feat: implement generateEphemeralKeyPair

src/ephemeral-keys.js

@@ -0,0 +1,30 @@
+'use strict'
+
+const EC = require('elliptic').ec
+
+const curveMap = {
+  'P-256': 'p256',
+  'P-384': 'p384',
+  'P-521': 'p521'
+}
+
+// Generates an ephemeral public key and returns a function that will compute
+// the shared secret key.
+//
+// Focuses only on ECDH now, but can be made more general in the future.
+module.exports = (curveName) => {
+  const curve = curveMap[curveName]
+  if (!curve) {
+    throw new Error('unsupported curve passed')
+  }
+
+  const ec = new EC(curve)
+
+  const priv = ec.genKeyPair()
+
+  return (theirPub) => {
+    const pub = ec.keyFromPublic(theirPub, 'hex')
+
+    return priv.derive(pub.getPublic()).toBuffer('le')
+  }
+}

src/index.js

@@ -8,6 +8,9 @@ const pbm = protobuf(fs.readFileSync(path.join(__dirname, './crypto.proto')))
 exports.utils = require('./utils')
 const keys = exports.keys = require('./keys')
 
+exports.keyStretcher = require('./key-stretcher')
+exports.generateEphemeralKeyPair = require('./ephemeral-keys')
+
 // Generates a keypair of the given type and bitsize
 exports.generateKeyPair = (type, bits, cb) => {
   let key = keys[type.toLowerCase()]
@@ -18,20 +21,6 @@ exports.generateKeyPair = (type, bits, cb) => {
   key.generateKeyPair(bits, cb)
 }
 
-// Generates an ephemeral public key and returns a function that will compute
-// the shared secret key.
-//
-// Focuses only on ECDH now, but can be made more general in the future.
-exports.generateEphemeralKeyPair = (curveName, cb) => {
-  throw new Error('Not implemented')
-}
-
-// Generates a set of keys for each party by stretching the shared key.
-// (myIV, theirIV, myCipherKey, theirCipherKey, myMACKey, theirMACKey)
-exports.keyStretcher = (cipherType, hashType, secret) => {
-  throw new Error('Not implemented')
-}
-
 // Converts a protobuf serialized public key into its
 // representative object
 exports.unmarshalPublicKey = (buf) => {

src/key-stretcher.js

@@ -0,0 +1,7 @@
+'use strict'
+
+// Generates a set of keys for each party by stretching the shared key.
+// (myIV, theirIV, myCipherKey, theirCipherKey, myMACKey, theirMACKey)
+module.exports = (cipherType, hashType, secret) => {
+  throw new Error('Not implemented')
+}