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81 lines
3.0 KiB
81 lines
3.0 KiB
from __future__ import absolute_import
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import base64
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import hashlib
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import hmac
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import uuid
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from kafka.vendor import six
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if six.PY2:
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def xor_bytes(left, right):
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return bytearray(ord(lb) ^ ord(rb) for lb, rb in zip(left, right))
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else:
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def xor_bytes(left, right):
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return bytes(lb ^ rb for lb, rb in zip(left, right))
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class ScramClient:
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MECHANISMS = {
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'SCRAM-SHA-256': hashlib.sha256,
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'SCRAM-SHA-512': hashlib.sha512
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}
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def __init__(self, user, password, mechanism):
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self.nonce = str(uuid.uuid4()).replace('-', '')
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self.auth_message = ''
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self.salted_password = None
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self.user = user
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self.password = password.encode('utf-8')
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self.hashfunc = self.MECHANISMS[mechanism]
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self.hashname = ''.join(mechanism.lower().split('-')[1:3])
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self.stored_key = None
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self.client_key = None
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self.client_signature = None
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self.client_proof = None
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self.server_key = None
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self.server_signature = None
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def first_message(self):
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client_first_bare = 'n={},r={}'.format(self.user, self.nonce)
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self.auth_message += client_first_bare
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return 'n,,' + client_first_bare
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def process_server_first_message(self, server_first_message):
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self.auth_message += ',' + server_first_message
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params = dict(pair.split('=', 1) for pair in server_first_message.split(','))
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server_nonce = params['r']
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if not server_nonce.startswith(self.nonce):
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raise ValueError("Server nonce, did not start with client nonce!")
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self.nonce = server_nonce
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self.auth_message += ',c=biws,r=' + self.nonce
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salt = base64.b64decode(params['s'].encode('utf-8'))
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iterations = int(params['i'])
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self.create_salted_password(salt, iterations)
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self.client_key = self.hmac(self.salted_password, b'Client Key')
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self.stored_key = self.hashfunc(self.client_key).digest()
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self.client_signature = self.hmac(self.stored_key, self.auth_message.encode('utf-8'))
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self.client_proof = xor_bytes(self.client_key, self.client_signature)
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self.server_key = self.hmac(self.salted_password, b'Server Key')
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self.server_signature = self.hmac(self.server_key, self.auth_message.encode('utf-8'))
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def hmac(self, key, msg):
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return hmac.new(key, msg, digestmod=self.hashfunc).digest()
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def create_salted_password(self, salt, iterations):
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self.salted_password = hashlib.pbkdf2_hmac(
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self.hashname, self.password, salt, iterations
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)
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def final_message(self):
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return 'c=biws,r={},p={}'.format(self.nonce, base64.b64encode(self.client_proof).decode('utf-8'))
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def process_server_final_message(self, server_final_message):
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params = dict(pair.split('=', 1) for pair in server_final_message.split(','))
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if self.server_signature != base64.b64decode(params['v'].encode('utf-8')):
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raise ValueError("Server sent wrong signature!")
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