"""
passlib.handlers.cisco -- Cisco password hashes
"""
#=============================================================================
# imports
#=============================================================================
# core
from binascii import hexlify, unhexlify
from hashlib import md5
import logging; log = logging.getLogger(__name__)
from warnings import warn
# site
# pkg
from passlib.utils import right_pad_string, to_unicode, repeat_string, to_bytes
from passlib.utils.binary import h64
from passlib.utils.compat import unicode, u, join_byte_values, \
join_byte_elems, iter_byte_values, uascii_to_str
import passlib.utils.handlers as uh
# local
__all__ = [
"cisco_pix",
"cisco_asa",
"cisco_type7",
]
#=============================================================================
# utils
#=============================================================================
#: dummy bytes used by spoil_digest var in cisco_pix._calc_checksum()
_DUMMY_BYTES = b'\xFF' * 32
#=============================================================================
# cisco pix firewall hash
#=============================================================================
class cisco_pix(uh.HasUserContext, uh.StaticHandler):
"""
This class implements the password hash used by older Cisco PIX firewalls,
and follows the :ref:`password-hash-api`.
It does a single round of hashing, and relies on the username
as the salt.
This class only allows passwords <= 16 bytes, anything larger
will result in a :exc:`~passlib.exc.PasswordSizeError` if passed to :meth:`~cisco_pix.hash`,
and be silently rejected if passed to :meth:`~cisco_pix.verify`.
The :meth:`~passlib.ifc.PasswordHash.hash`,
:meth:`~passlib.ifc.PasswordHash.genhash`, and
:meth:`~passlib.ifc.PasswordHash.verify` methods
all support the following extra keyword:
:param str user:
String containing name of user account this password is associated with.
This is *required* in order to correctly hash passwords associated
with a user account on the Cisco device, as it is used to salt
the hash.
Conversely, this *must* be omitted or set to ``""`` in order to correctly
hash passwords which don't have an associated user account
(such as the "enable" password).
.. versionadded:: 1.6
.. versionchanged:: 1.7.1
Passwords > 16 bytes are now rejected / throw error instead of being silently truncated,
to match Cisco behavior. A number of :ref:`bugs <passlib-asa96-bug>` were fixed
which caused prior releases to generate unverifiable hashes in certain cases.
"""
#===================================================================
# class attrs
#===================================================================
#--------------------
# PasswordHash
#--------------------
name = "cisco_pix"
truncate_size = 16
# NOTE: these are the default policy for PasswordHash,
# but want to set them explicitly for now.
truncate_error = True
truncate_verify_reject = True
#--------------------
# GenericHandler
#--------------------
checksum_size = 16
checksum_chars = uh.HASH64_CHARS
#--------------------
# custom
#--------------------
#: control flag signalling "cisco_asa" mode, set by cisco_asa class
_is_asa = False
#===================================================================
# methods
#===================================================================
def _calc_checksum(self, secret):
"""
This function implements the "encrypted" hash format used by Cisco
PIX & ASA. It's behavior has been confirmed for ASA 9.6,
but is presumed correct for PIX & other ASA releases,
as it fits with known test vectors, and existing literature.
While nearly the same, the PIX & ASA hashes have slight differences,
so this function performs differently based on the _is_asa class flag.
Noteable changes from PIX to ASA include password size limit
increased from 16 -> 32, and other internal changes.
"""
# select PIX vs or ASA mode
asa = self._is_asa
#
# encode secret
#
# per ASA 8.4 documentation,
# http://www.cisco.com/c/en/us/td/docs/security/asa/asa84/configuration/guide/asa_84_cli_config/ref_cli.html#Supported_Character_Sets,
# it supposedly uses UTF-8 -- though some double-encoding issues have
# been observed when trying to actually *set* a non-ascii password
# via ASDM, and access via SSH seems to strip 8-bit chars.
#
if isinstance(secret, unicode):
secret = secret.encode("utf-8")
#
# check if password too large
#
# Per ASA 9.6 changes listed in
# http://www.cisco.com/c/en/us/td/docs/security/asa/roadmap/asa_new_features.html,
# prior releases had a maximum limit of 32 characters.
# Testing with an ASA 9.6 system bears this out --
# setting 32-char password for a user account,
# and logins will fail if any chars are appended.
# (ASA 9.6 added new PBKDF2-based hash algorithm,
# which supports larger passwords).
#
# Per PIX documentation
# http://www.cisco.com/en/US/docs/security/pix/pix50/configuration/guide/commands.html,
# it would not allow passwords > 16 chars.
#
# Thus, we unconditionally throw a password size error here,
# as nothing valid can come from a larger password.
# NOTE: assuming PIX has same behavior, but at 16 char limit.
#
spoil_digest = None
if len(secret) > self.truncate_size:
if self.use_defaults:
# called from hash()
msg = "Password too long (%s allows at most %d bytes)" % \
(self.name, self.truncate_size)
raise uh.exc.PasswordSizeError(self.truncate_size, msg=msg)
else:
# called from verify() --
# We don't want to throw error, or return early,
# as that would let attacker know too much. Instead, we set a
# flag to add some dummy data into the md5 digest, so that
# output won't match truncated version of secret, or anything
# else that's fixed and predictable.
spoil_digest = secret + _DUMMY_BYTES
#
# append user to secret
#
# Policy appears to be:
#
# * Nothing appended for enable password (user = "")
#
# * ASA: If user present, but secret is >= 28 chars, nothing appended.
#
# * 1-2 byte users not allowed.
# DEVIATION: we're letting them through, and repeating their
# chars ala 3-char user, to simplify testing.
# Could issue warning in the future though.
#
# * 3 byte user has first char repeated, to pad to 4.
# (observed under ASA 9.6, assuming true elsewhere)
#
# * 4 byte users are used directly.
#
# * 5+ byte users are truncated to 4 bytes.
#
user = self.user
if user:
if isinstance(user, unicode):
user = user.encode("utf-8")
if not asa or len(secret) < 28:
secret += repeat_string(user, 4)
#
# pad / truncate result to limit
#
# While PIX always pads to 16 bytes, ASA increases to 32 bytes IFF
# secret+user > 16 bytes. This makes PIX & ASA have different results
# where secret size in range(13,16), and user is present --
# PIX will truncate to 16, ASA will truncate to 32.
#
if asa and len(secret) > 16:
pad_size = 32
else:
pad_size = 16
secret = right_pad_string(secret, pad_size)
#
# md5 digest
#
if spoil_digest:
# make sure digest won't match truncated version of secret
secret += spoil_digest
digest = md5(secret).digest()
#
# drop every 4th byte
# NOTE: guessing this was done because it makes output exactly
# 16 bytes, which may have been a general 'char password[]'
# size limit under PIX
#
digest = join_byte_elems(c for i, c in enumerate(digest) if (i + 1) & 3)
#
# encode using Hash64
#
return h64.encode_bytes(digest).decode("ascii")
# NOTE: works, but needs UTs.
# @classmethod
# def same_as_pix(cls, secret, user=""):
# """
# test whether (secret + user) combination should
# have the same hash under PIX and ASA.
#
# mainly present to help unittests.
# """
# # see _calc_checksum() above for details of this logic.
# size = len(to_bytes(secret, "utf-8"))
# if user and size < 28:
# size += 4
# return size < 17
#===================================================================
# eoc
#===================================================================
class cisco_asa(cisco_pix):
"""
This class implements the password hash used by Cisco ASA/PIX 7.0 and newer (2005).
Aside from a different internal algorithm, it's use and format is identical
to the older :class:`cisco_pix` class.
For passwords less than 13 characters, this should be identical to :class:`!cisco_pix`,
but will generate a different hash for most larger inputs
(See the `Format & Algorithm`_ section for the details).
This class only allows passwords <= 32 bytes, anything larger
will result in a :exc:`~passlib.exc.PasswordSizeError` if passed to :meth:`~cisco_asa.hash`,
and be silently rejected if passed to :meth:`~cisco_asa.verify`.
.. versionadded:: 1.7
.. versionchanged:: 1.7.1
Passwords > 32 bytes are now rejected / throw error instead of being silently truncated,
to match Cisco behavior. A number of :ref:`bugs <passlib-asa96-bug>` were fixed
which caused prior releases to generate unverifiable hashes in certain cases.
"""
#===================================================================
# class attrs
#===================================================================
#--------------------
# PasswordHash
#--------------------
name = "cisco_asa"
#--------------------
# TruncateMixin
#--------------------
truncate_size = 32
#--------------------
# cisco_pix
#--------------------
_is_asa = True
#===================================================================
# eoc
#===================================================================
#=============================================================================
# type 7
#=============================================================================
class cisco_type7(uh.GenericHandler):
"""
This class implements the "Type 7" password encoding used by Cisco IOS,
and follows the :ref:`password-hash-api`.
It has a simple 4-5 bit salt, but is nonetheless a reversible encoding
instead of a real hash.
The :meth:`~passlib.ifc.PasswordHash.using` method accepts the following optional keywords:
:type salt: int
:param salt:
This may be an optional salt integer drawn from ``range(0,16)``.
If omitted, one will be chosen at random.
:type relaxed: bool
:param relaxed:
By default, providing an invalid value for one of the other
keywords will result in a :exc:`ValueError`. If ``relaxed=True``,
and the error can be corrected, a :exc:`~passlib.exc.PasslibHashWarning`
will be issued instead. Correctable errors include
``salt`` values that are out of range.
Note that while this class outputs digests in upper-case hexadecimal,
it will accept lower-case as well.
This class also provides the following additional method:
.. automethod:: decode
"""
#===================================================================
# class attrs
#===================================================================
#--------------------
# PasswordHash
#--------------------
name = "cisco_type7"
setting_kwds = ("salt",)
#--------------------
# GenericHandler
#--------------------
checksum_chars = uh.UPPER_HEX_CHARS
#--------------------
# HasSalt
#--------------------
# NOTE: encoding could handle max_salt_value=99, but since key is only 52
# chars in size, not sure what appropriate behavior is for that edge case.
min_salt_value = 0
max_salt_value = 52
#===================================================================
# methods
#===================================================================
@classmethod
def using(cls, salt=None, **kwds):
subcls = super(cisco_type7, cls).using(**kwds)
if salt is not None:
salt = subcls._norm_salt(salt, relaxed=kwds.get("relaxed"))
subcls._generate_salt = staticmethod(lambda: salt)
return subcls
@classmethod
def from_string(cls, hash):
hash = to_unicode(hash, "ascii", "hash")
if len(hash) < 2:
raise uh.exc.InvalidHashError(cls)
salt = int(hash[:2]) # may throw ValueError
return cls(salt=salt, checksum=hash[2:].upper())
def __init__(self, salt=None, **kwds):
super(cisco_type7, self).__init__(**kwds)
if salt is not None:
salt = self._norm_salt(salt)
elif self.use_defaults:
salt = self._generate_salt()
assert self._norm_salt(salt) == salt, "generated invalid salt: %r" % (salt,)
else:
raise TypeError("no salt specified")
self.salt = salt
@classmethod
def _norm_salt(cls, salt, relaxed=False):
"""
validate & normalize salt value.
.. note::
the salt for this algorithm is an integer 0-52, not a string
"""
if not isinstance(salt, int):
raise uh.exc.ExpectedTypeError(salt, "integer", "salt")
if 0 <= salt <= cls.max_salt_value:
return salt
msg = "salt/offset must be in 0..52 range"
if relaxed:
warn(msg, uh.PasslibHashWarning)
return 0 if salt < 0 else cls.max_salt_value
else:
raise ValueError(msg)
@staticmethod
def _generate_salt():
return uh.rng.randint(0, 15)
def to_string(self):
return "%02d%s" % (self.salt, uascii_to_str(self.checksum))
def _calc_checksum(self, secret):
# XXX: no idea what unicode policy is, but all examples are
# 7-bit ascii compatible, so using UTF-8
if isinstance(secret, unicode):
secret = secret.encode("utf-8")
return hexlify(self._cipher(secret, self.salt)).decode("ascii").upper()
@classmethod
def decode(cls, hash, encoding="utf-8"):
"""decode hash, returning original password.
:arg hash: encoded password
:param encoding: optional encoding to use (defaults to ``UTF-8``).
:returns: password as unicode
"""
self = cls.from_string(hash)
tmp = unhexlify(self.checksum.encode("ascii"))
raw = self._cipher(tmp, self.salt)
return raw.decode(encoding) if encoding else raw
# type7 uses a xor-based vingere variant, using the following secret key:
_key = u("dsfd;kfoA,.iyewrkldJKDHSUBsgvca69834ncxv9873254k;fg87")
@classmethod
def _cipher(cls, data, salt):
"""xor static key against data - encrypts & decrypts"""
key = cls._key
key_size = len(key)
return join_byte_values(
value ^ ord(key[(salt + idx) % key_size])
for idx, value in enumerate(iter_byte_values(data))
)
#=============================================================================
# eof
#=============================================================================