Added base code for stamp generation and validation

LXMF/LXMessage.py

@@ -4,6 +4,8 @@ import RNS.vendor.umsgpack as msgpack
 import os
 import time
 import base64
+import signal
+import multiprocessing
 
 from .LXMF import APP_NAME
 
@@ -224,15 +226,40 @@ class LXMessage:
     def register_failed_callback(self, callback):
         self.failed_callback = callback
 
+    @staticmethod
+    def stamp_workblock(message_id):
+        wb_st = time.time()
+        expand_rounds = 3000
+        workblock = b""
+        for n in range(expand_rounds):
+            workblock += RNS.Cryptography.hkdf(
+                length=256,
+                derive_from=message_id,
+                salt=RNS.Identity.full_hash(message_id+msgpack.packb(n)),
+                context=None,
+            )
+        wb_time = time.time() - wb_st
+        RNS.log(f"Stamp workblock size {RNS.prettysize(len(workblock))}, generated in {round(wb_time*1000,2)}ms", RNS.LOG_DEBUG)
+
+        return workblock
+
+    @staticmethod
+    def stamp_valid(stamp, target_cost, workblock):
+        target = 0b1 << 256-target_cost
+        result = RNS.Identity.full_hash(workblock+stamp)
+        if int.from_bytes(result, byteorder="big") > target:
+            return False
+        else:
+            return True
+
     def validate_stamp(self, target_cost):
         if self.stamp == None:
             return False
         else:
-            target = 0b1 << 256-target_cost
+            if LXMessage.stamp_valid(self.stamp, target_cost, LXMessage.stamp_workblock(self.message_id)):
-            if int.from_bytes(RNS.Identity.full_hash(self.message_id+self.stamp)) > target:
-                return False
-            else:
                 return True
+            else:
+                return False
 
     def get_stamp(self, timeout=None):
         if self.stamp_cost == None:
@@ -244,10 +271,23 @@ class LXMessage:
             return self.stamp
 
         else:
-            RNS.log(f"Generating stamp for {self}...", RNS.LOG_DEBUG)
+            RNS.log(f"Generating stamp with cost {self.stamp_cost} for {self}...", RNS.LOG_DEBUG)
+            workblock = LXMessage.stamp_workblock(self.message_id)
             start_time = time.time()
-            stamp = os.urandom(256//8); target = 0b1 << 256-self.stamp_cost; rounds = 1
+            total_rounds = 0
-            while int.from_bytes(RNS.Identity.full_hash(self.message_id+stamp)) > target:
+
+            stop_event   = multiprocessing.Event()
+            result_queue = multiprocessing.Queue(maxsize=1)
+            rounds_queue = multiprocessing.Queue()
+            def job(stop_event):
+                terminated = False
+                rounds = 0
+
+                stamp = os.urandom(256//8)
+                while not LXMessage.stamp_valid(stamp, self.stamp_cost, workblock):
+                    if stop_event.is_set():
+                        break
+
                     if timeout != None and rounds % 10000 == 0:
                         if time.time() > start_time + timeout:
                             RNS.log(f"Stamp generation for {self} timed out", RNS.LOG_ERROR)
@@ -256,7 +296,35 @@ class LXMessage:
                     stamp = os.urandom(256//8)
                     rounds += 1
 
-            RNS.log(f"Stamp generated in {RNS.prettytime(time.time() - start_time)}", RNS.LOG_DEBUG)
+                rounds_queue.put(rounds)
+                if not stop_event.is_set():
+                    result_queue.put(stamp)
+
+            job_procs = []
+            jobs = multiprocessing.cpu_count()
+            for _ in range(jobs):
+                process = multiprocessing.Process(target=job, kwargs={"stop_event": stop_event},)
+                job_procs.append(process)
+                process.start()
+
+            stamp = result_queue.get()
+            stop_event.set()
+
+            for j in range(jobs):
+                process = job_procs[j]
+                process.join()
+                total_rounds += rounds_queue.get()
+
+            duration = time.time() - start_time
+            rounds = total_rounds
+
+            # TODO: Remove stats output
+            RNS.log(f"Stamp generated in {RNS.prettytime(duration)} / {rounds} rounds", RNS.LOG_DEBUG)
+            RNS.log(f"Rounds per second {int(rounds/duration)}", RNS.LOG_DEBUG)
+            RNS.log(f"Stamp: {RNS.hexrep(stamp)}", RNS.LOG_DEBUG)
+            RNS.log(f"Resulting hash: {RNS.hexrep(RNS.Identity.full_hash(workblock+stamp))}", RNS.LOG_DEBUG)
+            ###########################
+
             return stamp
 
     def pack(self):

docs/example_receiver.py

@@ -13,6 +13,12 @@ def delivery_callback(message):
     if message.unverified_reason == LXMF.LXMessage.SOURCE_UNKNOWN:
       signature_string = "Cannot verify, source is unknown"
 
+  stamp_cost = 12
+  if message.validate_stamp(stamp_cost):
+    stamp_string = "Valid"
+  else:
+    stamp_string = "Not valid"
+
   RNS.log("\t+--- LXMF Delivery ---------------------------------------------")
   RNS.log("\t| Source hash            : "+RNS.prettyhexrep(message.source_hash))
   RNS.log("\t| Source instance        : "+str(message.get_source()))
@@ -24,6 +30,7 @@ def delivery_callback(message):
   RNS.log("\t| Content                : "+message.content_as_string())
   RNS.log("\t| Fields                 : "+str(message.fields))
   RNS.log("\t| Message signature      : "+signature_string)
+  RNS.log("\t| Stamp                  : "+stamp_string)
   RNS.log("\t+---------------------------------------------------------------")
 
 r = RNS.Reticulum()