diff --git a/lib/we_whisper/cipher.rb b/lib/we_whisper/cipher.rb
index 3bc1605..b5fdd45 100644
--- a/lib/we_whisper/cipher.rb
+++ b/lib/we_whisper/cipher.rb
@@ -35,7 +35,6 @@ module WeWhisper
       decode_padding(plain)
     end
 
-    # app_id or corp_id
     def pack(content, app_id)
       random = SecureRandom.hex(8)
       text = content.force_encoding('ASCII-8BIT')
@@ -65,7 +64,7 @@ module WeWhisper
 
     def decode_padding(plain)
       pad = plain.bytes[-1]
-      # no padding
+      # if padding is less than 1 or larger than block size, then set to 0
       pad = 0 if pad < 1 || pad > BLOCK_SIZE
       plain[0...(plain.length - pad)]
     end
diff --git a/lib/we_whisper/signature.rb b/lib/we_whisper/signature.rb
index a84d0dd..a065c80 100644
--- a/lib/we_whisper/signature.rb
+++ b/lib/we_whisper/signature.rb
@@ -2,9 +2,9 @@ require 'digest/sha2'
 
 module WeWhisper
   module Signature
-    def self.hexdigest(token, timestamp, nonce, msg_encrypt)
+    def self.sign(token, timestamp, nonce, encrypted)
       array = [token, timestamp, nonce]
-      array << msg_encrypt unless msg_encrypt.nil?
+      array << encrypted unless encrypted.nil?
       Digest::SHA1.hexdigest array.compact.collect(&:to_s).sort.join
     end
   end
diff --git a/lib/we_whisper/whisper.rb b/lib/we_whisper/whisper.rb
index b5212b9..71773e7 100644
--- a/lib/we_whisper/whisper.rb
+++ b/lib/we_whisper/whisper.rb
@@ -35,7 +35,7 @@ module WeWhisper
       # 2. If we need to validate signature, generate one from the encrypted text
       #    and check with the Signature in message
       if options[:assert_signature] && signature = Message.get_signature_from_messge(message)
-        sign = Signature.hexdigest(token, timestamp, nonce, encrypted_text)
+        sign = Signature.sign(token, timestamp, nonce, encrypted_text)
         raise InvalidSignature if sign != signature
       end
 
@@ -55,7 +55,7 @@ module WeWhisper
       encrypt = Base64.strict_encode64(encrypt(pack(message, appid), encoding_aes_key))
 
       # 2. Create signature
-      sign = Signature.hexdigest(token, timestamp, nonce, encrypt)
+      sign = Signature.sign(token, timestamp, nonce, encrypt)
 
       # 3. Construct xml
       Message.to_xml(encrypt, sign, timestamp, nonce)
diff --git a/spec/we_whisper/signature_spec.rb b/spec/we_whisper/signature_spec.rb
new file mode 100644
index 0000000..5e471fd
--- /dev/null
+++ b/spec/we_whisper/signature_spec.rb
@@ -0,0 +1,15 @@
+require 'spec_helper'
+
+describe WeWhisper::Signature do
+
+  let(:timestamp) { "1415979516" }
+  let(:nonce)     { "1320562132" }
+  let(:signature) { "096d8cda45e4678ca23460f6b8cd281b3faf1fc3" }
+  let(:token)     { "spamtest" }
+  let(:encrypted) { "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" }
+
+  it "signs message" do
+    expect(subject.sign(token, timestamp, nonce, encrypted)).to eq signature
+  end
+
+end
--
libgit2 0.21.0