From e8ad38993e29747098f7fd1594dde4ce893ba802 Mon Sep 17 00:00:00 2001
From: Filip Skokan <panva.ip@gmail.com>
Date: Wed, 1 Jul 2020 13:13:34 +0200
Subject: [PATCH] fix: handle private EC keys without public component (#86)

Only possible to handle when KeyObject API is available in the runtime.

closes #85
---
 lib/help/key_utils.js   | 18 +++++++++++++++---
 test/jwk/import.test.js | 27 ++++++++++++++++++++++++++-
 2 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/lib/help/key_utils.js b/lib/help/key_utils.js
index 887855ea00..efd7f90bec 100644
--- a/lib/help/key_utils.js
+++ b/lib/help/key_utils.js
@@ -4,6 +4,7 @@ const { EOL } = require('os')
 
 const errors = require('../errors')
 
+const { keyObjectSupported } = require('./runtime_support')
 const { createPublicKey } = require('./key_object')
 const base64url = require('./base64url')
 const asn1 = require('./asn1')
@@ -89,10 +90,21 @@ const keyObjectToJWK = {
       const ECPrivateKey = asn1.get('ECPrivateKey')
 
       const { privateKey, algorithm: { parameters: { value: crv } } } = PrivateKeyInfo.decode(der)
-      const { privateKey: d, publicKey: { data: publicKey } } = ECPrivateKey.decode(privateKey)
+      const { privateKey: d, publicKey } = ECPrivateKey.decode(privateKey)
+
+      if (typeof publicKey === 'undefined') {
+        if (keyObjectSupported) {
+          return {
+            ...keyObjectToJWK.ec.public(createPublicKey(keyObject)),
+            d: base64url.encodeBuffer(d)
+          }
+        }
 
-      const x = publicKey.slice(1, ((publicKey.length - 1) / 2) + 1)
-      const y = publicKey.slice(((publicKey.length - 1) / 2) + 1)
+        throw new errors.JOSENotSupported('Private EC keys without the public key embedded are not supported in your Node.js runtime version')
+      }
+
+      const x = publicKey.data.slice(1, ((publicKey.data.length - 1) / 2) + 1)
+      const y = publicKey.data.slice(((publicKey.data.length - 1) / 2) + 1)
 
       return {
         kty: 'EC',
diff --git a/test/jwk/import.test.js b/test/jwk/import.test.js
index a9aed164a4..dc21e1b731 100644
--- a/test/jwk/import.test.js
+++ b/test/jwk/import.test.js
@@ -3,7 +3,7 @@ const test = require('ava')
 const { JWS, JWE, JWK: { asKey, importKey, generate }, errors } = require('../..')
 
 const { edDSASupported, keyObjectSupported } = require('../../lib/help/runtime_support')
-const { createSecretKey } = require('../../lib/help/key_object')
+const { createSecretKey, createPrivateKey } = require('../../lib/help/key_object')
 const { generateKeyPairSync } = require('../macros/generate')
 const fixtures = require('../fixtures')
 
@@ -177,3 +177,28 @@ if (keyObjectSupported) {
     }, { instanceOf: errors.JOSENotSupported, code: 'ERR_JOSE_NOT_SUPPORTED', message: 'X.509 certificates are not supported in your Node.js runtime version' })
   })
 }
+
+// https://github.com/panva/jose/issues/85
+{
+  const pem = `-----BEGIN PRIVATE KEY-----
+MEECAQAwEwYHKoZIzj0CAQYIKoZIzj0DAQcEJzAlAgEBBCCXpUVoM4DfOtMyRVtC
+eGSpVL+1tMBirnUGJHY6Y7mSHg==
+-----END PRIVATE KEY-----`
+
+  if (keyObjectSupported) {
+    test('EC private keys without public one', t => {
+      asKey(createPrivateKey(pem))
+      asKey(pem)
+      t.pass()
+    })
+  } else {
+    test('EC private keys without public one', t => {
+      t.throws(() => {
+        asKey(createPrivateKey(pem))
+      }, { instanceOf: errors.JOSENotSupported, code: 'ERR_JOSE_NOT_SUPPORTED', message: 'Private EC keys without the public key embedded are not supported in your Node.js runtime version' })
+      t.throws(() => {
+        asKey(pem)
+      }, { instanceOf: errors.JOSENotSupported, code: 'ERR_JOSE_NOT_SUPPORTED', message: 'Private EC keys without the public key embedded are not supported in your Node.js runtime version' })
+    })
+  }
+}