paramiko.kex

40 - 41 name = 'diffie-hellman-group1-sha1' - 42 -

43 - def __init__(self, transport): -

44 self.transport = transport - 45 self.x = 0L - 46 self.e = 0L - 47 self.f = 0L -

48 -

49 - def start_kex(self): -

50 self._generate_x() - 51 if self.transport.server_mode: - 52 # compute f = g^x mod p, but don't send it yet - 53 self.f = pow(G, self.x, P) - 54 self.transport._expect_packet(_MSG_KEXDH_INIT) - 55 return - 56 # compute e = g^x mod p (where g=2), and send it - 57 self.e = pow(G, self.x, P) - 58 m = Message() - 59 m.add_byte(chr(_MSG_KEXDH_INIT)) - 60 m.add_mpint(self.e) - 61 self.transport._send_message(m) - 62 self.transport._expect_packet(_MSG_KEXDH_REPLY) -

63 -

64 - def parse_next(self, ptype, m): -

65 if self.transport.server_mode and (ptype == _MSG_KEXDH_INIT): - 66 return self._parse_kexdh_init(m) - 67 elif not self.transport.server_mode and (ptype == _MSG_KEXDH_REPLY): - 68 return self._parse_kexdh_reply(m) - 69 raise SSHException('KexGroup1 asked to handle packet type %d' % ptype) -

70 - 71 - 72 ### internals... - 73 - 74 -

75 - def _generate_x(self): -

76 # generate an "x" (1 < x < q), where q is (p-1)/2. - 77 # p is a 128-byte (1024-bit) number, where the first 64 bits are 1. - 78 # therefore q can be approximated as a 2^1023. we drop the subset of - 79 # potential x where the first 63 bits are 1, because some of those will be - 80 # larger than q (but this is a tiny tiny subset of potential x). - 81 while 1: - 82 x_bytes = self.transport.rng.read(128) - 83 x_bytes = chr(ord(x_bytes[0]) & 0x7f) + x_bytes[1:] - 84 if (x_bytes[:8] != '\x7F\xFF\xFF\xFF\xFF\xFF\xFF\xFF') and \ - 85 (x_bytes[:8] != '\x00\x00\x00\x00\x00\x00\x00\x00'): - 86 break - 87 self.x = util.inflate_long(x_bytes) -

88 -

89 - def _parse_kexdh_reply(self, m): -

90 # client mode - 91 host_key = m.get_string() - 92 self.f = m.get_mpint() - 93 if (self.f < 1) or (self.f > P - 1): - 94 raise SSHException('Server kex "f" is out of range') - 95 sig = m.get_string() - 96 K = pow(self.f, self.x, P) - 97 # okay, build up the hash H of (V_C || V_S || I_C || I_S || K_S || e || f || K) - 98 hm = Message() - 99 hm.add(self.transport.local_version, self.transport.remote_version, -100 self.transport.local_kex_init, self.transport.remote_kex_init) -101 hm.add_string(host_key) -102 hm.add_mpint(self.e) -103 hm.add_mpint(self.f) -104 hm.add_mpint(K) -105 self.transport._set_K_H(K, SHA.new(str(hm)).digest()) -106 self.transport._verify_key(host_key, sig) -107 self.transport._activate_outbound() -

108 -

109 - def _parse_kexdh_init(self, m): -

110 # server mode -111 self.e = m.get_mpint() -112 if (self.e < 1) or (self.e > P - 1): -113 raise SSHException('Client kex "e" is out of range') -114 K = pow(self.e, self.x, P) -115 key = str(self.transport.get_server_key()) -116 # okay, build up the hash H of (V_C || V_S || I_C || I_S || K_S || e || f || K) -117 hm = Message() -118 hm.add(self.transport.remote_version, self.transport.local_version, -119 self.transport.remote_kex_init, self.transport.local_kex_init) -120 hm.add_string(key) -121 hm.add_mpint(self.e) -122 hm.add_mpint(self.f) -123 hm.add_mpint(K) -124 H = SHA.new(str(hm)).digest() -125 self.transport._set_K_H(K, H) -126 # sign it -127 sig = self.transport.get_server_key().sign_ssh_data(self.transport.rng, H) -128 # send reply -129 m = Message() -130 m.add_byte(chr(_MSG_KEXDH_REPLY)) -131 m.add_string(key) -132 m.add_mpint(self.f) -133 m.add_string(str(sig)) -134 self.transport._send_message(m) -135 self.transport._activate_outbound() -

Source Code for Module paramiko.kex_group1