From 97b8b3b32a73218c96c4f43479ca0ece4a48d81d Mon Sep 17 00:00:00 2001
From: chris-belcher <chris-belcher@users.noreply.github.com>
Date: Wed, 14 Apr 2021 15:48:31 +0100
Subject: [PATCH] Show fidelity bonds on orderbook watch html page

Add two new pages for the orderbook watch html server. One displays
each fidelity bond individually, the other shows calculations about
how expensive a successful sybil attack would be against the current
fidelity bonds in the orderbook.
---
 scripts/obwatch/ob-watcher.py                | 368 +++++++++++++++++--
 scripts/obwatch/orderbook.html               |   2 +
 scripts/obwatch/sybil_attack_calculations.py |  81 ++++
 3 files changed, 423 insertions(+), 28 deletions(-)
 create mode 100755 scripts/obwatch/sybil_attack_calculations.py

diff --git a/scripts/obwatch/ob-watcher.py b/scripts/obwatch/ob-watcher.py
index b0cdc84..fe6cf7e 100755
--- a/scripts/obwatch/ob-watcher.py
+++ b/scripts/obwatch/ob-watcher.py
@@ -16,12 +16,18 @@ from future.moves.urllib.parse import parse_qs
 from decimal import Decimal
 from optparse import OptionParser
 from twisted.internet import reactor
+from datetime import datetime
 
 if sys.version_info < (3, 7):
     print("ERROR: this script requires at least python 3.7")
     exit(1)
 
 from jmbase.support import EXIT_FAILURE
+from jmbase import bintohex
+from jmclient import FidelityBondMixin, get_interest_rate
+from jmclient.fidelity_bond import FidelityBondProof
+
+import sybil_attack_calculations as sybil
 
 from jmbase import get_log
 log = get_log()
@@ -86,31 +92,45 @@ def cjfee_display(cjfee, order, btc_unit, rel_unit):
         return str(Decimal(cjfee) * Decimal(rel_unit_to_factor[rel_unit])) + rel_unit
 
 
-def satoshi_to_unit(sat, order, btc_unit, rel_unit):
-    power = unit_to_power[btc_unit]
+def satoshi_to_unit_power(sat, power):
     return ("%." + str(power) + "f") % float(
         Decimal(sat) / Decimal(10 ** power))
 
+def satoshi_to_unit(sat, order, btc_unit, rel_unit):
+    return satoshi_to_unit_power(sat, unit_to_power[btc_unit])
 
 def order_str(s, order, btc_unit, rel_unit):
     return str(s)
 
 
-def create_table_heading(btc_unit, rel_unit):
+def create_offerbook_table_heading(btc_unit, rel_unit):
     col = '  <th>{1}</th>\n'  # .format(field,label)
     tableheading = '<table class="tftable sortable" border="1">\n <tr>' + ''.join(
             [
-                col.format('ordertype', 'Type'), col.format(
-                    'counterparty', 'Counterparty'),
+                col.format('ordertype', 'Type'),
+                col.format('counterparty', 'Counterparty'),
                 col.format('oid', 'Order ID'),
-                col.format('cjfee', 'Fee'), col.format(
-                    'txfee', 'Miner Fee Contribution / ' + btc_unit),
-                col.format(
-                        'minsize', 'Minimum Size / ' + btc_unit), col.format(
-                    'maxsize', 'Maximum Size / ' + btc_unit)
+                col.format('cjfee', 'Fee'),
+                col.format('txfee', 'Miner Fee Contribution / ' + btc_unit),
+                col.format('minsize', 'Minimum Size / ' + btc_unit),
+                col.format('maxsize', 'Maximum Size / ' + btc_unit),
+                col.format('bondvalue', 'Bond value / ' + btc_unit + '&#xb2;')
             ]) + ' </tr>'
     return tableheading
 
+def create_bonds_table_heading(btc_unit):
+    tableheading = ('<table class="tftable sortable" border="1"><tr>'
+        + '<th>Counterparty</th>'
+        + '<th>UTXO</th>'
+        + '<th>Bond value / ' + btc_unit + '&#xb2;</th>'
+        + '<th>Locktime</th>'
+        + '<th>Locked coins / ' + btc_unit + '</th>'
+        + '<th>Confirmation time</th>'
+        + '<th>Signature expiry height</th>'
+        + '<th>Redeem script</th>'
+        + '</tr>'
+    )
+    return tableheading
 
 def create_choose_units_form(selected_btc, selected_rel):
     choose_units_form = (
@@ -128,6 +148,53 @@ def create_choose_units_form(selected_btc, selected_rel):
             '<option selected="selected">' + selected_rel)
     return choose_units_form
 
+def get_fidelity_bond_data(taker):
+    with taker.dblock:
+        fbonds = taker.db.execute("SELECT * FROM fidelitybonds;").fetchall()
+
+    blocks = jm_single().bc_interface.get_current_block_height()
+    mediantime = jm_single().bc_interface.get_best_block_median_time()
+    interest_rate = get_interest_rate()
+
+    bond_utxo_set = set()
+    fidelity_bond_data = []
+    bond_outpoint_conf_times = []
+    fidelity_bond_values = []
+    for fb in fbonds:
+        try:
+            parsed_bond = FidelityBondProof.parse_and_verify_proof_msg(fb["counterparty"],
+                fb["takernick"], fb["proof"])
+        except ValueError:
+            continue
+        bond_utxo_data = FidelityBondMixin.get_validated_timelocked_fidelity_bond_utxo(
+            parsed_bond.utxo, parsed_bond.utxo_pub, parsed_bond.locktime, parsed_bond.cert_expiry,
+            blocks)
+        if bond_utxo_data == None:
+            continue
+        #check for duplicated utxos i.e. two or more makers using the same UTXO
+        # which is obviously not allowed, a fidelity bond must only be usable by one maker nick
+        utxo_str = parsed_bond.utxo[0] + b":" + str(parsed_bond.utxo[1]).encode("ascii")
+        if utxo_str in bond_utxo_set:
+            continue
+        bond_utxo_set.add(utxo_str)
+
+        fidelity_bond_data.append((parsed_bond, bond_utxo_data))
+        conf_time = jm_single().bc_interface.get_block_time(
+            jm_single().bc_interface.get_block_hash(
+                blocks - bond_utxo_data["confirms"] + 1
+            )
+        )
+        bond_outpoint_conf_times.append(conf_time)
+
+        bond_value = FidelityBondMixin.calculate_timelocked_fidelity_bond_value(
+            bond_utxo_data["value"],
+            conf_time,
+            parsed_bond.locktime,
+            mediantime,
+            interest_rate)
+        fidelity_bond_values.append(bond_value)
+    return (fidelity_bond_data, fidelity_bond_values, bond_outpoint_conf_times)
+
 class OrderbookPageRequestHeader(http.server.SimpleHTTPRequestHandler):
     def __init__(self, request, client_address, base_server):
         self.taker = base_server.taker
@@ -137,15 +204,21 @@ class OrderbookPageRequestHeader(http.server.SimpleHTTPRequestHandler):
                 directory=os.path.dirname(os.path.realpath(__file__)))
 
     def create_orderbook_obj(self):
-        try:
-            self.taker.dblock.acquire(True)
+        with self.taker.dblock:
             rows = self.taker.db.execute('SELECT * FROM orderbook;').fetchall()
-        finally:
-            self.taker.dblock.release()
-        if not rows:
+            fbonds = self.taker.db.execute("SELECT * FROM fidelitybonds;").fetchall()
+        if not rows or not fbonds:
             return []
 
-        result = []
+        if jm_single().bc_interface != None:
+            (fidelity_bond_data, fidelity_bond_values, bond_outpoint_conf_times) =\
+                get_fidelity_bond_data(self.taker)
+            fidelity_bond_values_dict = dict([(bond_data["counterparty"], bond_value)
+                for (bond_data, _), bond_value in zip(fidelity_bond_data, fidelity_bond_values)])
+        else:
+            fidelity_bond_values_dict = {}
+
+        offers = []
         for row in rows:
             o = dict(row)
             if 'cjfee' in o:
@@ -154,8 +227,19 @@ class OrderbookPageRequestHeader(http.server.SimpleHTTPRequestHandler):
                     o['cjfee'] = int(o['cjfee'])
                 else:
                     o['cjfee'] = str(Decimal(o['cjfee']))
-            result.append(o)
-        return result
+            o["fidelity_bond_value"] = fidelity_bond_values_dict.get(o["counterparty"], 0)
+            offers.append(o)
+
+        BIN_KEYS = ["txid", "utxopubkey"]
+        fidelitybonds = []
+        for fbond in fbonds:
+            o = dict(fbond)
+            for k in BIN_KEYS:
+                o[k] = bintohex(o[k])
+            o["fidelity_bond_value"] = fidelity_bond_values_dict.get(o["counterparty"], 0)
+            fidelitybonds.append(o)
+
+        return {"offers": offers, "fidelitybonds": fidelitybonds}
 
     def create_depth_chart(self, cj_amount, args=None):
         if 'matplotlib' not in sys.modules:
@@ -232,6 +316,166 @@ class OrderbookPageRequestHeader(http.server.SimpleHTTPRequestHandler):
         return get_graph_html(fig) + ("<br/><a href='?scale=log'>log scale</a>" if
                                       bins == 30 else "<br/><a href='?'>linear</a>")
 
+    def create_fidelity_bond_table(self, btc_unit):
+        if jm_single().bc_interface == None:
+            with self.taker.dblock:
+                fbonds = self.taker.db.execute("SELECT * FROM fidelitybonds;").fetchall()
+            fidelity_bond_data = []
+            for fb in fbonds:
+                try:
+                    proof = FidelityBondProof.parse_and_verify_proof_msg(
+                        fb["counterparty"],
+                        fb["takernick"],
+                        fb["proof"])
+                except ValueError:
+                    proof = None
+                fidelity_bond_data.append((proof, None))
+            fidelity_bond_values = [-1]*len(fidelity_bond_data) #-1 means no data
+            bond_outpoint_conf_times = [-1]*len(fidelity_bond_data)
+            total_btc_committed_str = "unknown"
+        else:
+            (fidelity_bond_data, fidelity_bond_values, bond_outpoint_conf_times) =\
+                get_fidelity_bond_data(self.taker)
+            total_btc_committed_str = satoshi_to_unit(
+                sum([utxo_data["value"] for _, utxo_data in fidelity_bond_data]),
+                None, btc_unit, 0)
+
+        RETARGET_INTERVAL = 2016
+        elem = lambda e: "<td>" + e + "</td>"
+        bondtable = ""
+        for (bond_data, utxo_data), bond_value, conf_time in zip(
+                fidelity_bond_data, fidelity_bond_values, bond_outpoint_conf_times):
+
+            if bond_value == -1 or conf_time == -1 or utxo_data == None:
+                bond_value_str = "No data"
+                conf_time_str = "No data"
+                utxo_value_str = "No data"
+            else:
+                bond_value_str = satoshi_to_unit_power(bond_value, 2*unit_to_power[btc_unit])
+                conf_time_str = str(datetime.utcfromtimestamp(conf_time))
+                utxo_value_str = satoshi_to_unit(utxo_data["value"], None, btc_unit, 0)
+            bondtable += ("<tr>"
+                + elem(bond_data.maker_nick)
+                + elem(bintohex(bond_data.utxo[0]) + ":" + str(bond_data.utxo[1]))
+                + elem(bond_value_str)
+                + elem(datetime.utcfromtimestamp(bond_data.locktime).strftime("%Y-%m-%d"))
+                + elem(utxo_value_str)
+                + elem(conf_time_str)
+                + elem(str(bond_data.cert_expiry*RETARGET_INTERVAL))
+                + elem(bintohex(btc.mk_freeze_script(bond_data.utxo_pub,
+                    bond_data.locktime)))
+                + "</tr>"
+            )
+
+        heading2 = (str(len(fidelity_bond_data)) + " fidelity bonds found with "
+            + total_btc_committed_str + " " + btc_unit
+            + " total locked up")
+        choose_units_form = (
+            '<form method="get" action="">' +
+            '<select name="btcunit" onchange="this.form.submit();">' +
+            ''.join(('<option>' + u + ' </option>' for u in sorted_units)) +
+            '</select></form>')
+        choose_units_form = choose_units_form.replace(
+                '<option>' + btc_unit,
+                '<option selected="selected">' + btc_unit)
+
+        decodescript_tip = ("<br/>Tip: try running the RPC <code>decodescript "
+            + "&lt;redeemscript&gt;</code> as proof that the fidelity bond address matches the "
+            + "locktime.<br/>Also run <code>gettxout &lt;utxo_txid&gt; &lt;utxo_vout&gt;</code> "
+            + "as proof that the fidelity bond UTXO is real.")
+
+        return (heading2,
+            choose_units_form + create_bonds_table_heading(btc_unit) + bondtable + "</table>"
+            + decodescript_tip)
+
+    def create_sybil_resistance_page(self, btc_unit):
+        if jm_single().bc_interface == None:
+            return "", "Calculations unavailable, requires configured bitcoin node."
+
+        (fidelity_bond_data, fidelity_bond_values, bond_outpoint_conf_times) =\
+            get_fidelity_bond_data(self.taker)
+
+        choose_units_form = (
+            '<form method="get" action="">' +
+            '<select name="btcunit" onchange="this.form.submit();">' +
+            ''.join(('<option>' + u + ' </option>' for u in sorted_units)) +
+            '</select></form>')
+        choose_units_form = choose_units_form.replace(
+                '<option>' + btc_unit,
+                '<option selected="selected">' + btc_unit)
+        mainbody = choose_units_form
+
+        honest_weight = sum(fidelity_bond_values)
+        mainbody += ("Assuming the makers in the offerbook right now are not sybil attackers, "
+            + "how much would a sybil attacker starting now have to sacrifice to succeed in their"
+            + " attack with 95% probability. Honest weight="
+            + satoshi_to_unit_power(honest_weight, 2*unit_to_power[btc_unit]) + " " + btc_unit
+            + "&#xb2;<br/>Also assumes that takers are not price-sensitive and that their max "
+            + "coinjoin fee is configured high enough that they dont exclude any makers.")
+        heading2 = "Sybil attacks from external enemies."
+
+        mainbody += ('<table class="tftable" border="1"><tr>'
+            + '<th>Maker count</th>'
+            + '<th>6month locked coins / ' + btc_unit + '</th>'
+            + '<th>1y locked coins / ' + btc_unit + '</th>'
+            + '<th>2y locked coins / ' + btc_unit + '</th>'
+            + '<th>5y locked coins / ' + btc_unit + '</th>'
+            + '<th>10y locked coins / ' + btc_unit + '</th>'
+            + '<th>Required burned coins / ' + btc_unit + '</th>'
+            + '</tr>'
+        )
+
+        timelocks = [0.5, 1.0, 2.0, 5.0, 10.0, None]
+        interest_rate = get_interest_rate()
+        for makercount, unit_success_sybil_weight in sybil.successful_attack_95pc_sybil_weight.items():
+            success_sybil_weight = unit_success_sybil_weight * honest_weight
+            row = "<tr><td>" + str(makercount) + "</td>"
+            for timelock in timelocks:
+                if timelock != None:
+                    coins_per_sybil = sybil.weight_to_locked_coins(success_sybil_weight,
+                        interest_rate, timelock)
+                else:
+                    coins_per_sybil = sybil.weight_to_burned_coins(success_sybil_weight)
+                row += ("<td>" + satoshi_to_unit(coins_per_sybil*makercount, None, btc_unit, 0)
+                    + "</td>")
+            row += "</tr>"
+            mainbody += row
+        mainbody += "</table>"
+
+        mainbody += ("<h2>Sybil attacks from enemies within</h2>Assume a sybil attack is ongoing"
+            + " right now and that the counterparties with the most valuable fidelity bonds are "
+            + " actually controlled by the same entity. Then, what is the probability of a "
+            + " successful sybil attack for a given makercount, and what is the fidelity bond "
+            + " value being foregone by not putting all bitcoins into just one maker.")
+        mainbody += ('<table class="tftable" border="1"><tr>'
+            + '<th>Maker count</th>'
+            + '<th>Success probability</th>'
+            + '<th>Foregone value / ' + btc_unit + '&#xb2;</th>'
+            + '</tr>'
+        )
+
+        #limited because calculation is slow, so this avoids server being too slow to respond
+        MAX_MAKER_COUNT_INTERNAL = 10
+        weights = sorted(fidelity_bond_values)[::-1]
+        for makercount in range(1, MAX_MAKER_COUNT_INTERNAL+1):
+            makercount_str = (str(makercount) + " - " + str(MAX_MAKER_COUNT_INTERNAL)
+                if makercount == len(fidelity_bond_data) and len(fidelity_bond_data) !=
+                MAX_MAKER_COUNT_INTERNAL else str(makercount))
+            success_prob = sybil.calculate_top_makers_sybil_attack_success_probability(weights,
+                makercount)
+            total_sybil_weight = sum(weights[:makercount])
+            sacrificed_values = [sybil.weight_to_burned_coins(w) for w in weights[:makercount]]
+            foregone_value = (sybil.coins_burned_to_weight(sum(sacrificed_values))
+                - total_sybil_weight)
+            mainbody += ("<tr><td>" + makercount_str + "</td><td>" + str(round(success_prob*100.0, 5))
+                + "%</td><td>" + satoshi_to_unit_power(foregone_value, 2*unit_to_power[btc_unit])
+                + "</td></tr>")
+            if makercount == len(weights):
+                break
+        mainbody += "</table>"
+
+        return heading2, mainbody
+
     def create_orderbook_table(self, btc_unit, rel_unit):
         result = ''
         try:
@@ -241,14 +485,59 @@ class OrderbookPageRequestHeader(http.server.SimpleHTTPRequestHandler):
             self.taker.dblock.release()
         if not rows:
             return 0, result
-        #print("len rows before filter: " + str(len(rows)))
         rows = [o for o in rows if o["ordertype"] in filtered_offername_list]
 
+        if jm_single().bc_interface == None:
+            for row in rows:
+                row["bondvalue"] = "No data"
+        else:
+            blocks = jm_single().bc_interface.get_current_block_height()
+            mediantime = jm_single().bc_interface.get_best_block_median_time()
+            interest_rate = get_interest_rate()
+            for row in rows:
+                with self.taker.dblock:
+                    fbond_data = self.taker.db.execute(
+                        "SELECT * FROM fidelitybonds WHERE counterparty=?;", (row["counterparty"],)
+                    ).fetchall()
+                if len(fbond_data) == 0:
+                    row["bondvalue"] = "0"
+                    continue
+                else:
+                    try:
+                        parsed_bond = FidelityBondProof.parse_and_verify_proof_msg(
+                            fbond_data[0]["counterparty"],
+                            fbond_data[0]["takernick"],
+                            fbond_data[0]["proof"]
+                        )
+                    except ValueError:
+                        row["bondvalue"] = "0"
+                        continue
+                    utxo_data = FidelityBondMixin.get_validated_timelocked_fidelity_bond_utxo(
+                        parsed_bond.utxo, parsed_bond.utxo_pub, parsed_bond.locktime,
+                        parsed_bond.cert_expiry, blocks)
+                    if utxo_data == None:
+                        row["bondvalue"] = "0"
+                        continue
+                    bond_value = FidelityBondMixin.calculate_timelocked_fidelity_bond_value(
+                        utxo_data["value"],
+                        jm_single().bc_interface.get_block_time(
+                            jm_single().bc_interface.get_block_hash(
+                                blocks - utxo_data["confirms"] + 1
+                            )
+                        ),
+                        parsed_bond.locktime,
+                        mediantime,
+                        interest_rate)
+                    row["bondvalue"] = satoshi_to_unit_power(bond_value, 2*unit_to_power[btc_unit])
+
         order_keys_display = (('ordertype', ordertype_display),
-                              ('counterparty', do_nothing), ('oid', order_str),
-                              ('cjfee', cjfee_display), ('txfee', satoshi_to_unit),
+                              ('counterparty', do_nothing),
+                              ('oid', order_str),
+                              ('cjfee', cjfee_display),
+                              ('txfee', satoshi_to_unit),
                               ('minsize', satoshi_to_unit),
-                              ('maxsize', satoshi_to_unit))
+                              ('maxsize', satoshi_to_unit),
+                              ('bondvalue', do_nothing))
 
         # somewhat complex sorting to sort by cjfee but with swabsoffers on top
 
@@ -278,16 +567,15 @@ class OrderbookPageRequestHeader(http.server.SimpleHTTPRequestHandler):
 
     def do_GET(self):
         # http.server.SimpleHTTPRequestHandler.do_GET(self)
-        # print 'httpd received ' + self.path + ' request'
+        # print('httpd received ' + self.path + ' request')
         self.path, query = self.path.split('?', 1) if '?' in self.path else (
             self.path, '')
         args = parse_qs(query)
-        pages = ['/', '/ordersize', '/depth', '/orderbook.json']
+        pages = ['/', '/fidelitybonds', '/ordersize', '/depth', '/sybilresistance',
+            '/orderbook.json']
         static_files = {'/vendor/sorttable.js', '/vendor/bootstrap.min.css', '/vendor/jquery-3.5.1.slim.min.js'}
-        if self.path in static_files:
+        if self.path in static_files or self.path not in pages:
             return super().do_GET()
-        elif self.path not in pages:
-            return
         fd = open(os.path.join(os.path.dirname(os.path.realpath(__file__)),
             'orderbook.html'), 'r')
         orderbook_fmt = fd.read()
@@ -308,7 +596,7 @@ class OrderbookPageRequestHeader(http.server.SimpleHTTPRequestHandler):
             ordercount, ordertable = self.create_orderbook_table(
                     btc_unit, rel_unit)
             choose_units_form = create_choose_units_form(btc_unit, rel_unit)
-            table_heading = create_table_heading(btc_unit, rel_unit)
+            table_heading = create_offerbook_table_heading(btc_unit, rel_unit)
             replacements = {
                 'PAGETITLE': 'JoinMarket Browser Interface',
                 'MAINHEADING': 'JoinMarket Orderbook',
@@ -319,6 +607,18 @@ class OrderbookPageRequestHeader(http.server.SimpleHTTPRequestHandler):
                     rotateObform + refresh_orderbook_form + choose_units_form +
                     table_heading + ordertable + '</table>\n')
             }
+        elif self.path == '/fidelitybonds':
+            btc_unit = args['btcunit'][0] if 'btcunit' in args else sorted_units[0]
+            if btc_unit not in sorted_units:
+                btc_unit = sorted_units[0]
+            heading2, mainbody = self.create_fidelity_bond_table(btc_unit)
+
+            replacements = {
+                'PAGETITLE': 'JoinMarket Browser Interface',
+                'MAINHEADING': 'Fidelity Bonds',
+                'SECONDHEADING': heading2,
+                'MAINBODY': mainbody
+            }
         elif self.path == '/ordersize':
             replacements = {
                 'PAGETITLE': 'JoinMarket Browser Interface',
@@ -340,6 +640,17 @@ class OrderbookPageRequestHeader(http.server.SimpleHTTPRequestHandler):
                 'SECONDHEADING': 'Orderbook Depth' + alert_msg,
                 'MAINBODY': '<br />'.join(mainbody)
             }
+        elif self.path == '/sybilresistance':
+            btc_unit = args['btcunit'][0] if 'btcunit' in args else sorted_units[0]
+            if btc_unit not in sorted_units:
+                btc_unit = sorted_units[0]
+            heading2, mainbody = self.create_sybil_resistance_page(btc_unit)
+            replacements = {
+                'PAGETITLE': 'JoinMarket Browser Interface',
+                'MAINHEADING': 'Resistance to Sybil Attacks from Fidelity Bonds',
+                'SECONDHEADING': heading2,
+                'MAINBODY': mainbody
+            }
         elif self.path == '/orderbook.json':
             replacements = {}
             orderbook_fmt = json.dumps(self.create_orderbook_obj())
@@ -437,6 +748,7 @@ class ObIRCMessageChannel(IRCMessageChannel):
             _chunks = command.split(" ")
             try:
                 self.check_for_orders(nick, _chunks)
+                self.check_for_fidelity_bond(nick, _chunks)
             except:
                 pass
 
diff --git a/scripts/obwatch/orderbook.html b/scripts/obwatch/orderbook.html
index 04f2f3c..45ad3a3 100644
--- a/scripts/obwatch/orderbook.html
+++ b/scripts/obwatch/orderbook.html
@@ -84,8 +84,10 @@
 	        <div id="navbar" class="collapse navbar-collapse">
 	          <ul class="nav navbar-nav">
 	            <li class="active"><a href=".">Orders</a></li>
+                <li><a href="fidelitybonds">Fidelity Bonds</a></li>
 	            <li><a href="ordersize">Size Distribution</a></li>
 	            <li><a href="depth">Depth</a></li>
+                <li><a href="sybilresistance">Sybil resistance</a></li>
 	            <li><a href="orderbook.json">Export orders</a></li>
 	            <li><a target="_blank" href="https://github.com/JoinMarket-Org/joinmarket-clientserver/releases">New segwit version</a></li>
 	          </ul>
diff --git a/scripts/obwatch/sybil_attack_calculations.py b/scripts/obwatch/sybil_attack_calculations.py
new file mode 100755
index 0000000..27255c8
--- /dev/null
+++ b/scripts/obwatch/sybil_attack_calculations.py
@@ -0,0 +1,81 @@
+
+##this file calculates the success probability of a sybil attack on the
+# orderbook with fidelity bonds used in joinmarket
+# see https://gist.github.com/chris-belcher/87ebbcbb639686057a389acb9ab3e25b
+
+
+#precomputed
+#what sybil weight is required per-maker to sybil attack joinmarket with 95% success rate
+#this is for when the honest weight (i.e. value of all fidelity bonds added up) equals 1
+#however it is linear, so to calculate for another honest_weight just multiply
+#see
+#https://gist.github.com/chris-belcher/87ebbcbb639686057a389acb9ab3e25b#appendix-1---fit-to-unit-honest-weight-sybil-attack
+successful_attack_95pc_sybil_weight = {
+    1: 19.2125,
+    2: 28.829523311823312,
+    3: 35.37299702466422,
+    4: 40.27618399827166,
+    5: 44.19631358837695,
+    6: 47.46160578701477,
+    7: 50.25944623742167,
+    8: 52.706868994753286,
+    9: 54.881852860047836,
+    10: 56.8389576639515,
+    11: 58.61784778500215,
+    12: 60.248261563672784,
+    13: 61.75306801,
+    14: 62.97189476,
+    15: 64.28155594,
+    16: 65.21832112385313,
+    17: 66.29765063354174,
+    18: 67.315269563541,
+    19: 68.27785449480159,
+    20: 69.19105386203657,
+    21: 70.05968878944397,
+    22: 70.88790716279642,
+    23: 71.67930342495613,
+    24: 72.43701285697972,
+    25: 73.16378660022
+}
+
+def descend_probability_tree(weights, remaining_descents, branch_probability):
+    if remaining_descents == 0:
+        return branch_probability
+    else:
+        total_weight = sum(weights)
+        result = 0
+        for i, w in enumerate(weights):
+            #honest makers are at index 0
+            if i == 0:
+                #an honest maker being chosen means the sybil attack failed
+                #so this branch contributes zero to the attack success prob
+                continue
+            if w == 0:
+                continue
+            weight_cache = weights[i]
+            weights[i] = 0
+            result += descend_probability_tree(weights,
+                remaining_descents-1, branch_probability*w/total_weight)
+            weights[i] = weight_cache
+        return result
+
+def calculate_top_makers_sybil_attack_success_probability(weights, taker_peer_count):
+    honest_weight = sum(weights[taker_peer_count:])
+    weights = [honest_weight] + weights[:taker_peer_count]
+    return descend_probability_tree(weights, taker_peer_count, 1.0)
+
+
+def weight_to_burned_coins(w):
+    #calculates how many coins need to be burned to produce a certain bond
+    return w**0.5
+
+def weight_to_locked_coins(w, r, locktime_months):
+    #calculates how many coins need to be locked to produce a certain bond
+    return w**0.5 / r / locktime_months * 12
+
+def coins_locked_to_weight(c, r, locktime_months):
+    return (c*r*locktime_months/12.0)**2
+
+def coins_burned_to_weight(c):
+    return c*c
+