use Buffer.alloc instead of copy

Author: Daniel Cousens

lib/der.js

@@ -50,11 +50,6 @@ var EC_PRIVKEY_EXPORT_DER_UNCOMPRESSED = Buffer.from([
   0x00
 ])
 
-var ZERO_BUFFER_32 = Buffer.from([
-  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
-])
-
 exports.privateKeyExport = function (privateKey, publicKey, compressed) {
   var result = Buffer.from(compressed ? EC_PRIVKEY_EXPORT_DER_COMPRESSED : EC_PRIVKEY_EXPORT_DER_UNCOMPRESSED)
   privateKey.copy(result, compressed ? 8 : 9)
@@ -114,8 +109,8 @@ exports.signatureExport = function (sigObj) {
 }
 
 exports.signatureImport = function (sig) {
-  var r = Buffer.from(ZERO_BUFFER_32)
-  var s = Buffer.from(ZERO_BUFFER_32)
+  var r = Buffer.alloc(32)
+  var s = Buffer.alloc(32)
 
   try {
     var sigObj = bip66.decode(sig)
@@ -134,8 +129,8 @@ exports.signatureImport = function (sig) {
 }
 
 exports.signatureImportLax = function (sig) {
-  var r = Buffer.from(ZERO_BUFFER_32)
-  var s = Buffer.from(ZERO_BUFFER_32)
+  var r = Buffer.alloc(32)
+  var s = Buffer.alloc(32)
 
   var length = sig.length
   var index = 0