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Validate message signature encoding #1070

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Nov 29, 2021
Merged

Validate message signature encoding #1070

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27 changes: 21 additions & 6 deletions jmdaemon/jmdaemon/message_channel.py
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@
encrypted_commands, commitment_broadcast_list, offername_list,\
fidelity_bond_cmd_list
from jmbase.support import get_log
from jmbase import hextobin
from functools import wraps

log = get_log()
Expand Down Expand Up @@ -918,24 +919,38 @@ def on_privmsg(self, nick, message):
#Other ill formatted messages will be caught in the try block.
if len(message) < 2:
return

if message[0] != COMMAND_PREFIX:
log.debug('message not a cmd')
return
cmd_string = message[1:].split(' ')[0]
if cmd_string not in plaintext_commands + encrypted_commands:
log.debug('cmd not in cmd_list, line="' + message + '"')
return
badsigmsg = "Sig not properly appended to privmsg, ignoring"
#Verify nick ownership
sig = message[1:].split(' ')[-2:]
try:
pub, sig = message[1:].split(' ')[-2:]
except Exception:
log.debug(badsigmsg)
return
#reconstruct original message without cmd
rawmessage = ' '.join(message[1:].split(' ')[1:-2])
#sanity check that the sig was appended properly
if len(sig) != 2 or len(rawmessage) == 0:
log.debug("Sig not properly appended to privmsg, ignoring")
# can happen if not enough fields for command, (stuff), pub, sig:
if len(rawmessage) == 0:
log.debug(badsigmsg)
return
# Sanitising signature before attempting to verify:
# Note that the sig itself can be any garbage, because `ecdsa_verify`
# swallows any fail and returns False; but the pubkey is assumed
# to be hex-encoded, and the signature base64 encoded, so check early:
try:
dummypub = hextobin(pub)
dummysig = base64.b64decode(sig)
except Exception:
log.debug(badsigmsg)
return
self.daemon.request_signature_verify(
rawmessage + str(self.hostid), message, sig[1], sig[0], nick,
rawmessage + str(self.hostid), message, sig, pub, nick,
NICK_HASH_LENGTH, NICK_MAX_ENCODED, str(self.hostid))

def on_verified_privmsg(self, nick, message):
Expand Down
13 changes: 8 additions & 5 deletions jmdaemon/test/test_message_channel.py
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Original file line number Diff line number Diff line change
Expand Up @@ -17,8 +17,11 @@
import threading
import binascii
import jmbitcoin as bitcoin
from jmbase import bintohex
from dummy_mc import DummyMessageChannel

# note: completely invalid sig is fine, as long as it's encoded right:
dummy_sig_str = bintohex(b"\x02"*33) + " " + base64.b64encode(b"\x01"*72).decode()

jlog = get_log()

Expand Down Expand Up @@ -151,8 +154,8 @@ def test_setup_mc():
#Simulate order receipt on 2 of 3 msgchans from this nick;
#note that it will have its active chan set to mc "1" because that
#is the last it was seen on:
dmcs[0].on_privmsg(cp1, "!reloffer 0 4000 5000 100 0.2 abc def")
dmcs[1].on_privmsg(cp1, "!reloffer 0 4000 5000 100 0.2 abc def")
dmcs[0].on_privmsg(cp1, "!reloffer 0 4000 5000 100 0.2 " + dummy_sig_str)
dmcs[1].on_privmsg(cp1, "!reloffer 0 4000 5000 100 0.2 " + dummy_sig_str)
time.sleep(0.5)
#send back a response
mcc.privmsg(cp1, "fill", "0")
Expand Down Expand Up @@ -210,7 +213,7 @@ def test_setup_mc():
#first, pretend they all showed up on all 3 mcs:
for m in dmcs:
for cp in cps:
m.on_privmsg(cp, "!reloffer 0 400000 500000 100 0.002 abc def")
m.on_privmsg(cp, "!reloffer 0 400000 500000 100 0.002 " + dummy_sig_str)
#next, call main fill function
mcc.fill_orders(new_offers, 1000, "dummypubkey", "dummycommit")
#now send a dummy transaction to this same set.
Expand Down Expand Up @@ -242,7 +245,7 @@ def test_setup_mc():
#have the cps rearrive
for m in dmcs:
for cp in cps:
m.on_privmsg(cp, "!reloffer 0 4000 5000 100 0.2 abc def")
m.on_privmsg(cp, "!reloffer 0 4000 5000 100 0.2 " + dummy_sig_str)

#####################################################################
#next series of messages are to test various normal and abnormal
Expand All @@ -255,7 +258,7 @@ def test_setup_mc():
#invalid missing field
dmcs[0].on_pubmsg(cps[2], "!hp2")
#receive commitment via privmsg to trigger commitment_transferred
dmcs[0].on_privmsg(cps[2], "!hp2 deadbeef abc def")
dmcs[0].on_privmsg(cps[2], "!hp2 deadbeef " + dummy_sig_str)
#simulate receipt of order cancellation
#valid
dmcs[0].on_pubmsg(cps[2], "!cancel 2")
Expand Down