diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..0d20b64
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+*.pyc
diff --git a/AES_CMAC.pyc b/AES_CMAC.pyc
deleted file mode 100644
index 536f3f8..0000000
Binary files a/AES_CMAC.pyc and /dev/null differ
diff --git a/DataPayload.pyc b/DataPayload.pyc
deleted file mode 100644
index 4673f89..0000000
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diff --git a/Direction.pyc b/Direction.pyc
deleted file mode 100644
index f36eed0..0000000
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diff --git a/FHDR.pyc b/FHDR.pyc
deleted file mode 100644
index aae30b0..0000000
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diff --git a/JoinAcceptPayload.py b/JoinAcceptPayload.py
index 8fdd2a4..3e182ac 100644
--- a/JoinAcceptPayload.py
+++ b/JoinAcceptPayload.py
@@ -49,7 +49,7 @@ def get_rxdelay(self):
     def get_cflist(self):
         return self.cflist
 
-    def compute_mic(self, key, mhdr):
+    def compute_mic(self, key, direction, mhdr):
         mic = []
         mic += self.to_clear_raw()
         mic += [mhdr]
@@ -57,7 +57,7 @@ def compute_mic(self, key, mhdr):
         cmac = AES_CMAC()
         return cmac.encode(str(bytearray(key)), str(bytearray(mic)))[:4]
 
-    def decrypt_payload(self, key):
+    def decrypt_payload(self, key, direction):
         a = []
         a += self.encrypted_payload
         a += self.mic
diff --git a/JoinAcceptPayload.pyc b/JoinAcceptPayload.pyc
deleted file mode 100644
index 6b9aa0e..0000000
Binary files a/JoinAcceptPayload.pyc and /dev/null differ
diff --git a/JoinRequestPayload.py b/JoinRequestPayload.py
index 0505953..f77dd48 100644
--- a/JoinRequestPayload.py
+++ b/JoinRequestPayload.py
@@ -29,9 +29,12 @@ def get_deveui(self):
     def get_devnonce(self):
         return self.devnonce
 
-    def compute_mic(self, key, mhdr):
+    def compute_mic(self, key, direction, mhdr):
         mic = [mhdr]
         mic += self.to_raw()
 
         cmac = AES_CMAC()
         return cmac.encode(str(bytearray(key)), str(bytearray(mic)))[:4]
+
+    def decrypt_payload(self, key, direction):
+        return self.to_raw()
diff --git a/JoinRequestPayload.pyc b/JoinRequestPayload.pyc
deleted file mode 100644
index 5b746af..0000000
Binary files a/JoinRequestPayload.pyc and /dev/null differ
diff --git a/MType.pyc b/MType.pyc
deleted file mode 100644
index 7f7649a..0000000
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diff --git a/MacPayload.py b/MacPayload.py
index 1d1b4e5..b713b22 100644
--- a/MacPayload.py
+++ b/MacPayload.py
@@ -31,9 +31,7 @@ def __init__(self, mtype, mac_payload):
             self.frm_payload = DataPayload(self, mac_payload[self.fhdr.length() + 1:])
 
     def length(self):
-        if self.frm_payload == None:
-            return self.fhdr.length()
-        return self.fhdr.length() + 1 + self.frm_payload.length()
+        return len(self.to_raw())
 
     def to_raw(self):
         mac_payload = []
diff --git a/MacPayload.pyc b/MacPayload.pyc
deleted file mode 100644
index e627813..0000000
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diff --git a/MajorVersion.pyc b/MajorVersion.pyc
deleted file mode 100644
index 9d50334..0000000
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diff --git a/MalformedPacketException.pyc b/MalformedPacketException.pyc
deleted file mode 100644
index 59580f0..0000000
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diff --git a/PhyPayload.py b/PhyPayload.py
index 15673dd..4bfa1a3 100644
--- a/PhyPayload.py
+++ b/PhyPayload.py
@@ -9,11 +9,22 @@
 
 class PhyPayload:
 
-    def __init__(self, packet):
+    def __init__(self):
+        self.direction = Direction(Direction.UP)
+
+    def length(self):
+        return len(self.to_raw())
+
+    def to_raw(self):
+        phy_payload = [self.mhdr]
+        phy_payload += self.mac_payload.to_raw()
+        phy_payload += self.mic
+        return phy_payload
+
+    def packet(self, packet):
         if len(packet) < 12:
             raise MalformedPacketException("Invalid lorawan packet");
 
-        self.direction = Direction(Direction.UP)
         self.mhdr = packet[0]
         self.mversion = MajorVersion(self.mhdr)
         self.mtype = MType(self.mhdr)
@@ -51,20 +62,8 @@ def get_mic(self):
     def set_mic(self, mic):
         self.mic = mic
 
-    def to_raw(self):
-        phy_payload = [self.mhdr]
-        phy_payload += self.mac_payload.to_raw()
-        phy_payload += self.mic
-        return phy_payload
-
     def compute_mic(self, key):
         return self.mac_payload.frm_payload.compute_mic(key, self.get_direction(), self.get_mhdr())
 
-    def decrypt_payload(self, key):
+    def get_payload(self, key):
         return self.mac_payload.frm_payload.decrypt_payload(key, self.get_direction())
-
-    def encrypt_payload(self, key, data):
-        return self.mac_payload.frm_payload.encrypt_payload(key, self.get_direction(), data)
-
-    def set_payload(self, key, data):
-        return self.mac_payload.frm_payload.set_payload(key, self.get_direction(), data)
diff --git a/PhyPayload.pyc b/PhyPayload.pyc
deleted file mode 100644
index cfa82f5..0000000
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diff --git a/__init__.py b/__init__.py
index 19c46eb..dab818a 100644
--- a/__init__.py
+++ b/__init__.py
@@ -1,4 +1,7 @@
 from PhyPayload import PhyPayload
 
-def new(packet):
-  return PhyPayload(packet)
+def new(packet = None):
+    phy_payload = PhyPayload()
+    if packet:
+        phy_payload.packet(packet)
+    return phy_payload
diff --git a/__init__.pyc b/__init__.pyc
deleted file mode 100644
index d592269..0000000
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