def encrypt(self, session):
"""
Return an encrypted reference to the session. The encrypted
identifier will be stored in the session for verification
and caching. Therefore, further calls to this method will reuse
the previously cached identifier.
"""
if 'encrypted_id' not in session:
# .cache_key is a very good property since it ensures
# that the cache is actually created, and works from first
# request
session_id = session.cache_key
# since it always starts with the backend module name
# and __init__() expects pure id, we can strip that
assert(session_id.startswith(self.cache_key_prefix))
session_id = session_id[len(self.cache_key_prefix):]
assert(len(session_id) == self.session_id_length)
# now's another curious trick: session id consists
# of [a-z][0-9]. it's basically base36 but since decoding
# that is harsh, let's just treat it as base64. that's
# going to pack it into 3/4 original size, that is 24 bytes.
# then, with random prefix prepended we will fit into one
# block of ciphertext less.
session_id = ub64decode(session_id)
data = (cipher.rng.read(self.random_prefix_bytes)
+ session_id)
assert(len(data) == self.ciphertext_length)
session['encrypted_id'] = ub64encode(
cipher.encrypt(data))
session.save()
return session['encrypted_id']
def decrypt(self, eid):
"""
Return the SessionStore to which the encrypted identifier is
pointing. Raises ValueError if the identifier is invalid.
"""
try:
session_id = cipher.decrypt(ub64decode(eid),
self.ciphertext_length)
except (TypeError, ValueError):
pass
else:
session_id = session_id[self.random_prefix_bytes:]
session_id = ub64encode(session_id)
session = SessionStore(session_key=session_id)
if session.get('encrypted_id') == eid:
# circular import
from .models import RevokedToken
# revoke to prevent replay attacks
if RevokedToken.add(eid):
del session['encrypted_id']
session.save()
return session
raise ValueError('Invalid session id')
def encrypt(self, session):
"""
Return an encrypted reference to the session. The encrypted
identifier will be stored in the session for verification
and caching. Therefore, further calls to this method will reuse
the previously cached identifier.
"""
if 'encrypted_id' not in session:
# .cache_key is a very good property since it ensures
# that the cache is actually created, and works from first
# request
session_id = session.cache_key
# since it always starts with the backend module name
# and __init__() expects pure id, we can strip that
assert (session_id.startswith(self.cache_key_prefix))
session_id = session_id[len(self.cache_key_prefix):]
assert (len(session_id) == self.session_id_length)
# now's another curious trick: session id consists
# of [a-z][0-9]. it's basically base36 but since decoding
# that is harsh, let's just treat it as base64. that's
# going to pack it into 3/4 original size, that is 24 bytes.
# then, with random prefix prepended we will fit into one
# block of ciphertext less.
session_id = ub64decode(session_id)
data = (cipher.rng.read(self.random_prefix_bytes) + session_id)
assert (len(data) == self.ciphertext_length)
session['encrypted_id'] = ub64encode(cipher.encrypt(data))
session.save()
return session['encrypted_id']
def decrypt(self, eid):
"""
Return the SessionStore to which the encrypted identifier is
pointing. Raises ValueError if the identifier is invalid.
"""
try:
session_id = cipher.decrypt(ub64decode(eid),
self.ciphertext_length)
except (TypeError, ValueError):
pass
else:
session_id = session_id[self.random_prefix_bytes:]
session_id = ub64encode(session_id)
session = SessionStore(session_key=session_id)
if session.get('encrypted_id') == eid:
# circular import
from .models import RevokedToken
# revoke to prevent replay attacks
if RevokedToken.add(eid):
del session['encrypted_id']
session.save()
return session
raise ValueError('Invalid session id')
def decrypt(self, eid):
byte_eid = ub64decode(eid)
byte_id = cipher.decrypt(byte_eid, 4)
id = struct.unpack('!I', byte_id)[0]
return id
def decrypt(self, eid):
byte_eid = ub64decode(eid)
byte_id = cipher.decrypt(byte_eid, 4)
id = struct.unpack('!I', byte_id)[0]
return id