double ratchet

double_ratchet.py

+#!/usr/bin/python
+# -*- coding: UTF-8 -*-
+
+import random
+
+class Msg:
+    def __init__(self, sender, rid, mid, dh):
+        self.sender = sender
+        self.rid = rid
+        self.mid = mid
+        self.dh = dh
+
+class Entity:
+    'A participant'
+
+    def __init__(self, name):
+        self.name = name
+        self.role = 'A' if (name == 'Alice') else 'B'
+        self.our_dh = [None,None]
+        self.their_dh = None
+        self.R = []
+        self.Ca = []
+        self.Cb = []
+        self.rid = 0
+        self.mid = 0
+        self.r_flag = False
+
+    def display(self):
+        print self.__dict__
+
+    def send(self):
+        if self.r_flag == True:
+            print self.name, '\tRatcheting...'
+            self.genDH()
+            self.rid+=1
+            self.mid=0
+            self.derive()
+            print self.name, '\tnext our_dh:', self.our_dh, 'key:', self.our_dh[1]+self.their_dh
+            self.r_flag = False
+        if self.role == 'A':
+            self.Ca[self.rid]['chain'].append(self.mid)
+        else:
+            self.Cb[self.rid]['chain'].append(self.mid)
+        toSend = Msg(self.name, self.rid, self.mid, self.our_dh[1])
+        self.mid+=1
+        print self.name, '\tsending: ', toSend.__dict__
+        return toSend
+
+    def receive(self, m):
+        print self.name, "\treceive: ", m.__dict__
+        if m.rid >= self.rid:
+            self.their_dh = m.dh
+            self.r_flag = True
+        print self.name, "\tkey: ", self.our_dh[1]+self.their_dh
+
+    def genDH(self):
+        self.our_dh = [random.randint(0,1024), random.randint(0,1024)]
+
+    def derive(self):
+        i = self.rid
+        self.R.append(i)
+        self.Ca.append({'rid':i,'chain':[]})
+        self.Cb.append({'rid':i,'chain':[]})
+
+def initialize():
+    print "Initializing"
+    a = Entity('Alice')
+    b = Entity('Bob')
+
+    b.our_dh = [random.randint(0,1024), random.randint(0,1024)]
+    a.our_dh = [random.randint(0,1024), random.randint(0,1024)]
+
+    b.derive()
+    b.r_flag = False
+
+    a.derive()
+    a.r_flag = True
+
+
+    a.their_dh = b.our_dh[1]
+    b.their_dh = a.our_dh[1]
+
+    return a, b
+
+a, b = initialize()
+a.receive(b.send())
+a.receive(b.send())
+a.receive(b.send())
+a.receive(b.send())
+b.receive(a.send())
+b.receive(a.send())
+b.receive(a.send())
+a.receive(b.send())
+a.receive(b.send())
+a.receive(b.send())
+a.receive(b.send())
+b.receive(a.send())
+b.receive(a.send())
+b.receive(a.send())