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airbag/venv/lib/python3.10/site-packages/passlib/handlers/sha2_crypt.py

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"""passlib.handlers.sha2_crypt - SHA256-Crypt / SHA512-Crypt"""
#=============================================================================
# imports
#=============================================================================
# core
import hashlib
import logging; log = logging.getLogger(__name__)
# site
# pkg
from passlib.utils import safe_crypt, test_crypt, \
repeat_string, to_unicode
from passlib.utils.binary import h64
from passlib.utils.compat import byte_elem_value, u, \
uascii_to_str, unicode
import passlib.utils.handlers as uh
# local
__all__ = [
"sha512_crypt",
"sha256_crypt",
]
#=============================================================================
# pure-python backend, used by both sha256_crypt & sha512_crypt
# when crypt.crypt() backend is not available.
#=============================================================================
_BNULL = b'\x00'
# pre-calculated offsets used to speed up C digest stage (see notes below).
# sequence generated using the following:
##perms_order = "p,pp,ps,psp,sp,spp".split(",")
##def offset(i):
## key = (("p" if i % 2 else "") + ("s" if i % 3 else "") +
## ("p" if i % 7 else "") + ("" if i % 2 else "p"))
## return perms_order.index(key)
##_c_digest_offsets = [(offset(i), offset(i+1)) for i in range(0,42,2)]
_c_digest_offsets = (
(0, 3), (5, 1), (5, 3), (1, 2), (5, 1), (5, 3), (1, 3),
(4, 1), (5, 3), (1, 3), (5, 0), (5, 3), (1, 3), (5, 1),
(4, 3), (1, 3), (5, 1), (5, 2), (1, 3), (5, 1), (5, 3),
)
# map used to transpose bytes when encoding final sha256_crypt digest
_256_transpose_map = (
20, 10, 0, 11, 1, 21, 2, 22, 12, 23, 13, 3, 14, 4, 24, 5,
25, 15, 26, 16, 6, 17, 7, 27, 8, 28, 18, 29, 19, 9, 30, 31,
)
# map used to transpose bytes when encoding final sha512_crypt digest
_512_transpose_map = (
42, 21, 0, 1, 43, 22, 23, 2, 44, 45, 24, 3, 4, 46, 25, 26,
5, 47, 48, 27, 6, 7, 49, 28, 29, 8, 50, 51, 30, 9, 10, 52,
31, 32, 11, 53, 54, 33, 12, 13, 55, 34, 35, 14, 56, 57, 36, 15,
16, 58, 37, 38, 17, 59, 60, 39, 18, 19, 61, 40, 41, 20, 62, 63,
)
def _raw_sha2_crypt(pwd, salt, rounds, use_512=False):
"""perform raw sha256-crypt / sha512-crypt
this function provides a pure-python implementation of the internals
for the SHA256-Crypt and SHA512-Crypt algorithms; it doesn't
handle any of the parsing/validation of the hash strings themselves.
:arg pwd: password chars/bytes to hash
:arg salt: salt chars to use
:arg rounds: linear rounds cost
:arg use_512: use sha512-crypt instead of sha256-crypt mode
:returns:
encoded checksum chars
"""
#===================================================================
# init & validate inputs
#===================================================================
# NOTE: the setup portion of this algorithm scales ~linearly in time
# with the size of the password, making it vulnerable to a DOS from
# unreasonably large inputs. the following code has some optimizations
# which would make things even worse, using O(pwd_len**2) memory
# when calculating digest P.
#
# to mitigate these two issues: 1) this code switches to a
# O(pwd_len)-memory algorithm for passwords that are much larger
# than average, and 2) Passlib enforces a library-wide max limit on
# the size of passwords it will allow, to prevent this algorithm and
# others from being DOSed in this way (see passlib.exc.PasswordSizeError
# for details).
# validate secret
if isinstance(pwd, unicode):
# XXX: not sure what official unicode policy is, using this as default
pwd = pwd.encode("utf-8")
assert isinstance(pwd, bytes)
if _BNULL in pwd:
raise uh.exc.NullPasswordError(sha512_crypt if use_512 else sha256_crypt)
pwd_len = len(pwd)
# validate rounds
assert 1000 <= rounds <= 999999999, "invalid rounds"
# NOTE: spec says out-of-range rounds should be clipped, instead of
# causing an error. this function assumes that's been taken care of
# by the handler class.
# validate salt
assert isinstance(salt, unicode), "salt not unicode"
salt = salt.encode("ascii")
salt_len = len(salt)
assert salt_len < 17, "salt too large"
# NOTE: spec says salts larger than 16 bytes should be truncated,
# instead of causing an error. this function assumes that's been
# taken care of by the handler class.
# load sha256/512 specific constants
if use_512:
hash_const = hashlib.sha512
transpose_map = _512_transpose_map
else:
hash_const = hashlib.sha256
transpose_map = _256_transpose_map
#===================================================================
# digest B - used as subinput to digest A
#===================================================================
db = hash_const(pwd + salt + pwd).digest()
#===================================================================
# digest A - used to initialize first round of digest C
#===================================================================
# start out with pwd + salt
a_ctx = hash_const(pwd + salt)
a_ctx_update = a_ctx.update
# add pwd_len bytes of b, repeating b as many times as needed.
a_ctx_update(repeat_string(db, pwd_len))
# for each bit in pwd_len: add b if it's 1, or pwd if it's 0
i = pwd_len
while i:
a_ctx_update(db if i & 1 else pwd)
i >>= 1
# finish A
da = a_ctx.digest()
#===================================================================
# digest P from password - used instead of password itself
# when calculating digest C.
#===================================================================
if pwd_len < 96:
# this method is faster under python, but uses O(pwd_len**2) memory;
# so we don't use it for larger passwords to avoid a potential DOS.
dp = repeat_string(hash_const(pwd * pwd_len).digest(), pwd_len)
else:
# this method is slower under python, but uses a fixed amount of memory.
tmp_ctx = hash_const(pwd)
tmp_ctx_update = tmp_ctx.update
i = pwd_len-1
while i:
tmp_ctx_update(pwd)
i -= 1
dp = repeat_string(tmp_ctx.digest(), pwd_len)
assert len(dp) == pwd_len
#===================================================================
# digest S - used instead of salt itself when calculating digest C
#===================================================================
ds = hash_const(salt * (16 + byte_elem_value(da[0]))).digest()[:salt_len]
assert len(ds) == salt_len, "salt_len somehow > hash_len!"
#===================================================================
# digest C - for a variable number of rounds, combine A, S, and P
# digests in various ways; in order to burn CPU time.
#===================================================================
# NOTE: the original SHA256/512-Crypt specification performs the C digest
# calculation using the following loop:
#
##dc = da
##i = 0
##while i < rounds:
## tmp_ctx = hash_const(dp if i & 1 else dc)
## if i % 3:
## tmp_ctx.update(ds)
## if i % 7:
## tmp_ctx.update(dp)
## tmp_ctx.update(dc if i & 1 else dp)
## dc = tmp_ctx.digest()
## i += 1
#
# The code Passlib uses (below) implements an equivalent algorithm,
# it's just been heavily optimized to pre-calculate a large number
# of things beforehand. It works off of a couple of observations
# about the original algorithm:
#
# 1. each round is a combination of 'dc', 'ds', and 'dp'; determined
# by the whether 'i' a multiple of 2,3, and/or 7.
# 2. since lcm(2,3,7)==42, the series of combinations will repeat
# every 42 rounds.
# 3. even rounds 0-40 consist of 'hash(dc + round-specific-constant)';
# while odd rounds 1-41 consist of hash(round-specific-constant + dc)
#
# Using these observations, the following code...
# * calculates the round-specific combination of ds & dp for each round 0-41
# * runs through as many 42-round blocks as possible
# * runs through as many pairs of rounds as possible for remaining rounds
# * performs once last round if the total rounds should be odd.
#
# this cuts out a lot of the control overhead incurred when running the
# original loop 40,000+ times in python, resulting in ~20% increase in
# speed under CPython (though still 2x slower than glibc crypt)
# prepare the 6 combinations of ds & dp which are needed
# (order of 'perms' must match how _c_digest_offsets was generated)
dp_dp = dp+dp
dp_ds = dp+ds
perms = [dp, dp_dp, dp_ds, dp_ds+dp, ds+dp, ds+dp_dp]
# build up list of even-round & odd-round constants,
# and store in 21-element list as (even,odd) pairs.
data = [ (perms[even], perms[odd]) for even, odd in _c_digest_offsets]
# perform as many full 42-round blocks as possible
dc = da
blocks, tail = divmod(rounds, 42)
while blocks:
for even, odd in data:
dc = hash_const(odd + hash_const(dc + even).digest()).digest()
blocks -= 1
# perform any leftover rounds
if tail:
# perform any pairs of rounds
pairs = tail>>1
for even, odd in data[:pairs]:
dc = hash_const(odd + hash_const(dc + even).digest()).digest()
# if rounds was odd, do one last round (since we started at 0,
# last round will be an even-numbered round)
if tail & 1:
dc = hash_const(dc + data[pairs][0]).digest()
#===================================================================
# encode digest using appropriate transpose map
#===================================================================
return h64.encode_transposed_bytes(dc, transpose_map).decode("ascii")
#=============================================================================
# handlers
#=============================================================================
_UROUNDS = u("rounds=")
_UDOLLAR = u("$")
_UZERO = u("0")
class _SHA2_Common(uh.HasManyBackends, uh.HasRounds, uh.HasSalt,
uh.GenericHandler):
"""class containing common code shared by sha256_crypt & sha512_crypt"""
#===================================================================
# class attrs
#===================================================================
# name - set by subclass
setting_kwds = ("salt", "rounds", "implicit_rounds", "salt_size")
# ident - set by subclass
checksum_chars = uh.HASH64_CHARS
# checksum_size - set by subclass
max_salt_size = 16
salt_chars = uh.HASH64_CHARS
min_rounds = 1000 # bounds set by spec
max_rounds = 999999999 # bounds set by spec
rounds_cost = "linear"
_cdb_use_512 = False # flag for _calc_digest_builtin()
_rounds_prefix = None # ident + _UROUNDS
#===================================================================
# methods
#===================================================================
implicit_rounds = False
def __init__(self, implicit_rounds=None, **kwds):
super(_SHA2_Common, self).__init__(**kwds)
# if user calls hash() w/ 5000 rounds, default to compact form.
if implicit_rounds is None:
implicit_rounds = (self.use_defaults and self.rounds == 5000)
self.implicit_rounds = implicit_rounds
def _parse_salt(self, salt):
# required per SHA2-crypt spec -- truncate config salts rather than throwing error
return self._norm_salt(salt, relaxed=self.checksum is None)
def _parse_rounds(self, rounds):
# required per SHA2-crypt spec -- clip config rounds rather than throwing error
return self._norm_rounds(rounds, relaxed=self.checksum is None)
@classmethod
def from_string(cls, hash):
# basic format this parses -
# $5$[rounds=<rounds>$]<salt>[$<checksum>]
# TODO: this *could* use uh.parse_mc3(), except that the rounds
# portion has a slightly different grammar.
# convert to unicode, check for ident prefix, split on dollar signs.
hash = to_unicode(hash, "ascii", "hash")
ident = cls.ident
if not hash.startswith(ident):
raise uh.exc.InvalidHashError(cls)
assert len(ident) == 3
parts = hash[3:].split(_UDOLLAR)
# extract rounds value
if parts[0].startswith(_UROUNDS):
assert len(_UROUNDS) == 7
rounds = parts.pop(0)[7:]
if rounds.startswith(_UZERO) and rounds != _UZERO:
raise uh.exc.ZeroPaddedRoundsError(cls)
rounds = int(rounds)
implicit_rounds = False
else:
rounds = 5000
implicit_rounds = True
# rest should be salt and checksum
if len(parts) == 2:
salt, chk = parts
elif len(parts) == 1:
salt = parts[0]
chk = None
else:
raise uh.exc.MalformedHashError(cls)
# return new object
return cls(
rounds=rounds,
salt=salt,
checksum=chk or None,
implicit_rounds=implicit_rounds,
)
def to_string(self):
if self.rounds == 5000 and self.implicit_rounds:
hash = u("%s%s$%s") % (self.ident, self.salt,
self.checksum or u(''))
else:
hash = u("%srounds=%d$%s$%s") % (self.ident, self.rounds,
self.salt, self.checksum or u(''))
return uascii_to_str(hash)
#===================================================================
# backends
#===================================================================
backends = ("os_crypt", "builtin")
#---------------------------------------------------------------
# os_crypt backend
#---------------------------------------------------------------
#: test hash for OS detection -- provided by subclass
_test_hash = None
@classmethod
def _load_backend_os_crypt(cls):
if test_crypt(*cls._test_hash):
cls._set_calc_checksum_backend(cls._calc_checksum_os_crypt)
return True
else:
return False
def _calc_checksum_os_crypt(self, secret):
config = self.to_string()
hash = safe_crypt(secret, config)
if hash is None:
# py3's crypt.crypt() can't handle non-utf8 bytes.
# fallback to builtin alg, which is always available.
return self._calc_checksum_builtin(secret)
# NOTE: avoiding full parsing routine via from_string().checksum,
# and just extracting the bit we need.
cs = self.checksum_size
if not hash.startswith(self.ident) or hash[-cs-1] != _UDOLLAR:
raise uh.exc.CryptBackendError(self, config, hash)
return hash[-cs:]
#---------------------------------------------------------------
# builtin backend
#---------------------------------------------------------------
@classmethod
def _load_backend_builtin(cls):
cls._set_calc_checksum_backend(cls._calc_checksum_builtin)
return True
def _calc_checksum_builtin(self, secret):
return _raw_sha2_crypt(secret, self.salt, self.rounds,
self._cdb_use_512)
#===================================================================
# eoc
#===================================================================
class sha256_crypt(_SHA2_Common):
"""This class implements the SHA256-Crypt password hash, and follows the :ref:`password-hash-api`.
It supports a variable-length salt, and a variable number of rounds.
The :meth:`~passlib.ifc.PasswordHash.using` method accepts the following optional keywords:
:type salt: str
:param salt:
Optional salt string.
If not specified, one will be autogenerated (this is recommended).
If specified, it must be 0-16 characters, drawn from the regexp range ``[./0-9A-Za-z]``.
:type rounds: int
:param rounds:
Optional number of rounds to use.
Defaults to 535000, must be between 1000 and 999999999, inclusive.
.. note::
per the official specification, when the rounds parameter is set to 5000,
it may be omitted from the hash string.
: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 ``rounds``
that are too small or too large, and ``salt`` strings that are too long.
.. versionadded:: 1.6
..
commented out, currently only supported by :meth:`hash`, and not via :meth:`using`:
:type implicit_rounds: bool
:param implicit_rounds:
this is an internal option which generally doesn't need to be touched.
this flag determines whether the hash should omit the rounds parameter
when encoding it to a string; this is only permitted by the spec for rounds=5000,
and the flag is ignored otherwise. the spec requires the two different
encodings be preserved as they are, instead of normalizing them.
"""
#===================================================================
# class attrs
#===================================================================
name = "sha256_crypt"
ident = u("$5$")
checksum_size = 43
# NOTE: using 25/75 weighting of builtin & os_crypt backends
default_rounds = 535000
#===================================================================
# backends
#===================================================================
_test_hash = ("test", "$5$rounds=1000$test$QmQADEXMG8POI5W"
"Dsaeho0P36yK3Tcrgboabng6bkb/")
#===================================================================
# eoc
#===================================================================
#=============================================================================
# sha 512 crypt
#=============================================================================
class sha512_crypt(_SHA2_Common):
"""This class implements the SHA512-Crypt password hash, and follows the :ref:`password-hash-api`.
It supports a variable-length salt, and a variable number of rounds.
The :meth:`~passlib.ifc.PasswordHash.using` method accepts the following optional keywords:
:type salt: str
:param salt:
Optional salt string.
If not specified, one will be autogenerated (this is recommended).
If specified, it must be 0-16 characters, drawn from the regexp range ``[./0-9A-Za-z]``.
:type rounds: int
:param rounds:
Optional number of rounds to use.
Defaults to 656000, must be between 1000 and 999999999, inclusive.
.. note::
per the official specification, when the rounds parameter is set to 5000,
it may be omitted from the hash string.
: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 ``rounds``
that are too small or too large, and ``salt`` strings that are too long.
.. versionadded:: 1.6
..
commented out, currently only supported by :meth:`hash`, and not via :meth:`using`:
:type implicit_rounds: bool
:param implicit_rounds:
this is an internal option which generally doesn't need to be touched.
this flag determines whether the hash should omit the rounds parameter
when encoding it to a string; this is only permitted by the spec for rounds=5000,
and the flag is ignored otherwise. the spec requires the two different
encodings be preserved as they are, instead of normalizing them.
"""
#===================================================================
# class attrs
#===================================================================
name = "sha512_crypt"
ident = u("$6$")
checksum_size = 86
_cdb_use_512 = True
# NOTE: using 25/75 weighting of builtin & os_crypt backends
default_rounds = 656000
#===================================================================
# backend
#===================================================================
_test_hash = ("test", "$6$rounds=1000$test$2M/Lx6Mtobqj"
"Ljobw0Wmo4Q5OFx5nVLJvmgseatA6oMn"
"yWeBdRDx4DU.1H3eGmse6pgsOgDisWBG"
"I5c7TZauS0")
#===================================================================
# eoc
#===================================================================
#=============================================================================
# eof
#=============================================================================
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