diff options
| -rw-r--r-- | paramiko/kex_nistp256.py | 102 | ||||
| -rw-r--r-- | paramiko/kex_nistp384.py | 9 | ||||
| -rw-r--r-- | paramiko/kex_nistp521.py | 9 |
3 files changed, 120 insertions, 0 deletions
diff --git a/paramiko/kex_nistp256.py b/paramiko/kex_nistp256.py new file mode 100644 index 00000000..4b7552c8 --- /dev/null +++ b/paramiko/kex_nistp256.py @@ -0,0 +1,102 @@ +""" +Ephemeral Elliptic Curve Diffie-Hellman (ECDH) key exchange +RFC 5656, Section 4 +""" + +from hashlib import sha256 +from paramiko.message import Message +from paramiko.py3compat import byte_chr, long +from paramiko.ssh_exception import SSHException +from cryptography.hazmat.backends import default_backend +from cryptography.hazmat.primitives.asymmetric import ec + + +_MSG_KEXECDH_INIT, _MSG_KEXECDH_REPLY = range(30, 32) +c_MSG_KEXECDH_INIT, c_MSG_KEXECDH_REPLY = [byte_chr(c) for c in range(30, 32)] + + +class KexNistp256(): + + name = "ecdh-sha2-nistp256" + hash_algo = sha256 + curve = ec.SECP256R1() + + def __init__(self, transport): + self.transport = transport + #private key, client public and server public keys + self.P = long(0) + self.Q_C = None + self.Q_S = None + + def start_kex(self): + self._generate_key_pair() + if self.transport.server_mode: + self.transport._expect_packet(_MSG_KEXECDH_INIT) + return + m = Message() + m.add_byte(c_MSG_KEXECDH_INIT) + #SEC1: V2.0 2.3.3 Elliptic-Curve-Point-to-Octet-String Conversion + m.add_string(self.Q_C.public_numbers().encode_point()) + self.transport._send_message(m) + self.transport._expect_packet(_MSG_KEXECDH_REPLY) + + def parse_next(self, ptype, m): + if self.transport.server_mode and (ptype == _MSG_KEXECDH_INIT): + return self._parse_kexecdh_init(m) + elif not self.transport.server_mode and (ptype == _MSG_KEXECDH_REPLY): + return self._parse_kexecdh_reply(m) + raise SSHException('KexECDH asked to handle packet type %d' % ptype) + + def _generate_key_pair(self): + self.P = ec.generate_private_key(self.curve, default_backend()) + if self.transport.server_mode: + self.Q_S = self.P.public_key() + return + self.Q_C = self.P.public_key() + + def _parse_kexecdh_init(self, m): + Q_C_bytes = m.get_string() + self.Q_C = ec.EllipticCurvePublicNumbers.from_encoded_point(self.curve, Q_C_bytes) + K_S = self.transport.get_server_key().asbytes() + K = self.P.exchange(ec.ECDH(), self.Q_C.public_key(default_backend())) + K = long(K.encode('hex'), 16) + #compute exchange hash + hm = Message() + hm.add(self.transport.remote_version, self.transport.local_version, + self.transport.remote_kex_init, self.transport.local_kex_init) + hm.add_string(K_S) + hm.add_string(Q_C_bytes) + #SEC1: V2.0 2.3.3 Elliptic-Curve-Point-to-Octet-String Conversion + hm.add_string(self.Q_S.public_numbers().encode_point()) + hm.add_mpint(long(K)) + H = self.hash_algo(hm.asbytes()).digest() + self.transport._set_K_H(K, H) + sig = self.transport.get_server_key().sign_ssh_data(H) + #construct reply + m = Message() + m.add_byte(c_MSG_KEXECDH_REPLY) + m.add_string(K_S) + m.add_string(self.Q_S.public_numbers().encode_point()) + m.add_string(sig) + self.transport._send_message(m) + self.transport._activate_outbound() + + def _parse_kexecdh_reply(self, m): + K_S = m.get_string() + Q_S_bytes = m.get_string() + self.Q_S = ec.EllipticCurvePublicNumbers.from_encoded_point(self.curve, Q_S_bytes) + sig = m.get_binary() + K = self.P.exchange(ec.ECDH(), self.Q_S.public_key(default_backend())) + K = long(K.encode('hex'), 16) + #compute exchange hash and verify signature + hm = Message() + hm.add(self.transport.local_version, self.transport.remote_version, + self.transport.local_kex_init, self.transport.remote_kex_init) + hm.add_string(K_S) + #SEC1: V2.0 2.3.3 Elliptic-Curve-Point-to-Octet-String Conversion + hm.add_string(self.Q_C.public_numbers().encode_point()) + hm.add_string(Q_S_bytes) + hm.add_mpint(K) + self.transport._set_K_H(K, self.hash_algo(hm.asbytes()).digest()) + self.transport._verify_key(K_S, sig) + self.transport._activate_outbound() diff --git a/paramiko/kex_nistp384.py b/paramiko/kex_nistp384.py new file mode 100644 index 00000000..cdd23a5e --- /dev/null +++ b/paramiko/kex_nistp384.py @@ -0,0 +1,9 @@ +from hashlib import sha384 +from paramiko.kex_nistp256 import KexNistp256 +from cryptography.hazmat.primitives.asymmetric import ec + + +class KexNistp384(KexNistp256): + name = "ecdh-sha2-nistp384" + hash_algo = sha384 + curve = ec.SECP384R1() diff --git a/paramiko/kex_nistp521.py b/paramiko/kex_nistp521.py new file mode 100644 index 00000000..352fe8c9 --- /dev/null +++ b/paramiko/kex_nistp521.py @@ -0,0 +1,9 @@ +from hashlib import sha512 +from paramiko.kex_nistp256 import KexNistp256 +from cryptography.hazmat.primitives.asymmetric import ec + + +class KexNistp521(KexNistp256): + name = "ecdh-sha2-nistp521" + hash_algo = sha512 + curve = ec.SECP521R1() |