diff --git a/beacon/beacon_chain_node.py b/beacon/beacon_chain_node.py
new file mode 100644
index 0000000..79924a4
--- /dev/null
+++ b/beacon/beacon_chain_node.py
@@ -0,0 +1,297 @@
+import os
+from binascii import hexlify
+from Crypto.Hash import keccak
+import random
+
+def to_hex(s):
+    return hexlify(s).decode('utf-8')
+
+memo = {}
+
+def sha3(x):
+    if x not in memo:
+        memo[x] = keccak.new(digest_bits=256, data=x).digest()
+    return memo[x]
+
+def hash_to_int(h):
+    o = 0
+    for c in h:
+        o = (o << 8) + c
+    return o
+
+NOTARIES = 40
+BASE_TS_DIFF = 1
+SKIP_TS_DIFF = 6
+SAMPLE = 9
+MIN_SAMPLE = 5
+POWDIFF = 30 * NOTARIES
+
+def checkpow(work, nonce):
+    # Discrete log PoW, lolz
+    # Quadratic nonresidues only
+    return pow(work, nonce, 65537) * POWDIFF < 65537 * 2 and pow(nonce, 32768, 65537) == 65536
+
+class MainChainBlock():
+    def __init__(self, parent, pownonce, ts):
+        self.parent_hash = parent.hash if parent else (b'\x00' * 32)
+        assert isinstance(self.parent_hash, bytes)
+        self.hash = sha3(self.parent_hash + str(pownonce).encode('utf-8'))
+        self.ts = ts
+        if parent:
+            assert checkpow(parent.pownonce, pownonce)
+            assert self.ts >= parent.ts
+        self.pownonce = pownonce
+        self.number = 0 if parent is None else parent.number + 1
+            
+
+# Not a full RANDAO; stub for now
+class BeaconBlock():
+    def __init__(self, parent, proposer, ts, sigs, main_chain_ref):
+        self.contents = os.urandom(32)
+        self.parent_hash = parent.hash if parent else (b'\x11' * 32)
+        self.hash = sha3(self.parent_hash + self.contents)
+        self.ts = ts
+        self.sigs = sigs
+        self.number = parent.number + 1 if parent else 0
+        self.main_chain_ref = main_chain_ref if main_chain_ref else parent.main_chain_ref
+
+        if parent:
+            i = parent.child_proposers.index(proposer)
+            assert self.ts >= parent.ts + BASE_TS_DIFF + i * SKIP_TS_DIFF
+            assert len(sigs) >= parent.notary_req
+            for sig in sigs:
+                assert sig.target_hash == self.parent_hash
+
+        # Calculate child proposers
+        v = hash_to_int(sha3(self.contents))
+        self.child_proposers = []
+        while v > 0:
+            self.child_proposers.append(v % NOTARIES)
+            v //= NOTARIES
+
+        # Calculate notaries
+        first = parent and proposer == parent.child_proposers[0]
+        self.notary_req = 0 if first else MIN_SAMPLE
+        v = hash_to_int(sha3(self.contents + b':n'))
+        self.notaries = []
+        for i in range(SAMPLE if first else SAMPLE):
+            self.notaries.append(v % NOTARIES)
+            v //= NOTARIES
+
+
+class Sig():
+    def __init__(self, proposer, target):
+        self.proposer = proposer
+        self.target_hash = target.hash
+        self.hash = os.urandom(32)
+        assert self.proposer in target.notaries
+
+main_genesis = MainChainBlock(None, 59049, 0)
+beacon_genesis = BeaconBlock(None, 1, 0, [], main_genesis.hash)
+
+class BlockMakingRequest():
+    def __init__(self, parent, ts):
+        self.parent = parent
+        self.ts = ts
+        self.hash = os.urandom(32)
+
+class Node():
+
+    def __init__(self, _id, network, sleepy=False, careless=False):
+        self.blocks = {beacon_genesis.hash: beacon_genesis, main_genesis.hash: main_genesis}
+        self.sigs = {}
+        self.beacon_head = beacon_genesis.hash
+        self.main_chain = [main_genesis.hash]
+        self.timequeue = []
+        self.parentqueue = {}
+        self.children = {}
+        self.ts = 0
+        self.id = _id
+        self.network = network
+        self.used_parents = {}
+        self.processed = {}
+        self.sleepy = sleepy
+        self.careless = careless
+
+    def broadcast(self, x):
+        if self.sleepy and self.ts:
+            return
+        #self.log("Broadcasting %s %s" % ("block" if isinstance(x, BeaconBlock) else "sig", to_hex(x.hash[:4])))
+        self.network.broadcast(self, x)
+        self.on_receive(x)
+
+    def log(self, words, lvl=3, all=False):
+        #if "Tick:" != words[:5] or self.id == 0:
+        if (self.id == 0 or all) and lvl >= 2:
+            print(self.id, words)
+
+    def on_receive(self, obj, reprocess=False):
+        if obj.hash in self.processed and not reprocess:
+            return
+        self.processed[obj.hash] = True
+        #self.log("Processing %s %s" % ("block" if isinstance(obj, BeaconBlock) else "sig", to_hex(obj.hash[:4])))
+        if isinstance(obj, BeaconBlock):
+            return self.on_receive_block(obj)
+        elif isinstance(obj, MainChainBlock):
+            return self.on_receive_main_block(obj)
+        elif isinstance(obj, Sig):
+            return self.on_receive_sig(obj)
+        elif isinstance(obj, BlockMakingRequest):
+            if self.beacon_head == obj.parent:
+                mc_ref = self.blocks[obj.parent]
+                for i in range(2):
+                    if mc_ref.number == 0:
+                        break
+                    #mc_ref = self.blocks[mc_ref].parent_hash
+                x = BeaconBlock(self.blocks[obj.parent], self.id, self.ts,
+                                self.sigs[obj.parent] if obj.parent in self.sigs else [],
+                                self.main_chain[-1])
+                self.log("Broadcasting block %s" % to_hex(x.hash[:4]))
+                self.broadcast(x)
+
+    def add_to_timequeue(self, obj):
+        i = 0
+        while i < len(self.timequeue) and self.timequeue[i].ts < obj.ts: 
+            i += 1
+        self.timequeue.insert(i, obj)
+
+    def on_receive_main_block(self, block):
+        # Parent not yet received
+        if block.parent_hash not in self.blocks:
+            if block.parent_hash not in self.parentqueue:
+                self.parentqueue[block.parent_hash] = []
+            self.parentqueue[block.parent_hash].append(block)
+            return None
+        self.log("Processing main chain block %s" % to_hex(block.hash[:4]))
+        self.blocks[block.hash] = block
+        # Reorg the main chain if new head
+        if block.number > self.blocks[self.main_chain[-1]].number:
+            assert block.number == len(self.main_chain), (block.number, self.blocks[self.main_chain[-1]].number)
+            reorging = (block.parent_hash != self.main_chain[-1])
+            if reorging:
+                self.log("Reorging main chain", all=True)
+            i, c = block.number - 1, block.parent_hash
+            while c != self.main_chain[i]:
+                self.main_chain[i] = c
+                c = self.blocks[c].parent_hash
+                i -= 1
+            self.main_chain.append(block.hash)
+            for i in range(len(self.main_chain)):
+                assert self.blocks[self.main_chain[i]].number == i
+            # Reorg the beacon
+            if reorging:
+                pre_beacon = self.beacon_head
+                while self.blocks[self.beacon_head].main_chain_ref not in self.main_chain:
+                    self.beacon_head = self.blocks[self.beacon_head].parent_hash
+                descendant_queue = [self.beacon_head]
+                while len(descendant_queue):
+                    first = descendant_queue.pop(0)
+                    if first in self.children:
+                        for c in self.children[first]:
+                            if isinstance(self.blocks[c], BeaconBlock) and self.blocks[c].main_chain_ref in self.main_chain:
+                                descendant_queue.append(c)
+                    if self.blocks[first].number > self.blocks[self.beacon_head].number:
+                        self.beacon_head = first
+                if self.beacon_head != pre_beacon:
+                    self.log("Reorged beacon due to main chain reorg", all=True)
+        # Add child record
+        if block.parent_hash not in self.children:
+            self.children[block.parent_hash] = []
+        self.children[block.parent_hash].append(block.hash)
+        # Check for children
+        if block.hash in self.parentqueue:
+            for b in self.parentqueue[block.hash]:
+                self.on_receive(b, reprocess=True)
+            del self.parentqueue[block.hash]
+        self.network.broadcast(self, block)
+
+    def is_descendant(self, a, b):
+        a, b = self.blocks[a], self.blocks[b]
+        while b.number > a.number:
+            b = self.blocks[b.parent_hash]
+        return a.hash == b.hash
+
+    def on_receive_block(self, block):
+        # Parent not yet received
+        if block.parent_hash not in self.blocks:
+            if block.parent_hash not in self.parentqueue:
+                self.parentqueue[block.parent_hash] = []
+            self.parentqueue[block.parent_hash].append(block)
+            return None
+        # Main chain parent not yet received
+        if block.main_chain_ref not in self.blocks:
+            if block.main_chain_ref not in self.parentqueue:
+                self.parentqueue[block.main_chain_ref] = []
+            self.parentqueue[block.main_chain_ref].append(block)
+            return None
+        # Too early
+        if block.ts > self.ts:
+            self.add_to_timequeue(block)
+            return
+        assert block.parent_hash in self.blocks
+        assert block.main_chain_ref in self.blocks
+        assert self.blocks[block.parent_hash].main_chain_ref in self.blocks
+        # Check consistency of cross-link reference
+        assert self.is_descendant(self.blocks[block.parent_hash].main_chain_ref, block.main_chain_ref)
+        # Add the block
+        self.log("Processing beacon block %s" % to_hex(block.hash[:4]))
+        self.blocks[block.hash] = block
+        # Am I a notary, and is the block building on the head?
+        # careless = I notarize even stuff not on the head
+        if block.parent_hash == self.beacon_head or self.careless:
+            if self.id in block.notaries:
+                # Then broadcast a signature
+                self.broadcast(Sig(self.id, block))
+        # Check for sigs, add to head?, make a block?
+        if (block.hash in self.sigs and len(self.sigs[block.hash]) >= block.notary_req) or block.notary_req == 0:
+            if block.number > self.blocks[self.beacon_head].number and block.main_chain_ref in self.main_chain:
+                self.log("Changed head: %s" % block.number)
+                self.beacon_head = block.hash
+            if self.id in self.blocks[block.hash].child_proposers:
+                my_index = self.blocks[block.hash].child_proposers.index(self.id)
+                target_ts = block.ts + BASE_TS_DIFF + my_index * SKIP_TS_DIFF
+                self.log("Making block request for %.1f" % target_ts)
+                self.add_to_timequeue(BlockMakingRequest(block.hash, target_ts))
+        # Add child record
+        if block.parent_hash not in self.children:
+            self.children[block.parent_hash] = []
+        self.children[block.parent_hash].append(block.hash)
+        # Check for children
+        if block.hash in self.parentqueue:
+            for b in self.parentqueue[block.hash]:
+                self.on_receive(b, reprocess=True)
+            del self.parentqueue[block.hash]
+        # Rebroadcast
+        self.network.broadcast(self, block)
+
+    def on_receive_sig(self, sig):
+        self.log("Processing sig for %s" % to_hex(sig.target_hash[:4]), lvl=1)
+        if sig.target_hash not in self.sigs:
+            self.sigs[sig.target_hash] = []
+        self.sigs[sig.target_hash].append(sig)
+        # Add to head? Make a block?
+        if sig.target_hash in self.blocks and len(self.sigs[sig.target_hash]) == self.blocks[sig.target_hash].notary_req:
+            block = self.blocks[sig.target_hash]
+            if block.number > self.blocks[self.beacon_head].number and block.main_chain_ref in self.main_chain:
+                self.log("Changed head: %s" % block.number)
+                self.beacon_head = block.hash
+            if self.id in block.child_proposers:
+                my_index = block.child_proposers.index(self.id)
+                target_ts = block.ts + BASE_TS_DIFF + my_index * SKIP_TS_DIFF
+                self.log("Making block request for %.1f" % target_ts)
+                self.add_to_timequeue(BlockMakingRequest(block.hash, target_ts))
+        # Rebroadcast
+        self.network.broadcast(self, sig)
+
+    def tick(self):
+        if self.ts == 0:
+            if self.id in beacon_genesis.notaries:
+                self.broadcast(Sig(self.id, beacon_genesis))
+        self.ts += 0.1
+        self.log("Tick: %.1f" % self.ts, lvl=1)
+        while len(self.timequeue) and self.timequeue[0].ts <= self.ts:
+            self.on_receive(self.timequeue.pop(0))
+        pownonce = random.randrange(65537)
+        mchead = self.blocks[self.main_chain[-1]]
+        if checkpow(mchead.pownonce, pownonce):
+            self.broadcast(MainChainBlock(mchead, pownonce, self.ts))
diff --git a/beacon/distributions.py b/beacon/distributions.py
new file mode 100644
index 0000000..6412e3d
--- /dev/null
+++ b/beacon/distributions.py
@@ -0,0 +1,37 @@
+import random, sys
+
+
+def normal_distribution(mean, standev):
+    def f():
+        return int(random.normalvariate(mean, standev))
+
+    return f
+
+
+def exponential_distribution(mean):
+    def f():
+        total = 0
+        while 1:
+            total += 1
+            if not random.randrange(32):
+                break
+        return int(total * 0.03125 * mean)
+
+    return f
+
+
+def convolve(*args):
+    def f():
+        total = 0
+        for arg in args:
+            total += arg()
+        return total
+
+    return f
+
+
+def transform(dist, xformer):
+    def f():
+        return xformer(dist())
+
+    return f
diff --git a/beacon/networksim.py b/beacon/networksim.py
new file mode 100644
index 0000000..2415262
--- /dev/null
+++ b/beacon/networksim.py
@@ -0,0 +1,75 @@
+from distributions import transform, normal_distribution
+import random
+
+
+class NetworkSimulator():
+
+    def __init__(self, latency=50):
+        self.agents = []
+        self.latency_distribution_sample = transform(normal_distribution(latency, (latency * 2) // 5), lambda x: max(x, 0))
+        self.time = 0
+        self.objqueue = {}
+        self.peers = {}
+        self.reliability = 0.9
+
+    def generate_peers(self, num_peers=5):
+        self.peers = {}
+        for a in self.agents:
+            p = []
+            while len(p) <= num_peers // 2:
+                p.append(random.choice(self.agents))
+                if p[-1] == a:
+                    p.pop()
+            self.peers[a.id] = self.peers.get(a.id, []) + p
+            for peer in p:
+                self.peers[peer.id] = self.peers.get(peer.id, []) + [a]
+
+    def tick(self):
+        if self.time in self.objqueue:
+            for recipient, obj in self.objqueue[self.time]:
+                if random.random() < self.reliability:
+                    recipient.on_receive(obj)
+            del self.objqueue[self.time]
+        for a in self.agents:
+            a.tick()
+        self.time += 1
+
+    def run(self, steps):
+        for i in range(steps):
+            self.tick()
+
+    def broadcast(self, sender, obj):
+        for p in self.peers[sender.id]:
+            recv_time = self.time + self.latency_distribution_sample()
+            if recv_time not in self.objqueue:
+                self.objqueue[recv_time] = []
+            self.objqueue[recv_time].append((p, obj))
+
+    def direct_send(self, to_id, obj):
+        for a in self.agents:
+            if a.id == to_id:
+                recv_time = self.time + self.latency_distribution_sample()
+                if recv_time not in self.objqueue:
+                    self.objqueue[recv_time] = []
+                self.objqueue[recv_time].append((a, obj))
+
+    def knock_offline_random(self, n):
+        ko = {}
+        while len(ko) < n:
+            c = random.choice(self.agents)
+            ko[c.id] = c
+        for c in ko.values():
+            self.peers[c.id] = []
+        for a in self.agents:
+            self.peers[a.id] = [x for x in self.peers[a.id] if x.id not in ko]
+
+    def partition(self):
+        a = {}
+        while len(a) < len(self.agents) / 2:
+            c = random.choice(self.agents)
+            a[c.id] = c
+        for c in self.agents:
+            if c.id in a:
+                self.peers[c.id] = [x for x in self.peers[c.id] if x.id in a]
+            else:
+                self.peers[c.id] = [x for x in self.peers[c.id] if x.id not in a]
diff --git a/beacon/test.py b/beacon/test.py
new file mode 100644
index 0000000..cb112b3
--- /dev/null
+++ b/beacon/test.py
@@ -0,0 +1,68 @@
+from networksim import NetworkSimulator
+from beacon_chain_node import Node, NOTARIES, BeaconBlock, MainChainBlock, main_genesis, beacon_genesis
+
+net = NetworkSimulator(latency=15)
+notaries = [Node(i, net, sleepy=i % 5 == 9) for i in range(NOTARIES)]
+net.agents = notaries
+net.generate_peers()
+for i in range(2000):
+    net.tick()
+for n in notaries:
+    print("Beacon head: %d" % n.blocks[n.beacon_head].number)
+    print("Main chain head: %d" % n.blocks[n.main_chain[-1]].number)
+    print("Total beacon blocks received: %d" % (len([b for b in n.blocks.values() if isinstance(b, BeaconBlock)]) - 1))
+    print("Total beacon blocks received and signed: %d" % (len([b for b in n.blocks.keys() if b in n.sigs and len(n.sigs[b]) >= n.blocks[b].notary_req]) - 1))
+    print("Total main chain blocks received: %d" % (len([b for b in n.blocks.values() if isinstance(b, MainChainBlock)]) - 1))
+
+import matplotlib.pyplot as plt
+import networkx as nx
+import random
+
+G=nx.Graph()
+
+#positions = {main_genesis.hash: 0, beacon_genesis.hash: 0}
+#queue = [
+
+for b in n.blocks.values():
+    if b.number > 0:
+        if isinstance(b, BeaconBlock):
+            G.add_edge(b.hash, b.main_chain_ref, color='g')
+            G.add_edge(b.hash, b.parent_hash, color='y')
+        else:
+            G.add_edge(b.hash, b.parent_hash, color='b')
+        
+#G.add_edge('a','b',weight=1)
+#G.add_edge('a','c',weight=1)
+#G.add_edge('a','d',weight=1)
+#G.add_edge('a','e',weight=1)
+#G.add_edge('a','f',weight=1)
+#G.add_edge('a','g',weight=1)
+
+# pos=nx.spring_layout(G)
+ypos={main_genesis.hash: 0, beacon_genesis.hash: 0}
+queue = n.children[main_genesis.hash] + n.children[beacon_genesis.hash]
+while len(queue):
+    first = queue.pop(0)
+    if isinstance(n.blocks[first], MainChainBlock):
+        if n.blocks[first].parent_hash not in ypos:
+            queue.append(first)
+            continue
+        ypos[first] = ypos[n.blocks[first].parent_hash] + 10
+    elif isinstance(n.blocks[first], BeaconBlock):
+        if n.blocks[first].parent_hash not in ypos or n.blocks[first].main_chain_ref not in ypos:
+            queue.append(first)
+            continue
+        ypos[first] = max(ypos[n.blocks[first].parent_hash] + 1, ypos[n.blocks[first].main_chain_ref] + 1)
+    if first in n.children:
+        queue.extend(n.children[first])
+pos={b.hash: (b.ts + random.randrange(5) + (5 if isinstance(b, MainChainBlock) else 0), b.ts) for b in n.blocks.values()}
+edges = G.edges()
+colors = [G[u][v]['color'] for u,v in edges]
+nx.draw_networkx_nodes(G,pos,node_size=10,node_shape='o',node_color='0.75')
+
+nx.draw_networkx_edges(G,pos,
+                width=2,edge_color=colors)
+
+plt.axis('off')
+# plt.savefig("degree.png", bbox_inches="tight")
+plt.show()