diff --git a/src/packet/sym_encrypted_integrity_protected.js b/src/packet/sym_encrypted_integrity_protected.js
index 0ffc8efc..db803423 100644
--- a/src/packet/sym_encrypted_integrity_protected.js
+++ b/src/packet/sym_encrypted_integrity_protected.js
@@ -38,8 +38,9 @@ module.exports = SymEncryptedIntegrityProtected;
 
 var util = require('../util.js'),
   crypto = require('../crypto'),
-  config = require('../config'),
-  enums = require('../enums.js');
+  enums = require('../enums.js'),
+  nodeCrypto = util.getNodeCrypto(),
+  Buffer = util.getNodeBuffer();
 
 /**
  * @constructor
@@ -98,15 +99,10 @@ SymEncryptedIntegrityProtected.prototype.encrypt = function (sessionKeyAlgorithm
   if(sessionKeyAlgorithm.substr(0,3) === 'aes') {
     var blockSize = crypto.cipher[sessionKeyAlgorithm].blockSize;
     // Node crypto library. Not clear that it is faster than asmCrypto
-    if(util.detectNode() && config.useNative) {
-      var nodeCrypto = require('crypto');
-      var Buffer = require('buffer').Buffer;
+    if(nodeCrypto) {
       var cipherObj = new nodeCrypto.createCipheriv('aes-' + sessionKeyAlgorithm.substr(3,3) + '-cfb',
         new Buffer(key), new Buffer(new Uint8Array(blockSize)));
       this.encrypted = new Uint8Array(cipherObj.update(new Buffer(util.concatUint8Array([prefix, tohash]))));
-      //var cipherObj = new nodeCrypto.createCipheriv('aes-' + sessionKeyAlgorithm.substr(3,3) + '-cfb',
-      //  util.Uint8Array2str(key), util.Uint8Array2str(new Uint8Array(blockSize)));
-      //this.encrypted = new Uint8Array(cipherObj.update(util.Uint8Array2str(util.concatUint8Array([prefix, tohash]))));
     }
     else {
       this.encrypted = asmCrypto.AES_CFB.encrypt(util.concatUint8Array([prefix, tohash]), key);
@@ -134,9 +130,7 @@ SymEncryptedIntegrityProtected.prototype.decrypt = function (sessionKeyAlgorithm
   if(sessionKeyAlgorithm.substr(0,3) === 'aes') {
     var blockSize = crypto.cipher[sessionKeyAlgorithm].blockSize;
     // Node crypto library. Not clear that it is faster than asmCrypto
-    if(util.detectNode() && config.useNative) {
-      var nodeCrypto = require('crypto');
-      var Buffer = require('buffer').Buffer;
+    if(nodeCrypto) {
       var decipherObj = new nodeCrypto.createDecipheriv('aes-' + sessionKeyAlgorithm.substr(3,3) + '-cfb',
         new Buffer(key), new Buffer(new Uint8Array(blockSize)));
       decrypted = new Uint8Array(decipherObj.update(new Buffer(this.encrypted)));
diff --git a/src/util.js b/src/util.js
index 64b0f0f1..2d889a6b 100644
--- a/src/util.js
+++ b/src/util.js
@@ -408,11 +408,10 @@ module.exports = {
   /**
    * Get native Web Cryptography api. The default configuration is to use
    * the api when available. But it can also be deactivated with config.useNative
-   * @return {Object} The SubtleCrypto api or 'undefined'
+   * @return {Object}   The SubtleCrypto api or 'undefined'
    */
   getWebCrypto: function() {
     if (!config.useNative) {
-      // make web crypto optional
       return;
     }
 
@@ -465,6 +464,32 @@ module.exports = {
    */
   detectNode: function() {
     return typeof window === 'undefined';
+  },
+
+  /**
+   * Get native Node.js crypto api. The default configuration is to use
+   * the api when available. But it can also be deactivated with config.useNative
+   * @return {Object}   The crypto module or 'undefined'
+   */
+  getNodeCrypto: function() {
+    if (!this.detectNode() || !config.useNative) {
+      return;
+    }
+
+    return require('crypto');
+  },
+
+  /**
+   * Get native Node.js Buffer constructor. This should be used since
+   * Buffer is not available under browserify.
+   * @return {Function}   The Buffer constructor or 'undefined'
+   */
+  getNodeBuffer: function() {
+    if (!this.detectNode()) {
+      return;
+    }
+
+    return require('buffer').Buffer;
   }
 
 };