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Patches to support sha256 based hmac and kexgex #356

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Patches to support sha256 based hmac and kexgex #356

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bd21af3
Add support for sha256 based hmac and kexgex
zamiam69 Jul 15, 2014
f4cfd19
Add support for sha256 based hmac and kexgex
zamiam69 Jul 15, 2014
f41cb94
Merge branch 'add_sha2_support' of github.com:zamiam69/paramiko into …
zamiam69 Jul 15, 2014
26b11d0
Fix transport test
zamiam69 Jul 15, 2014
47da193
Include sha2 changes in tests
zamiam69 Jul 16, 2014
b3b0f2d
Merge upstream branch 'master' into add_sha2_support
zamiam69 Nov 25, 2014
1b04ef0
Merge upstream and fix format string syntax
zamiam69 Oct 24, 2015
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13 changes: 9 additions & 4 deletions paramiko/kex_gex.py
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@
"""

import os
from hashlib import sha1
from hashlib import sha1, sha256

from paramiko import util
from paramiko.common import DEBUG
Expand All @@ -44,6 +44,7 @@ class KexGex (object):
min_bits = 1024
max_bits = 8192
preferred_bits = 2048
hash_algo = sha1

def __init__(self, transport):
self.transport = transport
Expand Down Expand Up @@ -87,7 +88,7 @@ def parse_next(self, ptype, m):
return self._parse_kexdh_gex_reply(m)
elif ptype == _MSG_KEXDH_GEX_REQUEST_OLD:
return self._parse_kexdh_gex_request_old(m)
raise SSHException('KexGex asked to handle packet type %d' % ptype)
raise SSHException('KexGex %s asked to handle packet type %d' % (self.name, ptype))

### internals...

Expand Down Expand Up @@ -204,7 +205,7 @@ def _parse_kexdh_gex_init(self, m):
hm.add_mpint(self.e)
hm.add_mpint(self.f)
hm.add_mpint(K)
H = sha1(hm.asbytes()).digest()
H = self.hash_algo(hm.asbytes()).digest()
self.transport._set_K_H(K, H)
# sign it
sig = self.transport.get_server_key().sign_ssh_data(H)
Expand Down Expand Up @@ -239,6 +240,10 @@ def _parse_kexdh_gex_reply(self, m):
hm.add_mpint(self.e)
hm.add_mpint(self.f)
hm.add_mpint(K)
self.transport._set_K_H(K, sha1(hm.asbytes()).digest())
self.transport._set_K_H(K, self.hash_algo(hm.asbytes()).digest())
self.transport._verify_key(host_key, sig)
self.transport._activate_outbound()

class KexGexSHA256(KexGex):
name = 'diffie-hellman-group-exchange-sha256'
hash_algo = sha256
27 changes: 18 additions & 9 deletions paramiko/transport.py
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,7 @@
import threading
import time
import weakref
from hashlib import md5, sha1
from hashlib import md5, sha1, sha256

import paramiko
from paramiko import util
Expand All @@ -47,7 +47,7 @@
DEFAULT_WINDOW_SIZE, DEFAULT_MAX_PACKET_SIZE
from paramiko.compress import ZlibCompressor, ZlibDecompressor
from paramiko.dsskey import DSSKey
from paramiko.kex_gex import KexGex
from paramiko.kex_gex import KexGex, KexGexSHA256
from paramiko.kex_group1 import KexGroup1
from paramiko.kex_group14 import KexGroup14
from paramiko.kex_gss import KexGSSGex, KexGSSGroup1, KexGSSGroup14, NullHostKey
Expand Down Expand Up @@ -96,9 +96,13 @@ class Transport (threading.Thread, ClosingContextManager):

_preferred_ciphers = ('aes128-ctr', 'aes256-ctr', 'aes128-cbc', 'blowfish-cbc',
'aes256-cbc', '3des-cbc', 'arcfour128', 'arcfour256')
_preferred_macs = ('hmac-sha1', 'hmac-md5', 'hmac-sha1-96', 'hmac-md5-96')
_preferred_macs = ('hmac-sha1', 'hmac-md5', 'hmac-sha1-96', 'hmac-md5-96',
'hmac-sha2-256')
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Is this in order of preference? If it is then hmac-sha2-256 should be first.

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If it works anything like the OpenSSH implementation, then yes, they are in order of preference, so I would suggest putting it first.

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For reference, one of the tickets about auth key handling is #387 I added it as I think it might help give some insight into this problem.

_preferred_keys = ('ssh-rsa', 'ssh-dss', 'ecdsa-sha2-nistp256')
_preferred_kex = ( 'diffie-hellman-group14-sha1', 'diffie-hellman-group-exchange-sha1' , 'diffie-hellman-group1-sha1')
_preferred_kex = ('diffie-hellman-group-exchange-sha256',
'diffie-hellman-group14-sha1',
'diffie-hellman-group-exchange-sha1' ,
'diffie-hellman-group1-sha1')
_preferred_compression = ('none',)

_cipher_info = {
Expand All @@ -115,6 +119,7 @@ class Transport (threading.Thread, ClosingContextManager):
_mac_info = {
'hmac-sha1': {'class': sha1, 'size': 20},
'hmac-sha1-96': {'class': sha1, 'size': 12},
'hmac-sha2-256': {'class': sha256, 'size': 32},
'hmac-md5': {'class': md5, 'size': 16},
'hmac-md5-96': {'class': md5, 'size': 12},
}
Expand All @@ -129,6 +134,7 @@ class Transport (threading.Thread, ClosingContextManager):
'diffie-hellman-group1-sha1': KexGroup1,
'diffie-hellman-group14-sha1': KexGroup14,
'diffie-hellman-group-exchange-sha1': KexGex,
'diffie-hellman-group-exchange-sha256': KexGexSHA256,
'gss-group1-sha1-toWM5Slw5Ew8Mqkay+al2g==': KexGSSGroup1,
'gss-group14-sha1-toWM5Slw5Ew8Mqkay+al2g==': KexGSSGroup14,
'gss-gex-sha1-toWM5Slw5Ew8Mqkay+al2g==': KexGSSGex
Expand Down Expand Up @@ -1495,13 +1501,14 @@ def _compute_key(self, id, nbytes):
m.add_bytes(self.H)
m.add_byte(b(id))
m.add_bytes(self.session_id)
out = sofar = sha1(m.asbytes()).digest()
hash_algo = self._mac_info[self.local_mac]['class'] if self.local_mac else sha1
out = sofar = hash_algo(m.asbytes()).digest()
while len(out) < nbytes:
m = Message()
m.add_mpint(self.K)
m.add_bytes(self.H)
m.add_bytes(sofar)
digest = sha1(m.asbytes()).digest()
digest = hash_algo(m.asbytes()).digest()
out += digest
sofar += digest
return out[:nbytes]
Expand Down Expand Up @@ -1742,10 +1749,12 @@ def _send_kex_init(self):
self.clear_to_send_lock.release()
self.in_kex = True
if self.server_mode:
if (self._modulus_pack is None) and ('diffie-hellman-group-exchange-sha1' in self._preferred_kex):
mp_required_prefix = 'diffie-hellman-group-exchange-sha'
kex_mp = [k for k in self._preferred_kex if k.startswith(mp_required_prefix)]
if (self._modulus_pack is None) and (len(kex_mp) > 0):
# can't do group-exchange if we don't have a pack of potential primes
pkex = list(self.get_security_options().kex)
pkex.remove('diffie-hellman-group-exchange-sha1')
pkex = [k for k in self.get_security_options().kex
if not k.startswith(mp_required_prefix)]
self.get_security_options().kex = pkex
available_server_keys = list(filter(list(self.server_key_dict.keys()).__contains__,
self._preferred_keys))
Expand Down
119 changes: 118 additions & 1 deletion tests/test_kex.py
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,7 @@

import paramiko.util
from paramiko.kex_group1 import KexGroup1
from paramiko.kex_gex import KexGex
from paramiko.kex_gex import KexGex, KexGexSHA256
from paramiko import Message
from paramiko.common import byte_chr

Expand Down Expand Up @@ -252,3 +252,120 @@ def test_6_gex_server_with_old_client(self):
self.assertEqual(H, hexlify(transport._H).upper())
self.assertEqual(x, hexlify(transport._message.asbytes()).upper())
self.assertTrue(transport._activated)

def test_7_gex_sha256_client(self):
transport = FakeTransport()
transport.server_mode = False
kex = KexGexSHA256(transport)
kex.start_kex()
x = b'22000004000000080000002000'
self.assertEqual(x, hexlify(transport._message.asbytes()).upper())
self.assertEqual((paramiko.kex_gex._MSG_KEXDH_GEX_GROUP,), transport._expect)

msg = Message()
msg.add_mpint(FakeModulusPack.P)
msg.add_mpint(FakeModulusPack.G)
msg.rewind()
kex.parse_next(paramiko.kex_gex._MSG_KEXDH_GEX_GROUP, msg)
x = b'20000000807E2DDB1743F3487D6545F04F1C8476092FB912B013626AB5BCEB764257D88BBA64243B9F348DF7B41B8C814A995E00299913503456983FFB9178D3CD79EB6D55522418A8ABF65375872E55938AB99A84A0B5FC8A1ECC66A7C3766E7E0F80B7CE2C9225FC2DD683F4764244B72963BBB383F529DCF0C5D17740B8A2ADBE9208D4'
self.assertEqual(x, hexlify(transport._message.asbytes()).upper())
self.assertEqual((paramiko.kex_gex._MSG_KEXDH_GEX_REPLY,), transport._expect)

msg = Message()
msg.add_string('fake-host-key')
msg.add_mpint(69)
msg.add_string('fake-sig')
msg.rewind()
kex.parse_next(paramiko.kex_gex._MSG_KEXDH_GEX_REPLY, msg)
H = b'AD1A9365A67B4496F05594AD1BF656E3CDA0851289A4C1AFF549FEAE50896DF4'
self.assertEqual(self.K, transport._K)
self.assertEqual(H, hexlify(transport._H).upper())
self.assertEqual((b'fake-host-key', b'fake-sig'), transport._verify)
self.assertTrue(transport._activated)

def test_8_gex_sha256_old_client(self):
transport = FakeTransport()
transport.server_mode = False
kex = KexGexSHA256(transport)
kex.start_kex(_test_old_style=True)
x = b'1E00000800'
self.assertEqual(x, hexlify(transport._message.asbytes()).upper())
self.assertEqual((paramiko.kex_gex._MSG_KEXDH_GEX_GROUP,), transport._expect)

msg = Message()
msg.add_mpint(FakeModulusPack.P)
msg.add_mpint(FakeModulusPack.G)
msg.rewind()
kex.parse_next(paramiko.kex_gex._MSG_KEXDH_GEX_GROUP, msg)
x = b'20000000807E2DDB1743F3487D6545F04F1C8476092FB912B013626AB5BCEB764257D88BBA64243B9F348DF7B41B8C814A995E00299913503456983FFB9178D3CD79EB6D55522418A8ABF65375872E55938AB99A84A0B5FC8A1ECC66A7C3766E7E0F80B7CE2C9225FC2DD683F4764244B72963BBB383F529DCF0C5D17740B8A2ADBE9208D4'
self.assertEqual(x, hexlify(transport._message.asbytes()).upper())
self.assertEqual((paramiko.kex_gex._MSG_KEXDH_GEX_REPLY,), transport._expect)

msg = Message()
msg.add_string('fake-host-key')
msg.add_mpint(69)
msg.add_string('fake-sig')
msg.rewind()
kex.parse_next(paramiko.kex_gex._MSG_KEXDH_GEX_REPLY, msg)
H = b'518386608B15891AE5237DEE08DCADDE76A0BCEFCE7F6DB3AD66BC41D256DFE5'
self.assertEqual(self.K, transport._K)
self.assertEqual(H, hexlify(transport._H).upper())
self.assertEqual((b'fake-host-key', b'fake-sig'), transport._verify)
self.assertTrue(transport._activated)

def test_9_gex_sha256_server(self):
transport = FakeTransport()
transport.server_mode = True
kex = KexGexSHA256(transport)
kex.start_kex()
self.assertEqual((paramiko.kex_gex._MSG_KEXDH_GEX_REQUEST, paramiko.kex_gex._MSG_KEXDH_GEX_REQUEST_OLD), transport._expect)

msg = Message()
msg.add_int(1024)
msg.add_int(2048)
msg.add_int(4096)
msg.rewind()
kex.parse_next(paramiko.kex_gex._MSG_KEXDH_GEX_REQUEST, msg)
x = b'1F0000008100FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF0000000102'
self.assertEqual(x, hexlify(transport._message.asbytes()).upper())
self.assertEqual((paramiko.kex_gex._MSG_KEXDH_GEX_INIT,), transport._expect)

msg = Message()
msg.add_mpint(12345)
msg.rewind()
kex.parse_next(paramiko.kex_gex._MSG_KEXDH_GEX_INIT, msg)
K = 67592995013596137876033460028393339951879041140378510871612128162185209509220726296697886624612526735888348020498716482757677848959420073720160491114319163078862905400020959196386947926388406687288901564192071077389283980347784184487280885335302632305026248574716290537036069329724382811853044654824945750581
H = b'CCAC0497CF0ABA1DBF55E1A3995D17F4CC31824B0E8D95CDF8A06F169D050D80'
x = b'210000000866616B652D6B6579000000807E2DDB1743F3487D6545F04F1C8476092FB912B013626AB5BCEB764257D88BBA64243B9F348DF7B41B8C814A995E00299913503456983FFB9178D3CD79EB6D55522418A8ABF65375872E55938AB99A84A0B5FC8A1ECC66A7C3766E7E0F80B7CE2C9225FC2DD683F4764244B72963BBB383F529DCF0C5D17740B8A2ADBE9208D40000000866616B652D736967'
self.assertEqual(K, transport._K)
self.assertEqual(H, hexlify(transport._H).upper())
self.assertEqual(x, hexlify(transport._message.asbytes()).upper())
self.assertTrue(transport._activated)

def test_10_gex_sha256_server_with_old_client(self):
transport = FakeTransport()
transport.server_mode = True
kex = KexGexSHA256(transport)
kex.start_kex()
self.assertEqual((paramiko.kex_gex._MSG_KEXDH_GEX_REQUEST, paramiko.kex_gex._MSG_KEXDH_GEX_REQUEST_OLD), transport._expect)

msg = Message()
msg.add_int(2048)
msg.rewind()
kex.parse_next(paramiko.kex_gex._MSG_KEXDH_GEX_REQUEST_OLD, msg)
x = b'1F0000008100FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF0000000102'
self.assertEqual(x, hexlify(transport._message.asbytes()).upper())
self.assertEqual((paramiko.kex_gex._MSG_KEXDH_GEX_INIT,), transport._expect)

msg = Message()
msg.add_mpint(12345)
msg.rewind()
kex.parse_next(paramiko.kex_gex._MSG_KEXDH_GEX_INIT, msg)
K = 67592995013596137876033460028393339951879041140378510871612128162185209509220726296697886624612526735888348020498716482757677848959420073720160491114319163078862905400020959196386947926388406687288901564192071077389283980347784184487280885335302632305026248574716290537036069329724382811853044654824945750581
H = b'3DDD2AD840AD095E397BA4D0573972DC60F6461FD38A187CACA6615A5BC8ADBB'
x = b'210000000866616B652D6B6579000000807E2DDB1743F3487D6545F04F1C8476092FB912B013626AB5BCEB764257D88BBA64243B9F348DF7B41B8C814A995E00299913503456983FFB9178D3CD79EB6D55522418A8ABF65375872E55938AB99A84A0B5FC8A1ECC66A7C3766E7E0F80B7CE2C9225FC2DD683F4764244B72963BBB383F529DCF0C5D17740B8A2ADBE9208D40000000866616B652D736967'
self.assertEqual(K, transport._K)
self.assertEqual(H, hexlify(transport._H).upper())
self.assertEqual(x, hexlify(transport._message.asbytes()).upper())
self.assertTrue(transport._activated)

5 changes: 4 additions & 1 deletion tests/test_transport.py
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@
import time
import threading
import random
from hashlib import sha1
import unittest

from paramiko import Transport, SecurityOptions, ServerInterface, RSAKey, DSSKey, \
Expand Down Expand Up @@ -447,9 +448,11 @@ def force_compression(o):
bytes = self.tc.packetizer._Packetizer__sent_bytes
chan.send('x' * 1024)
bytes2 = self.tc.packetizer._Packetizer__sent_bytes
block_size = self.tc._cipher_info[self.tc.local_cipher]['block-size']
mac_size = self.tc._mac_info[self.tc.local_mac]['size']
# tests show this is actually compressed to *52 bytes*! including packet overhead! nice!! :)
self.assertTrue(bytes2 - bytes < 1024)
self.assertEqual(52, bytes2 - bytes)
self.assertEqual(16 + block_size + mac_size, bytes2 - bytes)

chan.close()
schan.close()
Expand Down