go interop test for ephemeral keys

src/ephemeral-keys.js

@@ -22,10 +22,11 @@ module.exports = (curveName) => {
 
   const priv = ec.genKeyPair()
 
-  const genSharedKey = (theirPub) => {
+  // forcePrivate is used for testing only
+  const genSharedKey = (theirPub, forcePrivate) => {
     const pub = ec.keyFromPublic(theirPub, 'hex')
-
-    return priv.derive(pub.getPublic()).toBuffer('le')
+    const p = forcePrivate || priv
+    return p.derive(pub.getPublic()).toBuffer('le')
   }
 
   return {

test/ephemeral-keys.spec.js

@@ -2,8 +2,10 @@
 'use strict'
 
 const expect = require('chai').expect
+const EC = require('elliptic').ec
 
 const crypto = require('../src')
+const fixtures = require('./fixtures/go-elliptic-key')
 
 describe('generateEphemeralKeyPair', () => {
   it('returns a function that generates a shared secret', () => {
@@ -18,4 +20,25 @@ describe('generateEphemeralKeyPair', () => {
       res.key
     ).to.exist
   })
+
+  describe('go interop', () => {
+    it('generates a shared secret', () => {
+      const curve = fixtures.curve
+      const ec = new EC(fixtures.curveJs)
+      const bobPrivate = ec.keyFromPrivate(fixtures.bob.private, 'binary')
+
+      const alice = crypto.generateEphemeralKeyPair(curve)
+      const bob = {
+        key: fixtures.bob.public,
+        // this is using bobs private key from go ipfs
+        // instead of alices
+        genSharedKey: (key) => alice.genSharedKey(key, bobPrivate)
+      }
+
+      const s1 = alice.genSharedKey(bob.key)
+      const s2 = bob.genSharedKey(alice.key)
+
+      expect(s1.equals(s2)).to.be.eql(true)
+    })
+  })
 })

test/fixtures/go-elliptic-key.js

@@ -0,0 +1,14 @@
+'use strict'
+
+module.exports = {
+  curve: 'P-256',
+  curveJs: 'p256',
+  bob: {
+    private: [
+      231, 236, 69, 16, 13, 92, 76, 83, 75, 40, 32, 71, 235, 187, 29, 214, 98, 231, 42, 5, 80, 89, 58, 175, 8, 95, 86, 50, 44, 214, 4, 172
+    ],
+    public: new Buffer([
+      4, 160, 169, 215, 85, 152, 11, 209, 69, 105, 17, 51, 49, 83, 214, 171, 157, 73, 165, 85, 28, 196, 161, 234, 87, 149, 139, 76, 123, 37, 174, 194, 67, 167, 18, 34, 164, 35, 171, 164, 238, 141, 199, 206, 86, 130, 183, 88, 63, 121, 110, 150, 229, 10, 213, 176, 181, 1, 98, 20, 246, 85, 212, 200, 229
+    ])
+  }
+}