def kdf_tor(shared_secret):
t = shared_secret + bytes([0])
computed_auth = sha1(t)
key_material = b''
for i in range(1, 5):
t = shared_secret + bytes([i])
tsh = sha1(t)
key_material += tsh
return computed_auth, key_material
def _decrypt_basic(self, descriptor_cookie):
assert self._crypted_data[0] == AuthType.Basic
block_count = self._crypted_data[1]
entries_len = block_count * self.REND_BASIC_AUTH_CLIENT_MULTIPLE * self.REND_BASIC_AUTH_CLIENT_ENTRY_LEN
assert len(self._crypted_data) > 2 + entries_len + self.CIPHER_IV_LEN, 'Size of crypted data too small'
iv = self._crypted_data[2 + entries_len:2 + entries_len + self.CIPHER_IV_LEN]
client_id = sha1(descriptor_cookie + iv)[:4]
session_key = self._get_session_key(self._crypted_data[2:2 + entries_len], descriptor_cookie, client_id)
d = aes_ctr_decryptor(session_key, iv)
data = self._crypted_data[2 + entries_len + self.CIPHER_IV_LEN:]
return d.update(data)
def _get_secret_id(self, replica):
"""
Get secret_id by replica number.
rend-spec.txt
1.3.
"time-period" changes periodically as a function of time and
"permanent-id". The current value for "time-period" can be calculated
using the following formula:
time-period = (current-time + permanent-id-byte * 86400 / 256)
/ 86400
"""
# tor ref: get_secret_id_part_bytes
permanent_byte = self.permanent_id[0]
time_period = int((int(time.time()) + (permanent_byte * 86400 / 256)) / 86400)
if self._descriptor_cookie and self._auth_type == AuthType.Stealth:
buff = struct.pack('!I16sB', time_period, self._descriptor_cookie, replica)
else:
buff = struct.pack('!IB', time_period, replica)
return sha1(buff)
def _serialize_payload(self):
# PK_ID Identifier for Bob's PK [20 octets]
return struct.pack('!20s', sha1(
self.introduction_point.service_key)) + self.handshake_encrypted
def get_descriptor_id(self, replica):
# tor ref: rend_compute_v2_desc_id
secret_id = self._get_secret_id(replica)
buff = self.permanent_id + secret_id
return sha1(buff)
def tor_digest(msg):
return sha1(msg)
def get_descriptor_id(self, replica):
# tor ref: rend_compute_v2_desc_id
# Calculate descriptor ID: H(permanent-id | secret-id-part)
buff = self._permanent_id + self._get_secret_id(replica)
return sha1(buff)