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