Add more checks for privateKeyModInverse

Author: kripod

lib/elliptic/index.js

@@ -79,6 +79,8 @@ exports.privateKeyNegate = function (privateKey) {
 
 exports.privateKeyModInverse = function (privateKey) {
   var bn = new BN(privateKey)
+  if (bn.cmp(ecparams.n) >= 0 || bn.isZero()) throw new Error(messages.EC_PRIVATE_KEY_RANGE_INVALID)
+
   return bn.invm(ecparams.n).toArrayLike(Buffer, 'be', 32)
 }
 

lib/js/index.js

@@ -24,7 +24,10 @@ exports.privateKeyNegate = function (privateKey) {
 }
 
 exports.privateKeyModInverse = function (privateKey) {
-  return BN.fromBuffer(privateKey).uinvm().toBuffer()
+  var bn = BN.fromBuffer(privateKey)
+  if (bn.isOverflow() || bn.isZero()) throw new Error(messages.EC_PRIVATE_KEY_RANGE_INVALID)
+
+  return bn.uinvm().toBuffer()
 }
 
 exports.privateKeyTweakAdd = function (privateKey, tweak) {

lib/messages.json

@@ -2,6 +2,7 @@
   "COMPRESSED_TYPE_INVALID": "compressed should be a boolean",
   "EC_PRIVATE_KEY_TYPE_INVALID": "private key should be a Buffer",
   "EC_PRIVATE_KEY_LENGTH_INVALID": "private key length is invalid",
+  "EC_PRIVATE_KEY_RANGE_INVALID": "private key range is invalid",
   "EC_PRIVATE_KEY_TWEAK_ADD_FAIL": "tweak out of range or resulting private key is invalid",
   "EC_PRIVATE_KEY_TWEAK_MUL_FAIL": "tweak out of range",
   "EC_PRIVATE_KEY_EXPORT_DER_FAIL": "couldn't export to DER format",

test/privatekey.js

@@ -158,6 +158,22 @@ module.exports = function (t, secp256k1) {
       t.end()
     })
 
+    t.test('private key is 0', function (t) {
+      t.throws(function () {
+        var privateKey = util.BN_ZERO.toArrayLike(Buffer, 'be', 32)
+        secp256k1.privateKeyModInverse(privateKey)
+      }, new RegExp('^Error: ' + messages.EC_PRIVATE_KEY_RANGE_INVALID + '$'))
+      t.end()
+    })
+
+    t.test('private key equal to N', function (t) {
+      t.throws(function () {
+        var privateKey = util.ec.curve.n.toArrayLike(Buffer, 'be', 32)
+        secp256k1.privateKeyModInverse(privateKey)
+      }, new RegExp('^Error: ' + messages.EC_PRIVATE_KEY_RANGE_INVALID + '$'))
+      t.end()
+    })
+
     util.repeat(t, 'random tests', util.env.repeat, function (t) {
       var privateKey = util.getPrivateKey()