1. Perform a basic handshake.
+    const shake = handshake(duplex)
+    shake.write(localPeer.id)
+    const remoteId = await shake.read()
+    const remotePeer = new PeerId(remoteId.slice())
+    shake.rest()
+
+    if (expectedPeer && expectedPeer.id !== remotePeer.id) {
+      throw new UnexpectedPeerError()
+    }
+
+    // 2. Create your encryption box/unbox wrapper
+    const wrapper = duplexPair()
+    const encrypt = transform() // Use transform iterables to modify data
+    const decrypt = transform()
+
+    pipe(
+      wrapper[0], // We write to wrapper
+      encrypt, // The data is encrypted
+      shake.stream, // It goes to the remote peer
+      decrypt, // Decrypt the incoming data
+      wrapper[0] // Pipe to the wrapper
+    )
+
+    return {
+      conn: wrapper[1],
+      remotePeer
+    }
+  },
+  secureOutbound: async (localPeer, duplex, remotePeer) => {
+    // 1. Perform a basic handshake.
+    const shake = handshake(duplex)
+    shake.write(localPeer.id)
+    const remoteId = await shake.read()
+    shake.rest()
+
+    // 2. Create your encryption box/unbox wrapper
+    const wrapper = duplexPair()
+    const encrypt = transform()
+    const decrypt = transform()
+
+    pipe(
+      wrapper[0], // We write to wrapper
+      encrypt, // The data is encrypted
+      shake.stream, // It goes to the remote peer
+      decrypt, // Decrypt the incoming data
+      wrapper[0] // Pipe to the wrapper
+    )
+
+    return {
+      conn: wrapper[1],
+      remotePeer: new PeerId(remoteId.slice())
+    }
+  }
+}