Move sasl.py to a directory module and move SCRAM logic to a different file,

move `github/module.py` to `github/__init__.py`
This commit is contained in:
jesopo 2019-02-05 15:54:20 +00:00
parent c311521a31
commit 1fe20a2c98
3 changed files with 98 additions and 55 deletions

View file

@ -1,5 +1,6 @@
import base64, hashlib, hmac, uuid
from src import ModuleManager, utils
from . import scram
def _validate(self, s):
mechanism = s
@ -68,62 +69,17 @@ class Module(ModuleManager.BaseModule):
sasl_username, sasl_password = sasl["args"].split(":", 1)
if event["message"] == "+":
# start SCRAM handshake
first_base = "n=%s,r=%s" % (
_scram_escape(sasl_username), _scram_nonce())
first_withchannel = "n,,%s" % first_base
auth_text = first_withchannel.encode("utf8")
event["server"]._scram_first = first_base.encode("utf8")
event["server"]._scram = scram.SCRAM(
algo, sasl_username, sasl_password)
auth_text = event["server"]._scram.client_first()
print(auth_text)
else:
data = base64.b64decode(event["message"]).decode("utf8")
pieces = dict(piece.split("=", 1) for piece in data.split(","))
if "s" in pieces:
# server-first-message
nonce = pieces["r"].encode("utf8")
salt = base64.b64decode(pieces["s"])
iterations = pieces["i"]
password = sasl_password.encode("utf8")
salted_password = hashlib.pbkdf2_hmac(algo, password, salt,
int(iterations), dklen=None)
event["server"]._scram_salted_password = salted_password
client_key = hmac.digest(salted_password, b"Client Key",
algo)
stored_key = hashlib.new(algo, client_key).digest()
channel = base64.b64encode(b"n,,")
auth_noproof = b"c=%s,r=%s" % (channel, nonce)
auth_message = b"%s,%s,%s" % (event["server"]._scram_first,
data.encode("utf8"), auth_noproof)
event["server"]._scram_auth_message = auth_message
client_signature = hmac.digest(stored_key, auth_message,
algo)
client_proof = base64.b64encode(
_scram_xor(client_key, client_signature))
auth_text = auth_noproof + (b",p=%s" % client_proof)
elif "v" in pieces:
# server-final-message
verifier = pieces["v"]
salted_password = event["server"]._scram_salted_password
auth_message = event["server"]._scram_auth_message
server_key = hmac.digest(salted_password, b"Server Key",
algo)
server_signature = hmac.digest(server_key, auth_message,
algo)
del event["server"]._scram_first
del event["server"]._scram_salted_password
del event["server"]._scram_auth_message
if server_signature != base64.b64decode(verifier):
raise ValueError("SCRAM %s authentication failed "
% algo)
event["server"].disconnect()
auth_text = "+"
current_scram = event["server"]._scram
if current_scram.state == scram.SCRAMState.ClientFirst:
auth_text = current_scram.server_first(event["message"])
elif current_scram.state == scram.SCRAMState.ClientFinal:
auth_text = current_scram.server_final(event["message"])
del event["server"]._scram
else:
raise ValueError("unknown sasl mechanism '%s'" % mechanism)

87
modules/sasl/scram.py Normal file
View file

@ -0,0 +1,87 @@
import base64, enum, hashlib, hmac, uuid
def _scram_nonce():
return uuid.uuid4().hex.encode("utf8")
def _scram_escape(s):
return s.replace(b"=", b"=3D").replace(b",", b"=2C")
def _scram_unescape(s):
return s.replace(b"=3D", b"=").replace(b"=2C", b",")
def _scram_xor(s1, s2):
return bytes(a ^ b for a, b in zip(s1, s2))
class SCRAMState(enum.Enum):
Uninitialised = 0
ClientFirst = 1
ClientFinal = 2
Success = 3
VerifyFailed = 4
class SCRAMError(Exception):
pass
class SCRAM(object):
def __init__(self, algo, username, password):
self._algo = algo
self._username = username.encode("utf8")
self._password = password.encode("utf8")
self.state = SCRAMState.Uninitialised
self._client_first = None
self._salted_password = None
self._auth_message = None
def _get_data(self, message):
data = base64.b64decode(message)
return data, dict(piece.split(b"=", 1) for piece in data.split(b","))
def client_first(self):
self.state = SCRAMState.ClientFirst
# start SCRAM handshake
self._client_first = b"n=%s,r=%s" % (
_scram_escape(self._username), _scram_nonce())
return b"n,,%s" % self._client_first
def server_first(self, message):
self.state = SCRAMState.ClientFinal
data, pieces = self._get_data(message)
# server-first-message
nonce = pieces[b"r"]
salt = base64.b64decode(pieces[b"s"])
iterations = pieces[b"i"]
password = self._password
salted_password = hashlib.pbkdf2_hmac(self._algo, password, salt,
int(iterations), dklen=None)
self._salted_password = salted_password
client_key = hmac.digest(salted_password, b"Client Key", self._algo)
stored_key = hashlib.new(self._algo, client_key).digest()
channel = base64.b64encode(b"n,,")
auth_noproof = b"c=%s,r=%s" % (channel, nonce)
auth_message = b"%s,%s,%s" % (self._client_first, data, auth_noproof)
self._auth_message = auth_message
client_signature = hmac.digest(stored_key, auth_message, self._algo)
client_proof = base64.b64encode(
_scram_xor(client_key, client_signature))
return auth_noproof + (b",p=%s" % client_proof)
def server_final(self, message):
# server-final-message
data, pieces = self._get_data(message)
verifier = pieces[b"v"]
server_key = hmac.digest(self._salted_password, b"Server Key",
self._algo)
server_signature = hmac.digest(server_key, self._auth_message,
self._algo)
if server_signature != base64.b64decode(verifier):
self.state = SCRAMState.VerifyFailed
return None
else:
self.state = SCRAMState.Success
return "+"