diff --git a/README.md b/README.md
index 91a1c40..2c237ae 100644
--- a/README.md
+++ b/README.md
@@ -4,9 +4,9 @@ A simple alipay ruby gem, without unnecessary magic or wraper, it's directly fac
 
 It contain this API:
 
-* Generate payment url
+* Generate payment url (web, wap)
 * Send goods
-* Verify notify
+* Verify notify (web, wap, app)
 
 Please read alipay official document first: https://b.alipay.com/order/techService.htm .
 
@@ -40,7 +40,7 @@ Alipay.key = 'YOUR_KEY'
 Alipay.seller_email = 'YOUR_SELLER_EMAIL'
 ```
 
-### Generate payment url
+### Generate payment url for web
 
 ```ruby
 options = {
@@ -125,7 +125,7 @@ Notify Url Demo: http://git.io/pst4Tw
 
 ```ruby
 # Example in rails,
-# both notify url MUST be set when generate payment url
+# notify url MUST be set when generate payment url
 
 def alipay_web_notify
   # except :controller_name, :action_name, :host, etc.
@@ -152,6 +152,18 @@ def alipay_wap_notify
     render :text => 'error'
   end
 end
+
+def alipay_app_notify
+  # except :controller_name, :action_name, :host, etc.
+  notify_params = params.except(*request.path_parameters.keys)
+
+  if Alipay::Notify::App.verify?(notify_params)
+    # valid notify, code your business logic.
+    render :text => 'success'
+  else
+    render :text => 'error'
+  end
+end
 ```
 
 ## Contributing
diff --git a/lib/alipay/notify.rb b/lib/alipay/notify.rb
index 6dcf230..f87d9b2 100644
--- a/lib/alipay/notify.rb
+++ b/lib/alipay/notify.rb
@@ -9,6 +9,13 @@ def self.verify?(params)
       end
     end
 
+    module App
+      def self.verify?(params)
+        params = Utils.stringify_keys(params)
+        Sign::App.verify?(params) && Notify.verify_notify_id?(params['notify_id'])
+      end
+    end
+
     def self.verify?(params)
       params = Utils.stringify_keys(params)
       Sign.verify?(params) && verify_notify_id?(params['notify_id'])
diff --git a/lib/alipay/sign.rb b/lib/alipay/sign.rb
index e669298..f489eab 100644
--- a/lib/alipay/sign.rb
+++ b/lib/alipay/sign.rb
@@ -1,4 +1,6 @@
 require 'digest/md5'
+require 'openssl'
+require 'base64'
 
 module Alipay
   module Sign
@@ -31,5 +33,28 @@ def self.verify?(params)
         params['sign'] == Digest::MD5.hexdigest("#{query}#{Alipay.key}")
       end
     end
+
+    module App
+      # Alipay public key
+      PEM = "-----BEGIN PUBLIC KEY-----\n" \
+            "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCnxj/9qwVfgoUh/y2W89L6BkRA\n" \
+            "FljhNhgPdyPuBV64bfQNN1PjbCzkIM6qRdKBoLPXmKKMiFYnkd6rAoprih3/PrQE\n" \
+            "B/VsW8OoM8fxn67UDYuyBTqA23MML9q1+ilIZwBC2AQ2UBVOrFXfFl75p6/B5Ksi\n" \
+            "NG9zpgmLCUYuLkxpLQIDAQAB\n" \
+            "-----END PUBLIC KEY-----"
+
+      def self.verify?(params)
+        params = Utils.stringify_keys(params)
+
+        pkey = OpenSSL::PKey::RSA.new(PEM)
+        digest = OpenSSL::Digest::SHA1.new
+
+        params.delete('sign_type')
+        sign = params.delete('sign')
+        to_sign = params.sort.map { |item| item.join('=') }.join('&')
+
+        pkey.verify(digest, Base64.decode64(sign), to_sign)
+      end
+    end
   end
 end
diff --git a/lib/alipay/utils.rb b/lib/alipay/utils.rb
index 7220ceb..0c86e58 100644
--- a/lib/alipay/utils.rb
+++ b/lib/alipay/utils.rb
@@ -11,8 +11,9 @@ def self.stringify_keys(hash)
     # 退款批次号，支付宝通过此批次号来防止重复退款操作，所以此号生成后最好直接保存至数据库，不要在显示页面的时候生成
     # 共 24 位(8 位当前日期 + 9 位纳秒 + 1 位随机数)
     def self.generate_batch_no
-      time = Time.now
-      time.strftime('%Y%m%d%H%M%S') + time.nsec.to_s + Random.new.rand(1..9).to_s
+      t = Time.now
+      batch_no = t.strftime('%Y%m%d%H%M%S') + t.nsec.to_s
+      batch_no.ljust(24, Random.new.rand(1..9).to_s)
     end
   end
 end