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Reversing comments on pad and unpad.
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@futurechimp
futurechimp committed Jun 17, 2019
1 parent e5de1f3 commit d314122
Showing 1 changed file with 50 additions and 50 deletions.
100 changes: 50 additions & 50 deletions sphinxmix/SphinxClient.py
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Expand Up @@ -4,16 +4,16 @@
# Copyright 2016 George Danezis (UCL InfoSec Group)
#
# This file is part of Sphinx.
#
#
# Sphinx is free software: you can redistribute it and/or modify
# it under the terms of version 3 of the GNU Lesser General Public
# License as published by the Free Software Foundation.
#
#
# Sphinx is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
#
# You should have received a copy of the GNU Lesser General Public
# License along with Sphinx. If not, see
# <http://www.gnu.org/licenses/>.
Expand Down Expand Up @@ -53,29 +53,29 @@


def pad_body(msgtotalsize, body):
""" Unpad the Sphinx message body."""
""" Pad a Sphinx message body. """
body = body + b"\x7f"
body = body + (b"\xff" * (msgtotalsize - len(body)))

if (msgtotalsize - len(body)) < 0:
raise SphinxException("Insufficient space for body")
raise SphinxException("Insufficient space for body")

return body

def unpad_body(body):
""" Pad a Sphinx message body. """
""" Unpad the Sphinx message body."""
body = bytes(body)
l = len(body) - 1
x_marker = bytes(b"\x7f")[0]
f_marker = bytes(b"\xff")[0]
while body[l] == f_marker and l > 0:
l -= 1

if body[l] == x_marker:
ret = body[:l]
else:
ret = b''

return ret

# Prefix-free encoding/decoding of node names and destinations
Expand Down Expand Up @@ -109,10 +109,10 @@ def rand_subset(lst, nu):


def create_header(params, nodelist, keys, dest, assoc=None):
""" Internal function, creating a Sphinx header."""
""" Internal function, creating a Sphinx header."""

node_meta = [pack("b", len(n)) + n for n in nodelist]

if params.assoc_len > 0:
assoc = assoc
else:
Expand All @@ -125,18 +125,18 @@ def create_header(params, nodelist, keys, dest, assoc=None):
p = params
nu = len(nodelist)
max_len = p.max_len

group = p.group
x = group.gensecret()

blind_factors = [ x ]
asbtuples = []

from binascii import hexlify

for k in keys:
alpha = group.expon_base(blind_factors)

s = group.expon(k, blind_factors)
aes_s = p.get_aes_key(s)

Expand All @@ -159,20 +159,20 @@ def create_header(params, nodelist, keys, dest, assoc=None):
phi = phi[min_len:]

min_len -= len(node_meta[i]) + p.k


assert len(phi) == sum(map(len, node_meta[1:])) + (nu-1)*p.k

# Compute the (beta, gamma) tuples
# The os.urandom used to be a string of 0x00 bytes, but that's wrong

final_routing = pack("b", len(dest)) + dest

len_meta = sum(map(len, node_meta[1:]))
random_pad_len = (max_len - 32) - len_meta - (nu-1)*p.k - len(final_routing)

if random_pad_len < 0:
raise SphinxException("Insufficient space routing info")
raise SphinxException("Insufficient space routing info")

beta = final_routing + urandom(random_pad_len)
beta = p.xor_rho(p.hrho(asbtuples[nu-1].aes), beta) + phi
Expand All @@ -184,18 +184,18 @@ def create_header(params, nodelist, keys, dest, assoc=None):
node_id = node_meta[i+1]

plain_beta_len = (max_len - 32) - p.k - len(node_id)

plain = node_id + gamma + beta[:plain_beta_len]
beta = p.xor_rho(p.hrho(asbtuples[i].aes), plain)
gamma = p.mu(p.hmu(asbtuples[i].aes), assoc[i] + beta)

beta = p.xor_rho(p.hrho(asbtuples[i].aes), plain)
gamma = p.mu(p.hmu(asbtuples[i].aes), assoc[i] + beta)

return (asbtuples[0].alpha, beta, gamma), \
[x.aes for x in asbtuples]


def create_forward_message(params, nodelist, keys, dest, msg, assoc=None):
"""Creates a forward Sphix message, ready to be processed by a first mix.
"""Creates a forward Sphix message, ready to be processed by a first mix.
It takes as parameters a node list of mix information, that will be provided to each mix, forming the path of the message;
a list of public keys of all intermediate mixes; a destination and a message; and optinally an array of associated data (byte arrays)."""
Expand Down Expand Up @@ -225,12 +225,12 @@ def create_forward_message(params, nodelist, keys, dest, msg, assoc=None):

def create_surb(params, nodelist, keys, dest, assoc=None):
"""Creates a Sphinx single use reply block (SURB) using a set of parameters;
a sequence of mix identifiers; a pki mapping names of mixes to keys; and a final
a sequence of mix identifiers; a pki mapping names of mixes to keys; and a final
destination. An array of associated data, for each mix on the path, may optionally
be passed in.
Returns:
- A triplet (surbid, surbkeytuple, nymtuple). Where the surbid can be
- A triplet (surbid, surbkeytuple, nymtuple). Where the surbid can be
used as an index to store the secrets surbkeytuple; nymtuple is the actual
SURB that needs to be sent to the receiver.
Expand All @@ -249,7 +249,7 @@ def create_surb(params, nodelist, keys, dest, assoc=None):
return xid, keytuple, (nodelist[0], header, ktilde)

def package_surb(params, nymtuple, message):
"""Packages a message to be sent with a SURB. The message has to be bytes,
"""Packages a message to be sent with a SURB. The message has to be bytes,
and the nymtuple is the structure returned by the create_surb call.
Returns a header and a body to pass to the first mix.
Expand All @@ -264,21 +264,21 @@ def package_surb(params, nymtuple, message):

def receive_forward(params, mac_key, delta):
""" Decodes the body of a forward message, and checks its MAC tag."""

if delta[:params.k] != params.mu(mac_key, delta[params.k:]):
raise SphinxException("Modified Body")

delta = unpad_body(delta[params.k:])
return decode(delta)

def receive_surb(params, keytuple, delta):
"""Processes a SURB body to extract the reply. The keytuple was provided at the time of
def receive_surb(params, keytuple, delta):
"""Processes a SURB body to extract the reply. The keytuple was provided at the time of
SURB creation, and can be indexed by the SURB id, which is also returned to the receiving user.
Returns the decoded message.
"""
p = params

ktilde = keytuple.pop(0)
nu = len(keytuple)
for i in range(nu-1, -1, -1):
Expand All @@ -289,7 +289,7 @@ def receive_surb(params, keytuple, delta):
msg = unpad_body(delta[p.k:])
else:
raise SphinxException("Modified SURB Body")

return msg

def pack_message(params, m):
Expand All @@ -307,7 +307,7 @@ def test_timing(rep=100, payload_size=1024 * 10):
r = 5
params = SphinxParams(body_len=payload_size)
pki = {}

pkiPriv = {}
pkiPub = {}

Expand All @@ -323,7 +323,7 @@ def test_timing(rep=100, payload_size=1024 * 10):
nodes_routing = list(map(Nenc, use_nodes))
node_keys = [pkiPub[n].y for n in use_nodes]
print()

import time
t0 = time.time()
for _ in range(rep):
Expand Down Expand Up @@ -352,7 +352,7 @@ def test_minimal():
params = SphinxParams()

# The minimal PKI involves names of nodes and keys

pkiPriv = {}
pkiPub = {}

Expand Down Expand Up @@ -398,7 +398,7 @@ def test_minimal():
# print("Type: %s" % typex)
if routing[0] == Relay_flag:
addr = routing[1]
x = pkiPriv[addr].x
x = pkiPriv[addr].x
elif routing[0] == Dest_flag:
assert len(routing) == 1
# assert delta[:16] == b"\x00" * params.k
Expand All @@ -414,7 +414,7 @@ def test_minimal():

# Test the nym creation
surbid, surbkeytuple, nymtuple = create_surb(params, nodes_routing, node_keys, b"myself")

message = b"This is a reply"
header, delta = package_surb(params, nymtuple, message)

Expand All @@ -427,7 +427,7 @@ def test_minimal():

if routing[0] == Relay_flag:
flag, addr = routing
x = pkiPriv[addr].x
x = pkiPriv[addr].x
elif routing[0] == Surb_flag:
flag, dest, myid = routing
break
Expand All @@ -439,7 +439,7 @@ def test_assoc(rep=100, payload_size=1024 * 10):
r = 5
params = SphinxParams(body_len=payload_size, assoc_len=4)
pki = {}

pkiPriv = {}
pkiPub = {}

Expand All @@ -458,7 +458,7 @@ def test_assoc(rep=100, payload_size=1024 * 10):
print()

assoc = [b"XXXX"] * len(nodes_routing)

import time
t0 = time.time()
for _ in range(rep):
Expand All @@ -484,7 +484,7 @@ def test_assoc(rep=100, payload_size=1024 * 10):
def test_c25519(rep=100, payload_size=1024 * 10):
r = 5
from .SphinxParamsC25519 import Group_C25519

group = Group_C25519()
params = SphinxParams(group=group, body_len=payload_size, assoc_len=4)

Expand All @@ -494,7 +494,7 @@ def test_c25519(rep=100, payload_size=1024 * 10):


pki = {}

pkiPriv = {}
pkiPub = {}

Expand All @@ -513,7 +513,7 @@ def test_c25519(rep=100, payload_size=1024 * 10):
print()

assoc = [b"XXXX"] * len(nodes_routing)

import time
t0 = time.time()
for _ in range(rep):
Expand All @@ -537,7 +537,7 @@ def test_c25519(rep=100, payload_size=1024 * 10):
def test_c25519_hemi(rep=1, payload_size=1024):
r = 5
from .SphinxParamsC25519 import Group_C25519

group = Group_C25519()
params = SphinxParams(group=group, body_len=payload_size, assoc_len=4)

Expand All @@ -547,7 +547,7 @@ def test_c25519_hemi(rep=1, payload_size=1024):


pki = {}

pkiPriv = {}
pkiPub = {}

Expand All @@ -563,11 +563,11 @@ def test_c25519_hemi(rep=1, payload_size=1024):
use_nodes = rand_subset(pkiPub.keys(), r)
nodes_routing = list(map(Nenc, use_nodes))
node_keys = [pkiPub[n].y for n in use_nodes]

assoc = [b"XXXX"] * len(nodes_routing)

header, delta = create_forward_message(params, nodes_routing, node_keys, b"dest", b"this is a test", assoc)


from .SphinxNode import sphinx_process
from binascii import hexlify
Expand All @@ -584,7 +584,7 @@ def test_c25519_hemi(rep=1, payload_size=1024):

routing = PFdecode(params, B)
assert i == 4 or B == nodes_routing[i+1]

i += 1

if routing[0] == Relay_flag:
Expand All @@ -602,9 +602,9 @@ def test_c25519_hemi(rep=1, payload_size=1024):
print("Error")
assert False
break




if __name__ == "__main__":
test_timing()
test_timing()

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