[project @ Arch-1:robey@lag.net--2003-public%secsh--dev--1.0--patch-107]

fix kex_gex
fix kex_gex (group-exchange key exchange) to, *cough*, work again, and also
layout kex_group1 a little more sanely.
This commit is contained in:
Robey Pointer 2004-11-07 02:31:48 +00:00
parent 5a1b5848ae
commit 2f3228dd88
2 changed files with 47 additions and 25 deletions

View File

@ -72,6 +72,10 @@ class KexGex (object):
return self._parse_kexdh_gex_reply(m)
raise SSHException('KexGex asked to handle packet type %d' % ptype)
### internals...
def _generate_x(self):
# generate an "x" (1 < x < (p-1)/2).
q = (self.p - 1) // 2
@ -82,7 +86,7 @@ class KexGex (object):
while not (qhbyte & 0x80):
qhbyte <<= 1
qmask >>= 1
while 1:
while True:
self.transport.randpool.stir()
x_bytes = self.transport.randpool.get_bytes(bytes)
x_bytes = chr(ord(x_bytes[0]) & qmask) + x_bytes[1:]
@ -152,8 +156,15 @@ class KexGex (object):
hm = Message()
hm.add(self.transport.remote_version, self.transport.local_version,
self.transport.remote_kex_init, self.transport.local_kex_init,
key, self.min_bits, self.preferred_bits, self.max_bits,
self.p, self.g, self.e, self.f, K)
key)
hm.add_int(self.min_bits)
hm.add_int(self.preferred_bits)
hm.add_int(self.max_bits)
hm.add_mpint(self.p)
hm.add_mpint(self.g)
hm.add_mpint(self.e)
hm.add_mpint(self.f)
hm.add_mpint(K)
H = SHA.new(str(hm)).digest()
self.transport._set_K_H(K, H)
# sign it
@ -178,8 +189,15 @@ class KexGex (object):
hm = Message()
hm.add(self.transport.local_version, self.transport.remote_version,
self.transport.local_kex_init, self.transport.remote_kex_init,
host_key, self.min_bits, self.preferred_bits, self.max_bits,
self.p, self.g, self.e, self.f, K)
host_key)
hm.add_int(self.min_bits)
hm.add_int(self.preferred_bits)
hm.add_int(self.max_bits)
hm.add_mpint(self.p)
hm.add_mpint(self.g)
hm.add_mpint(self.e)
hm.add_mpint(self.f)
hm.add_mpint(K)
self.transport._set_K_H(K, SHA.new(str(hm)).digest())
self.transport._verify_key(host_key, sig)
self.transport._activate_outbound()

View File

@ -44,23 +44,8 @@ class KexGroup1(object):
def __init__(self, transport):
self.transport = transport
def generate_x(self):
# generate an "x" (1 < x < q), where q is (p-1)/2.
# p is a 128-byte (1024-bit) number, where the first 64 bits are 1.
# therefore q can be approximated as a 2^1023. we drop the subset of
# potential x where the first 63 bits are 1, because some of those will be
# larger than q (but this is a tiny tiny subset of potential x).
while 1:
self.transport.randpool.stir()
x_bytes = self.transport.randpool.get_bytes(128)
x_bytes = chr(ord(x_bytes[0]) & 0x7f) + x_bytes[1:]
if (x_bytes[:8] != '\x7F\xFF\xFF\xFF\xFF\xFF\xFF\xFF') and \
(x_bytes[:8] != '\x00\x00\x00\x00\x00\x00\x00\x00'):
break
self.x = util.inflate_long(x_bytes)
def start_kex(self):
self.generate_x()
self._generate_x()
if self.transport.server_mode:
# compute f = g^x mod p, but don't send it yet
self.f = pow(G, self.x, P)
@ -76,12 +61,31 @@ class KexGroup1(object):
def parse_next(self, ptype, m):
if self.transport.server_mode and (ptype == _MSG_KEXDH_INIT):
return self.parse_kexdh_init(m)
return self._parse_kexdh_init(m)
elif not self.transport.server_mode and (ptype == _MSG_KEXDH_REPLY):
return self.parse_kexdh_reply(m)
return self._parse_kexdh_reply(m)
raise SSHException('KexGroup1 asked to handle packet type %d' % ptype)
def parse_kexdh_reply(self, m):
### internals...
def _generate_x(self):
# generate an "x" (1 < x < q), where q is (p-1)/2.
# p is a 128-byte (1024-bit) number, where the first 64 bits are 1.
# therefore q can be approximated as a 2^1023. we drop the subset of
# potential x where the first 63 bits are 1, because some of those will be
# larger than q (but this is a tiny tiny subset of potential x).
while 1:
self.transport.randpool.stir()
x_bytes = self.transport.randpool.get_bytes(128)
x_bytes = chr(ord(x_bytes[0]) & 0x7f) + x_bytes[1:]
if (x_bytes[:8] != '\x7F\xFF\xFF\xFF\xFF\xFF\xFF\xFF') and \
(x_bytes[:8] != '\x00\x00\x00\x00\x00\x00\x00\x00'):
break
self.x = util.inflate_long(x_bytes)
def _parse_kexdh_reply(self, m):
# client mode
host_key = m.get_string()
self.f = m.get_mpint()
@ -98,7 +102,7 @@ class KexGroup1(object):
self.transport._verify_key(host_key, sig)
self.transport._activate_outbound()
def parse_kexdh_init(self, m):
def _parse_kexdh_init(self, m):
# server mode
self.e = m.get_mpint()
if (self.e < 1) or (self.e > P - 1):