enable to specify message encoding

Author: mokemokechicken

README.md

@@ -28,7 +28,7 @@ validator.validate(message, function (err, message) {
         // Your message could not be validated.
         return;
     }
-   
+
     // message has been validated and its signature checked.
 });
 ```
@@ -79,7 +79,7 @@ validator.validate(message, function (err, message) {
         console.error(err);
         return;
     }
-   
+
     if (message['Type'] === 'SubscriptionConfirmation') {
         https.get(message['SubscribeURL'], function (res) {
           // You have confirmed your endpoint subscription
@@ -88,6 +88,15 @@ validator.validate(message, function (err, message) {
 });
 ```
 
+If an incoming message includes multibyte characters and its encoding is utf8,
+set the encoding to `validator`.
+
+```javascript
+var MessageValidator = require('sns-validator'),
+    validator = new MessageValidator();
+validator.encoding = 'utf8';
+```
+
 ### Receiving a Notification
 
 To receive a notification, use the same code as the preceding example, but

index.js

@@ -88,7 +88,7 @@ var getCertificate = function (certUrl, cb) {
     }).on('error', cb)
 };
 
-var validateSignature = function (message, cb) {
+var validateSignature = function (message, cb, encoding) {
     if (message['SignatureVersion'] !== '1') {
         cb(new Error('The signature version '
             + message['SignatureVersion'] + ' is not supported.'));
@@ -99,7 +99,7 @@ var validateSignature = function (message, cb) {
     for (var i = 0; i < signableKeys.length; i++) {
         if (signableKeys[i] in message) {
             verifier.update(signableKeys[i] + "\n"
-                + message[signableKeys[i]] + "\n");
+                + message[signableKeys[i]] + "\n", encoding);
         }
     }
 
@@ -123,8 +123,9 @@ var validateSignature = function (message, cb) {
  * @constructor
  * @param {RegExp} [hostPattern=/^sns\.[a-zA-Z0-9\-]{3,}\.amazonaws\.com(\.cn)?$/] - A pattern used to validate that a message's certificate originates from a trusted domain.
  */
-function MessageValidator(hostPattern) {
+function MessageValidator(hostPattern, encoding) {
     this.hostPattern = hostPattern || defaultHostPattern;
+    this.encoding = encoding;
 }
 
 /**
@@ -156,7 +157,7 @@ MessageValidator.prototype.validate = function (hash, cb) {
         return;
     }
 
-    validateSignature(hash, cb);
+    validateSignature(hash, cb, this.encoding);
 };
 
 module.exports = MessageValidator;

package.json

@@ -1,6 +1,6 @@
 {
   "name": "sns-validator",
-  "version": "0.1.0",
+  "version": "0.2.1",
   "description": "A standalone validator for inbound SNS HTTP messages. No dependency on the AWS SDK for JavaScript.",
   "repository": {
     "type": "git",