Announce and validation

FPE/Destination.py

@@ -162,4 +162,18 @@ class Destination:
 	# Creates an announce packet for this destination.
 	# Application specific data can be added to the announce.
 	def announce(self,app_data=None):
-		pass
+		destination_hash = self.hash
+		random_hash = self.identity.getRandomHash()
+		
+		signed_data = self.hash+self.identity.getPublicKey()+random_hash
+		if app_data != None:
+			signed_data += app_data
+
+		signature = self.identity.sign(signed_data)
+
+		announce_data = self.hash+self.identity.getPublicKey()+random_hash+signature
+		if app_data != None:
+			announce_data += app_data
+
+		FPE.Packet(self, announce_data, FPE.Packet.ANNOUNCE).send()
+

FPE/FlexPE.py

@@ -1,6 +1,4 @@
 from Interfaces import *
-import FPE
-
 import ConfigParser
 import jsonpickle
 from vendor.configobj import ConfigObj
@@ -9,8 +7,10 @@ import array
 import os.path
 import os
 
+import FPE
+
 class FlexPE:
-	MTU          = 600
+	MTU          = 500
 	router       = None
 	config       = None
 	destinations = []
@@ -18,6 +18,7 @@ class FlexPE:
 	configdir = os.path.expanduser("~")+"/.flexpe"
 	configpath   = configdir+"/config"
 
+	packetlist = []
 
 	def __init__(self,config=None):
 		if config != None:
@@ -42,12 +43,20 @@ class FlexPE:
 
 	@staticmethod
 	def incoming(data):
-		packet = FPE.Packet(None, data)
-		packet.unpack()
+		packet_hash = FPE.Identity.fullHash(data)
 
-		for destination in FlexPE.destinations:
-			if destination.hash == packet.destination_hash and destination.type == packet.destination_type:
-				destination.receive(packet.data)
+		if not packet_hash in FlexPE.packetlist:
+			FlexPE.packetlist.append(packet_hash)
+			packet = FPE.Packet(None, data)
+			packet.unpack()
+
+			if packet.packet_type == FPE.Packet.ANNOUNCE:
+				FPE.Identity.validateAnnounce(packet)
+			
+			if packet.packet_type == FPE.Packet.RESOURCE:
+				for destination in FlexPE.destinations:
+					if destination.hash == packet.destination_hash and destination.type == packet.destination_type:
+						destination.receive(packet.data)
 
 	@staticmethod
 	def outbound(raw):

FPE/Identity.py

@@ -1,19 +1,26 @@
 import base64
 import math
+import os
 import FPE
 from cryptography.hazmat.primitives import hashes
 from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.serialization import load_der_public_key
+from cryptography.hazmat.primitives.serialization import load_der_private_key
 from cryptography.hazmat.primitives.asymmetric import rsa
 from cryptography.hazmat.primitives.asymmetric import padding
 
 class Identity:
 	# Configure key size
 	KEYSIZE    = 1536;
+	DERKEYSIZE = 1808;
 
 	# Padding size, not configurable
 	PADDINGSIZE= 336;
 
+	# Storage
+	remembered_destinations = {}
+
 	def __init__(self):
 		# Initialize keys to none
 		self.prv = None
@@ -26,12 +33,53 @@ class Identity:
 		self.createKeys()
 
 	@staticmethod
-	def getHash(pub_key):
+	def remember(hash, public_key, app_data = None):
+		FPE.log("Remembering "+FPE.hexrep(hash, False), FPE.LOG_VERBOSE)
+		Identity.remembered_destinations[hash] = [public_key, app_data]
+
+	@staticmethod
+	def recall(identity):
+		pass
+
+	@staticmethod
+	def fullHash(data):
 		digest = hashes.Hash(hashes.SHA256(), backend=default_backend())
-		digest.update(pub_key)
+		digest.update(data)
+
+		return digest.finalize()
+
+	@staticmethod
+	def truncatedHash(data):
+		digest = hashes.Hash(hashes.SHA256(), backend=default_backend())
+		digest.update(data)
 
 		return digest.finalize()[:10]
 
+	@staticmethod
+	def validateAnnounce(packet):
+		if packet.packet_type == FPE.Packet.ANNOUNCE:
+			FPE.log("Validating announce from "+FPE.hexrep(packet.destination_hash), FPE.LOG_VERBOSE)
+			destination_hash = packet.destination_hash
+			public_key = packet.data[10:Identity.DERKEYSIZE/8+10]
+			random_hash = packet.data[Identity.DERKEYSIZE/8+10:Identity.DERKEYSIZE/8+20]
+			signature = packet.data[Identity.DERKEYSIZE/8+20:Identity.DERKEYSIZE/8+20+Identity.KEYSIZE/8]
+			app_data = ""
+			if len(packet.data) > Identity.DERKEYSIZE/8+20+Identity.KEYSIZE/8:
+				app_data = packet.data[Identity.DERKEYSIZE/8+20+Identity.KEYSIZE/8:]
+
+			signed_data = destination_hash+public_key+random_hash+app_data
+
+			announced_identity = Identity()
+			announced_identity.loadPublicKey(public_key)
+
+			if announced_identity.validate(signature, signed_data):
+				FPE.log("Announce is valid", FPE.LOG_VERBOSE)
+				FPE.Identity.remember(destination_hash, public_key)
+			else:
+				FPE.log("Announce is invalid", FPE.LOG_VERBOSE)
+
+			del announced_identity
+
 	def createKeys(self):
 		self.prv = rsa.generate_private_key(
 			public_exponent=65337,
@@ -49,7 +97,7 @@ class Identity:
 			format=serialization.PublicFormat.SubjectPublicKeyInfo
 		)
 
-		self.hash = Identity.getHash(self.pub_bytes)
+		self.hash = Identity.truncatedHash(self.pub_bytes)
 		self.hexhash = self.hash.encode("hex_codec")
 
 		FPE.log("Identity keys created, private length is "+str(len(self.prv_bytes))+" public length is "+str(len(self.pub_bytes)), FPE.LOG_INFO)
@@ -150,5 +198,24 @@ class Identity:
 		else:
 			raise KeyError("Signing failed because identity does not hold a private key")
 
-	def announce(self):
-		pass
+	def validate(self, signature, message):
+		if self.pub != None:
+			try:
+				self.pub.verify(
+					signature,
+					message,
+					padding.PSS(
+						mgf=padding.MGF1(hashes.SHA256()),
+						salt_length=padding.PSS.MAX_LENGTH
+					),
+					hashes.SHA256()
+				)
+				return True
+			except:
+				return False
+		else:
+			raise KeyError("Signature validation failed because identity does not hold a public key")
+
+	def getRandomHash(self):
+		return self.truncatedHash(os.urandom(10))
+

FPE/Packet.py

@@ -3,11 +3,11 @@ import FPE
 
 class Packet:
 	# Constants
-	MESSAGE      = 0x00;
-	RESOURCE     = 0x01;
+	RESOURCE     = 0x00;
+	ANNOUNCE     = 0x01;
 	LINKREQUEST  = 0x02;
 	PROOF        = 0x03;
-	types        = [MESSAGE, RESOURCE, LINKREQUEST, PROOF]
+	types        = [RESOURCE, ANNOUNCE, LINKREQUEST, PROOF]
 
 	HEADER_1     = 0x00;	# Normal header format
 	HEADER_2     = 0x01;	# Header format used for link packets in transport
@@ -15,7 +15,7 @@ class Packet:
 	HEADER_4     = 0x03;	# Reserved
 	header_types = [HEADER_1, HEADER_2, HEADER_3, HEADER_4]
 
-	def __init__(self, destination, data, packet_type = MESSAGE, transport_type = None, header_type = HEADER_1, transport_id = None):
+	def __init__(self, destination, data, packet_type = RESOURCE, transport_type = FPE.Transport.BROADCAST, header_type = HEADER_1, transport_id = None):
 		if destination != None:
 			if transport_type == None:
 				transport_type = FPE.Transport.BROADCAST
@@ -53,7 +53,11 @@ class Packet:
 				raise IOError("Packet with header type 2 must have a transport ID")
 
 		self.header += self.destination.hash
-		self.ciphertext = self.destination.encrypt(self.data)
+		if self.packet_type != Packet.ANNOUNCE:
+			self.ciphertext = self.destination.encrypt(self.data)
+		else:
+			self.ciphertext = self.data
+
 		self.raw = self.header + self.ciphertext
 
 		if len(self.raw) > self.MTU:

FPE/__init__.py

@@ -58,3 +58,13 @@ def log(msg, level=3):
 			file = open(logfile, "a")
 			file.write(logstring+"\n")
 			file.close()
+
+def hexprint(data):
+	print(hexrep(hexrep))
+
+def hexrep(data, delimit=True):
+	delimiter = ":"
+	if not delimit:
+		delimiter = ""
+	hexrep = delimiter.join("{:02x}".format(ord(c)) for c in data)
+	return hexrep

t.py

@@ -19,30 +19,16 @@ identity = Identity()
 d1=Destination(identity, Destination.IN, Destination.SINGLE, "messenger", "user")
 d1.setCallback(testCallback)
 
-d2=Destination(identity, Destination.IN, Destination.PLAIN, "messenger", "user")
-d2.setCallback(testCallback)
-
-# d2=Destination(identity, Destination.IN, Destination.PLAIN, "plainchat", "markqvist")
-# d2.setCallback(testCallback)
-
-#print identity.hexhash
-#print d1.name
-#print d1.hexhash
-#print d1.identity.pub
-#print "---"
-#print
-
 msg=""
 for x in range(300):
 	msg += "a"
 signed = d1.sign(msg)
 sl = len(signed)
 pl = len(d1.identity.pub_bytes)
-#print("Signature length is "+str(sl))
-#print("Minimum announce is "+str(pl+sl+8))
 
+d1.announce()
 p1=Packet(d1, msg)
-p1.send()
+#p1.send()
 
 # p2=Packet(d2,"Test af msg")
 # p2.send()