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1244 lines
52 KiB
1244 lines
52 KiB
"""passlib.bcrypt -- implementation of OpenBSD's BCrypt algorithm.
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TODO:
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* support 2x and altered-2a hashes?
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http://www.openwall.com/lists/oss-security/2011/06/27/9
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* deal with lack of PY3-compatibile c-ext implementation
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"""
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#=============================================================================
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# imports
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#=============================================================================
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from __future__ import with_statement, absolute_import
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# core
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from base64 import b64encode
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from hashlib import sha256
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import os
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import re
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import logging; log = logging.getLogger(__name__)
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from warnings import warn
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# site
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_bcrypt = None # dynamically imported by _load_backend_bcrypt()
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_pybcrypt = None # dynamically imported by _load_backend_pybcrypt()
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_bcryptor = None # dynamically imported by _load_backend_bcryptor()
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# pkg
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_builtin_bcrypt = None # dynamically imported by _load_backend_builtin()
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from passlib.crypto.digest import compile_hmac
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from passlib.exc import PasslibHashWarning, PasslibSecurityWarning, PasslibSecurityError
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from passlib.utils import safe_crypt, repeat_string, to_bytes, parse_version, \
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rng, getrandstr, test_crypt, to_unicode, \
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utf8_truncate, utf8_repeat_string, crypt_accepts_bytes
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from passlib.utils.binary import bcrypt64
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from passlib.utils.compat import get_unbound_method_function
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from passlib.utils.compat import u, uascii_to_str, unicode, str_to_uascii, PY3, error_from
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import passlib.utils.handlers as uh
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# local
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__all__ = [
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"bcrypt",
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]
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#=============================================================================
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# support funcs & constants
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#=============================================================================
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IDENT_2 = u("$2$")
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IDENT_2A = u("$2a$")
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IDENT_2X = u("$2x$")
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IDENT_2Y = u("$2y$")
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IDENT_2B = u("$2b$")
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_BNULL = b'\x00'
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# reference hash of "test", used in various self-checks
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TEST_HASH_2A = "$2a$04$5BJqKfqMQvV7nS.yUguNcueVirQqDBGaLXSqj.rs.pZPlNR0UX/HK"
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def _detect_pybcrypt():
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"""
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internal helper which tries to distinguish pybcrypt vs bcrypt.
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:returns:
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True if cext-based py-bcrypt,
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False if ffi-based bcrypt,
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None if 'bcrypt' module not found.
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.. versionchanged:: 1.6.3
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Now assuming bcrypt installed, unless py-bcrypt explicitly detected.
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Previous releases assumed py-bcrypt by default.
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Making this change since py-bcrypt is (apparently) unmaintained and static,
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whereas bcrypt is being actively maintained, and it's internal structure may shift.
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"""
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# NOTE: this is also used by the unittests.
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# check for module.
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try:
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import bcrypt
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except ImportError:
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# XXX: this is ignoring case where py-bcrypt's "bcrypt._bcrypt" C Ext fails to import;
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# would need to inspect actual ImportError message to catch that.
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return None
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# py-bcrypt has a "._bcrypt.__version__" attribute (confirmed for v0.1 - 0.4),
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# which bcrypt lacks (confirmed for v1.0 - 2.0)
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# "._bcrypt" alone isn't sufficient, since bcrypt 2.0 now has that attribute.
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try:
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from bcrypt._bcrypt import __version__
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except ImportError:
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return False
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return True
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#=============================================================================
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# backend mixins
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#=============================================================================
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class _BcryptCommon(uh.SubclassBackendMixin, uh.TruncateMixin, uh.HasManyIdents,
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uh.HasRounds, uh.HasSalt, uh.GenericHandler):
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"""
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Base class which implements brunt of BCrypt code.
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This is then subclassed by the various backends,
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to override w/ backend-specific methods.
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When a backend is loaded, the bases of the 'bcrypt' class proper
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are modified to prepend the correct backend-specific subclass.
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"""
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#===================================================================
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# class attrs
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#===================================================================
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#--------------------
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# PasswordHash
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#--------------------
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name = "bcrypt"
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setting_kwds = ("salt", "rounds", "ident", "truncate_error")
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#--------------------
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# GenericHandler
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#--------------------
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checksum_size = 31
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checksum_chars = bcrypt64.charmap
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#--------------------
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# HasManyIdents
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#--------------------
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default_ident = IDENT_2B
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ident_values = (IDENT_2, IDENT_2A, IDENT_2X, IDENT_2Y, IDENT_2B)
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ident_aliases = {u("2"): IDENT_2, u("2a"): IDENT_2A, u("2y"): IDENT_2Y,
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u("2b"): IDENT_2B}
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#--------------------
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# HasSalt
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#--------------------
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min_salt_size = max_salt_size = 22
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salt_chars = bcrypt64.charmap
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# NOTE: 22nd salt char must be in restricted set of ``final_salt_chars``, not full set above.
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final_salt_chars = ".Oeu" # bcrypt64._padinfo2[1]
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#--------------------
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# HasRounds
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#--------------------
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default_rounds = 12 # current passlib default
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min_rounds = 4 # minimum from bcrypt specification
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max_rounds = 31 # 32-bit integer limit (since real_rounds=1<<rounds)
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rounds_cost = "log2"
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#--------------------
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# TruncateMixin
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#--------------------
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truncate_size = 72
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#--------------------
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# custom
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#--------------------
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# backend workaround detection flags
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# NOTE: these are only set on the backend mixin classes
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_workrounds_initialized = False
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_has_2a_wraparound_bug = False
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_lacks_20_support = False
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_lacks_2y_support = False
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_lacks_2b_support = False
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_fallback_ident = IDENT_2A
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_require_valid_utf8_bytes = False
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#===================================================================
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# formatting
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#===================================================================
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@classmethod
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def from_string(cls, hash):
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ident, tail = cls._parse_ident(hash)
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if ident == IDENT_2X:
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raise ValueError("crypt_blowfish's buggy '2x' hashes are not "
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"currently supported")
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rounds_str, data = tail.split(u("$"))
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rounds = int(rounds_str)
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if rounds_str != u('%02d') % (rounds,):
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raise uh.exc.MalformedHashError(cls, "malformed cost field")
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salt, chk = data[:22], data[22:]
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return cls(
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rounds=rounds,
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salt=salt,
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checksum=chk or None,
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ident=ident,
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)
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def to_string(self):
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hash = u("%s%02d$%s%s") % (self.ident, self.rounds, self.salt, self.checksum)
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return uascii_to_str(hash)
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# NOTE: this should be kept separate from to_string()
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# so that bcrypt_sha256() can still use it, while overriding to_string()
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def _get_config(self, ident):
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"""internal helper to prepare config string for backends"""
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config = u("%s%02d$%s") % (ident, self.rounds, self.salt)
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return uascii_to_str(config)
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#===================================================================
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# migration
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#===================================================================
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@classmethod
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def needs_update(cls, hash, **kwds):
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# NOTE: can't convert this to use _calc_needs_update() helper,
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# since _norm_hash() will correct salt padding before we can read it here.
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# check for incorrect padding bits (passlib issue 25)
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if isinstance(hash, bytes):
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hash = hash.decode("ascii")
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if hash.startswith(IDENT_2A) and hash[28] not in cls.final_salt_chars:
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return True
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# TODO: try to detect incorrect 8bit/wraparound hashes using kwds.get("secret")
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# hand off to base implementation, so HasRounds can check rounds value.
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return super(_BcryptCommon, cls).needs_update(hash, **kwds)
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#===================================================================
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# specialized salt generation - fixes passlib issue 25
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#===================================================================
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@classmethod
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def normhash(cls, hash):
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"""helper to normalize hash, correcting any bcrypt padding bits"""
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if cls.identify(hash):
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return cls.from_string(hash).to_string()
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else:
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return hash
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@classmethod
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def _generate_salt(cls):
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# generate random salt as normal,
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# but repair last char so the padding bits always decode to zero.
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salt = super(_BcryptCommon, cls)._generate_salt()
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return bcrypt64.repair_unused(salt)
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@classmethod
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def _norm_salt(cls, salt, **kwds):
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salt = super(_BcryptCommon, cls)._norm_salt(salt, **kwds)
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assert salt is not None, "HasSalt didn't generate new salt!"
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changed, salt = bcrypt64.check_repair_unused(salt)
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if changed:
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# FIXME: if salt was provided by user, this message won't be
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# correct. not sure if we want to throw error, or use different warning.
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warn(
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"encountered a bcrypt salt with incorrectly set padding bits; "
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"you may want to use bcrypt.normhash() "
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"to fix this; this will be an error under Passlib 2.0",
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PasslibHashWarning)
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return salt
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def _norm_checksum(self, checksum, relaxed=False):
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checksum = super(_BcryptCommon, self)._norm_checksum(checksum, relaxed=relaxed)
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changed, checksum = bcrypt64.check_repair_unused(checksum)
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if changed:
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warn(
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"encountered a bcrypt hash with incorrectly set padding bits; "
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"you may want to use bcrypt.normhash() "
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"to fix this; this will be an error under Passlib 2.0",
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PasslibHashWarning)
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return checksum
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#===================================================================
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# backend configuration
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# NOTE: backends are defined in terms of mixin classes,
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# which are dynamically inserted into the bases of the 'bcrypt' class
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# via the machinery in 'SubclassBackendMixin'.
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# this lets us load in a backend-specific implementation
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# of _calc_checksum() and similar methods.
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#===================================================================
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# NOTE: backend config is located down in <bcrypt> class
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# NOTE: set_backend() will execute the ._load_backend_mixin()
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# of the matching mixin class, which will handle backend detection
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# appended to HasManyBackends' "no backends available" error message
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_no_backend_suggestion = " -- recommend you install one (e.g. 'pip install bcrypt')"
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@classmethod
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def _finalize_backend_mixin(mixin_cls, backend, dryrun):
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"""
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helper called by from backend mixin classes' _load_backend_mixin() --
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invoked after backend imports have been loaded, and performs
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feature detection & testing common to all backends.
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"""
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#----------------------------------------------------------------
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# setup helpers
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#----------------------------------------------------------------
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assert mixin_cls is bcrypt._backend_mixin_map[backend], \
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"_configure_workarounds() invoked from wrong class"
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if mixin_cls._workrounds_initialized:
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return True
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verify = mixin_cls.verify
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err_types = (ValueError, uh.exc.MissingBackendError)
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if _bcryptor:
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err_types += (_bcryptor.engine.SaltError,)
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def safe_verify(secret, hash):
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"""verify() wrapper which traps 'unknown identifier' errors"""
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try:
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return verify(secret, hash)
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except err_types:
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# backends without support for given ident will throw various
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# errors about unrecognized version:
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# os_crypt -- internal code below throws
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# - PasswordValueError if there's encoding issue w/ password.
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# - InternalBackendError if crypt fails for unknown reason
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# (trapped below so we can debug it)
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# pybcrypt, bcrypt -- raises ValueError
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# bcryptor -- raises bcryptor.engine.SaltError
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return NotImplemented
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except uh.exc.InternalBackendError:
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# _calc_checksum() code may also throw CryptBackendError
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# if correct hash isn't returned (e.g. 2y hash converted to 2b,
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# such as happens with bcrypt 3.0.0)
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log.debug("trapped unexpected response from %r backend: verify(%r, %r):",
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backend, secret, hash, exc_info=True)
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return NotImplemented
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def assert_lacks_8bit_bug(ident):
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"""
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helper to check for cryptblowfish 8bit bug (fixed in 2y/2b);
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even though it's not known to be present in any of passlib's backends.
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this is treated as FATAL, because it can easily result in seriously malformed hashes,
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and we can't correct for it ourselves.
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test cases from <http://cvsweb.openwall.com/cgi/cvsweb.cgi/Owl/packages/glibc/crypt_blowfish/wrapper.c.diff?r1=1.9;r2=1.10>
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reference hash is the incorrectly generated $2x$ hash taken from above url
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"""
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# NOTE: passlib 1.7.2 and earlier used the commented-out LATIN-1 test vector to detect
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# this bug; but python3's crypt.crypt() only supports unicode inputs (and
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# always encodes them as UTF8 before passing to crypt); so passlib 1.7.3
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# switched to the UTF8-compatible test vector below. This one's bug_hash value
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# ("$2x$...rcAS") was drawn from the same openwall source (above); and the correct
|
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# hash ("$2a$...X6eu") was generated by passing the raw bytes to python2's
|
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# crypt.crypt() using OpenBSD 6.7 (hash confirmed as same for $2a$ & $2b$).
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# LATIN-1 test vector
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# secret = b"\xA3"
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# bug_hash = ident.encode("ascii") + b"05$/OK.fbVrR/bpIqNJ5ianF.CE5elHaaO4EbggVDjb8P19RukzXSM3e"
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# correct_hash = ident.encode("ascii") + b"05$/OK.fbVrR/bpIqNJ5ianF.Sa7shbm4.OzKpvFnX1pQLmQW96oUlCq"
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|
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# UTF-8 test vector
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secret = b"\xd1\x91" # aka "\u0451"
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bug_hash = ident.encode("ascii") + b"05$6bNw2HLQYeqHYyBfLMsv/OiwqTymGIGzFsA4hOTWebfehXHNprcAS"
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correct_hash = ident.encode("ascii") + b"05$6bNw2HLQYeqHYyBfLMsv/OUcZd0LKP39b87nBw3.S2tVZSqiQX6eu"
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if verify(secret, bug_hash):
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# NOTE: this only EVER be observed in (broken) 2a and (backward-compat) 2x hashes
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# generated by crypt_blowfish library. 2y/2b hashes should not have the bug
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# (but we check w/ them anyways).
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raise PasslibSecurityError(
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"passlib.hash.bcrypt: Your installation of the %r backend is vulnerable to "
|
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"the crypt_blowfish 8-bit bug (CVE-2011-2483) under %r hashes, "
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"and should be upgraded or replaced with another backend" % (backend, ident))
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# it doesn't have wraparound bug, but make sure it *does* verify against the correct
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# hash, or we're in some weird third case!
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if not verify(secret, correct_hash):
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raise RuntimeError("%s backend failed to verify %s 8bit hash" % (backend, ident))
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|
|
|
def detect_wrap_bug(ident):
|
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"""
|
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check for bsd wraparound bug (fixed in 2b)
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this is treated as a warning, because it's rare in the field,
|
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and pybcrypt (as of 2015-7-21) is unpatched, but some people may be stuck with it.
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test cases from <http://www.openwall.com/lists/oss-security/2012/01/02/4>
|
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NOTE: reference hash is of password "0"*72
|
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|
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NOTE: if in future we need to deliberately create hashes which have this bug,
|
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can use something like 'hashpw(repeat_string(secret[:((1+secret) % 256) or 1]), 72)'
|
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"""
|
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# check if it exhibits wraparound bug
|
|
secret = (b"0123456789"*26)[:255]
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bug_hash = ident.encode("ascii") + b"04$R1lJ2gkNaoPGdafE.H.16.nVyh2niHsGJhayOHLMiXlI45o8/DU.6"
|
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if verify(secret, bug_hash):
|
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return True
|
|
|
|
# if it doesn't have wraparound bug, make sure it *does* handle things
|
|
# correctly -- or we're in some weird third case.
|
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correct_hash = ident.encode("ascii") + b"04$R1lJ2gkNaoPGdafE.H.16.1MKHPvmKwryeulRe225LKProWYwt9Oi"
|
|
if not verify(secret, correct_hash):
|
|
raise RuntimeError("%s backend failed to verify %s wraparound hash" % (backend, ident))
|
|
|
|
return False
|
|
|
|
def assert_lacks_wrap_bug(ident):
|
|
if not detect_wrap_bug(ident):
|
|
return
|
|
# should only see in 2a, later idents should NEVER exhibit this bug:
|
|
# * 2y implementations should have been free of it
|
|
# * 2b was what (supposedly) fixed it
|
|
raise RuntimeError("%s backend unexpectedly has wraparound bug for %s" % (backend, ident))
|
|
|
|
#----------------------------------------------------------------
|
|
# check for old 20 support
|
|
#----------------------------------------------------------------
|
|
test_hash_20 = b"$2$04$5BJqKfqMQvV7nS.yUguNcuRfMMOXK0xPWavM7pOzjEi5ze5T1k8/S"
|
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result = safe_verify("test", test_hash_20)
|
|
if result is NotImplemented:
|
|
mixin_cls._lacks_20_support = True
|
|
log.debug("%r backend lacks $2$ support, enabling workaround", backend)
|
|
elif not result:
|
|
raise RuntimeError("%s incorrectly rejected $2$ hash" % backend)
|
|
|
|
#----------------------------------------------------------------
|
|
# check for 2a support
|
|
#----------------------------------------------------------------
|
|
result = safe_verify("test", TEST_HASH_2A)
|
|
if result is NotImplemented:
|
|
# 2a support is required, and should always be present
|
|
raise RuntimeError("%s lacks support for $2a$ hashes" % backend)
|
|
elif not result:
|
|
raise RuntimeError("%s incorrectly rejected $2a$ hash" % backend)
|
|
else:
|
|
assert_lacks_8bit_bug(IDENT_2A)
|
|
if detect_wrap_bug(IDENT_2A):
|
|
if backend == "os_crypt":
|
|
# don't make this a warning for os crypt (e.g. openbsd);
|
|
# they'll have proper 2b implementation which will be used for new hashes.
|
|
# so even if we didn't have a workaround, this bug wouldn't be a concern.
|
|
log.debug("%r backend has $2a$ bsd wraparound bug, enabling workaround", backend)
|
|
else:
|
|
# installed library has the bug -- want to let users know,
|
|
# so they can upgrade it to something better (e.g. bcrypt cffi library)
|
|
warn("passlib.hash.bcrypt: Your installation of the %r backend is vulnerable to "
|
|
"the bsd wraparound bug, "
|
|
"and should be upgraded or replaced with another backend "
|
|
"(enabling workaround for now)." % backend,
|
|
uh.exc.PasslibSecurityWarning)
|
|
mixin_cls._has_2a_wraparound_bug = True
|
|
|
|
#----------------------------------------------------------------
|
|
# check for 2y support
|
|
#----------------------------------------------------------------
|
|
test_hash_2y = TEST_HASH_2A.replace("2a", "2y")
|
|
result = safe_verify("test", test_hash_2y)
|
|
if result is NotImplemented:
|
|
mixin_cls._lacks_2y_support = True
|
|
log.debug("%r backend lacks $2y$ support, enabling workaround", backend)
|
|
elif not result:
|
|
raise RuntimeError("%s incorrectly rejected $2y$ hash" % backend)
|
|
else:
|
|
# NOTE: Not using this as fallback candidate,
|
|
# lacks wide enough support across implementations.
|
|
assert_lacks_8bit_bug(IDENT_2Y)
|
|
assert_lacks_wrap_bug(IDENT_2Y)
|
|
|
|
#----------------------------------------------------------------
|
|
# TODO: check for 2x support
|
|
#----------------------------------------------------------------
|
|
|
|
#----------------------------------------------------------------
|
|
# check for 2b support
|
|
#----------------------------------------------------------------
|
|
test_hash_2b = TEST_HASH_2A.replace("2a", "2b")
|
|
result = safe_verify("test", test_hash_2b)
|
|
if result is NotImplemented:
|
|
mixin_cls._lacks_2b_support = True
|
|
log.debug("%r backend lacks $2b$ support, enabling workaround", backend)
|
|
elif not result:
|
|
raise RuntimeError("%s incorrectly rejected $2b$ hash" % backend)
|
|
else:
|
|
mixin_cls._fallback_ident = IDENT_2B
|
|
assert_lacks_8bit_bug(IDENT_2B)
|
|
assert_lacks_wrap_bug(IDENT_2B)
|
|
|
|
# set flag so we don't have to run this again
|
|
mixin_cls._workrounds_initialized = True
|
|
return True
|
|
|
|
#===================================================================
|
|
# digest calculation
|
|
#===================================================================
|
|
|
|
# _calc_checksum() defined by backends
|
|
|
|
def _prepare_digest_args(self, secret):
|
|
"""
|
|
common helper for backends to implement _calc_checksum().
|
|
takes in secret, returns (secret, ident) pair,
|
|
"""
|
|
return self._norm_digest_args(secret, self.ident, new=self.use_defaults)
|
|
|
|
@classmethod
|
|
def _norm_digest_args(cls, secret, ident, new=False):
|
|
# make sure secret is unicode
|
|
require_valid_utf8_bytes = cls._require_valid_utf8_bytes
|
|
if isinstance(secret, unicode):
|
|
secret = secret.encode("utf-8")
|
|
elif require_valid_utf8_bytes:
|
|
# if backend requires utf8 bytes (os_crypt);
|
|
# make sure input actually is utf8, or don't bother enabling utf-8 specific helpers.
|
|
try:
|
|
secret.decode("utf-8")
|
|
except UnicodeDecodeError:
|
|
# XXX: could just throw PasswordValueError here, backend will just do that
|
|
# when _calc_digest() is actually called.
|
|
require_valid_utf8_bytes = False
|
|
|
|
# check max secret size
|
|
uh.validate_secret(secret)
|
|
|
|
# check for truncation (during .hash() calls only)
|
|
if new:
|
|
cls._check_truncate_policy(secret)
|
|
|
|
# NOTE: especially important to forbid NULLs for bcrypt, since many
|
|
# backends (bcryptor, bcrypt) happily accept them, and then
|
|
# silently truncate the password at first NULL they encounter!
|
|
if _BNULL in secret:
|
|
raise uh.exc.NullPasswordError(cls)
|
|
|
|
# TODO: figure out way to skip these tests when not needed...
|
|
|
|
# protect from wraparound bug by truncating secret before handing it to the backend.
|
|
# bcrypt only uses first 72 bytes anyways.
|
|
# NOTE: not needed for 2y/2b, but might use 2a as fallback for them.
|
|
if cls._has_2a_wraparound_bug and len(secret) >= 255:
|
|
if require_valid_utf8_bytes:
|
|
# backend requires valid utf8 bytes, so truncate secret to nearest valid segment.
|
|
# want to do this in constant time to not give away info about secret.
|
|
# NOTE: this only works because bcrypt will ignore everything past
|
|
# secret[71], so padding to include a full utf8 sequence
|
|
# won't break anything about the final output.
|
|
secret = utf8_truncate(secret, 72)
|
|
else:
|
|
secret = secret[:72]
|
|
|
|
# special case handling for variants (ordered most common first)
|
|
if ident == IDENT_2A:
|
|
# nothing needs to be done.
|
|
pass
|
|
|
|
elif ident == IDENT_2B:
|
|
if cls._lacks_2b_support:
|
|
# handle $2b$ hash format even if backend is too old.
|
|
# have it generate a 2A/2Y digest, then return it as a 2B hash.
|
|
# 2a-only backend could potentially exhibit wraparound bug --
|
|
# but we work around that issue above.
|
|
ident = cls._fallback_ident
|
|
|
|
elif ident == IDENT_2Y:
|
|
if cls._lacks_2y_support:
|
|
# handle $2y$ hash format (not supported by BSDs, being phased out on others)
|
|
# have it generate a 2A/2B digest, then return it as a 2Y hash.
|
|
ident = cls._fallback_ident
|
|
|
|
elif ident == IDENT_2:
|
|
if cls._lacks_20_support:
|
|
# handle legacy $2$ format (not supported by most backends except BSD os_crypt)
|
|
# we can fake $2$ behavior using the 2A/2Y/2B algorithm
|
|
# by repeating the password until it's at least 72 chars in length.
|
|
if secret:
|
|
if require_valid_utf8_bytes:
|
|
# NOTE: this only works because bcrypt will ignore everything past
|
|
# secret[71], so padding to include a full utf8 sequence
|
|
# won't break anything about the final output.
|
|
secret = utf8_repeat_string(secret, 72)
|
|
else:
|
|
secret = repeat_string(secret, 72)
|
|
ident = cls._fallback_ident
|
|
|
|
elif ident == IDENT_2X:
|
|
|
|
# NOTE: shouldn't get here.
|
|
# XXX: could check if backend does actually offer 'support'
|
|
raise RuntimeError("$2x$ hashes not currently supported by passlib")
|
|
|
|
else:
|
|
raise AssertionError("unexpected ident value: %r" % ident)
|
|
|
|
return secret, ident
|
|
|
|
#-----------------------------------------------------------------------
|
|
# stub backend
|
|
#-----------------------------------------------------------------------
|
|
class _NoBackend(_BcryptCommon):
|
|
"""
|
|
mixin used before any backend has been loaded.
|
|
contains stubs that force loading of one of the available backends.
|
|
"""
|
|
#===================================================================
|
|
# digest calculation
|
|
#===================================================================
|
|
def _calc_checksum(self, secret):
|
|
self._stub_requires_backend()
|
|
# NOTE: have to use super() here so that we don't recursively
|
|
# call subclass's wrapped _calc_checksum, e.g. bcrypt_sha256._calc_checksum
|
|
return super(bcrypt, self)._calc_checksum(secret)
|
|
|
|
#===================================================================
|
|
# eoc
|
|
#===================================================================
|
|
|
|
#-----------------------------------------------------------------------
|
|
# bcrypt backend
|
|
#-----------------------------------------------------------------------
|
|
class _BcryptBackend(_BcryptCommon):
|
|
"""
|
|
backend which uses 'bcrypt' package
|
|
"""
|
|
|
|
@classmethod
|
|
def _load_backend_mixin(mixin_cls, name, dryrun):
|
|
# try to import bcrypt
|
|
global _bcrypt
|
|
if _detect_pybcrypt():
|
|
# pybcrypt was installed instead
|
|
return False
|
|
try:
|
|
import bcrypt as _bcrypt
|
|
except ImportError: # pragma: no cover
|
|
return False
|
|
try:
|
|
version = _bcrypt.__about__.__version__
|
|
except:
|
|
log.warning("(trapped) error reading bcrypt version", exc_info=True)
|
|
version = '<unknown>'
|
|
|
|
log.debug("detected 'bcrypt' backend, version %r", version)
|
|
return mixin_cls._finalize_backend_mixin(name, dryrun)
|
|
|
|
# # TODO: would like to implementing verify() directly,
|
|
# # to skip need for parsing hash strings.
|
|
# # below method has a few edge cases where it chokes though.
|
|
# @classmethod
|
|
# def verify(cls, secret, hash):
|
|
# if isinstance(hash, unicode):
|
|
# hash = hash.encode("ascii")
|
|
# ident = hash[:hash.index(b"$", 1)+1].decode("ascii")
|
|
# if ident not in cls.ident_values:
|
|
# raise uh.exc.InvalidHashError(cls)
|
|
# secret, eff_ident = cls._norm_digest_args(secret, ident)
|
|
# if eff_ident != ident:
|
|
# # lacks support for original ident, replace w/ new one.
|
|
# hash = eff_ident.encode("ascii") + hash[len(ident):]
|
|
# result = _bcrypt.hashpw(secret, hash)
|
|
# assert result.startswith(eff_ident)
|
|
# return consteq(result, hash)
|
|
|
|
def _calc_checksum(self, secret):
|
|
# bcrypt behavior:
|
|
# secret must be bytes
|
|
# config must be ascii bytes
|
|
# returns ascii bytes
|
|
secret, ident = self._prepare_digest_args(secret)
|
|
config = self._get_config(ident)
|
|
if isinstance(config, unicode):
|
|
config = config.encode("ascii")
|
|
hash = _bcrypt.hashpw(secret, config)
|
|
assert isinstance(hash, bytes)
|
|
if not hash.startswith(config) or len(hash) != len(config)+31:
|
|
raise uh.exc.CryptBackendError(self, config, hash, source="`bcrypt` package")
|
|
return hash[-31:].decode("ascii")
|
|
|
|
#-----------------------------------------------------------------------
|
|
# bcryptor backend
|
|
#-----------------------------------------------------------------------
|
|
class _BcryptorBackend(_BcryptCommon):
|
|
"""
|
|
backend which uses 'bcryptor' package
|
|
"""
|
|
|
|
@classmethod
|
|
def _load_backend_mixin(mixin_cls, name, dryrun):
|
|
# try to import bcryptor
|
|
global _bcryptor
|
|
try:
|
|
import bcryptor as _bcryptor
|
|
except ImportError: # pragma: no cover
|
|
return False
|
|
|
|
# deprecated as of 1.7.2
|
|
if not dryrun:
|
|
warn("Support for `bcryptor` is deprecated, and will be removed in Passlib 1.8; "
|
|
"Please use `pip install bcrypt` instead", DeprecationWarning)
|
|
|
|
return mixin_cls._finalize_backend_mixin(name, dryrun)
|
|
|
|
def _calc_checksum(self, secret):
|
|
# bcryptor behavior:
|
|
# py2: unicode secret/hash encoded as ascii bytes before use,
|
|
# bytes taken as-is; returns ascii bytes.
|
|
# py3: not supported
|
|
secret, ident = self._prepare_digest_args(secret)
|
|
config = self._get_config(ident)
|
|
hash = _bcryptor.engine.Engine(False).hash_key(secret, config)
|
|
if not hash.startswith(config) or len(hash) != len(config) + 31:
|
|
raise uh.exc.CryptBackendError(self, config, hash, source="bcryptor library")
|
|
return str_to_uascii(hash[-31:])
|
|
|
|
#-----------------------------------------------------------------------
|
|
# pybcrypt backend
|
|
#-----------------------------------------------------------------------
|
|
class _PyBcryptBackend(_BcryptCommon):
|
|
"""
|
|
backend which uses 'pybcrypt' package
|
|
"""
|
|
|
|
#: classwide thread lock used for pybcrypt < 0.3
|
|
_calc_lock = None
|
|
|
|
@classmethod
|
|
def _load_backend_mixin(mixin_cls, name, dryrun):
|
|
# try to import pybcrypt
|
|
global _pybcrypt
|
|
if not _detect_pybcrypt():
|
|
# not installed, or bcrypt installed instead
|
|
return False
|
|
try:
|
|
import bcrypt as _pybcrypt
|
|
except ImportError: # pragma: no cover
|
|
# XXX: should we raise AssertionError here? (if get here, _detect_pybcrypt() is broken)
|
|
return False
|
|
|
|
# deprecated as of 1.7.2
|
|
if not dryrun:
|
|
warn("Support for `py-bcrypt` is deprecated, and will be removed in Passlib 1.8; "
|
|
"Please use `pip install bcrypt` instead", DeprecationWarning)
|
|
|
|
# determine pybcrypt version
|
|
try:
|
|
version = _pybcrypt._bcrypt.__version__
|
|
except:
|
|
log.warning("(trapped) error reading pybcrypt version", exc_info=True)
|
|
version = "<unknown>"
|
|
log.debug("detected 'pybcrypt' backend, version %r", version)
|
|
|
|
# return calc function based on version
|
|
vinfo = parse_version(version) or (0, 0)
|
|
if vinfo < (0, 3):
|
|
warn("py-bcrypt %s has a major security vulnerability, "
|
|
"you should upgrade to py-bcrypt 0.3 immediately."
|
|
% version, uh.exc.PasslibSecurityWarning)
|
|
if mixin_cls._calc_lock is None:
|
|
import threading
|
|
mixin_cls._calc_lock = threading.Lock()
|
|
mixin_cls._calc_checksum = get_unbound_method_function(mixin_cls._calc_checksum_threadsafe)
|
|
|
|
return mixin_cls._finalize_backend_mixin(name, dryrun)
|
|
|
|
def _calc_checksum_threadsafe(self, secret):
|
|
# as workaround for pybcrypt < 0.3's concurrency issue,
|
|
# we wrap everything in a thread lock. as long as bcrypt is only
|
|
# used through passlib, this should be safe.
|
|
with self._calc_lock:
|
|
return self._calc_checksum_raw(secret)
|
|
|
|
def _calc_checksum_raw(self, secret):
|
|
# py-bcrypt behavior:
|
|
# py2: unicode secret/hash encoded as ascii bytes before use,
|
|
# bytes taken as-is; returns ascii bytes.
|
|
# py3: unicode secret encoded as utf-8 bytes,
|
|
# hash encoded as ascii bytes, returns ascii unicode.
|
|
secret, ident = self._prepare_digest_args(secret)
|
|
config = self._get_config(ident)
|
|
hash = _pybcrypt.hashpw(secret, config)
|
|
if not hash.startswith(config) or len(hash) != len(config) + 31:
|
|
raise uh.exc.CryptBackendError(self, config, hash, source="pybcrypt library")
|
|
return str_to_uascii(hash[-31:])
|
|
|
|
_calc_checksum = _calc_checksum_raw
|
|
|
|
#-----------------------------------------------------------------------
|
|
# os crypt backend
|
|
#-----------------------------------------------------------------------
|
|
class _OsCryptBackend(_BcryptCommon):
|
|
"""
|
|
backend which uses :func:`crypt.crypt`
|
|
"""
|
|
|
|
#: set flag to ensure _prepare_digest_args() doesn't create invalid utf8 string
|
|
#: when truncating bytes.
|
|
_require_valid_utf8_bytes = not crypt_accepts_bytes
|
|
|
|
@classmethod
|
|
def _load_backend_mixin(mixin_cls, name, dryrun):
|
|
if not test_crypt("test", TEST_HASH_2A):
|
|
return False
|
|
return mixin_cls._finalize_backend_mixin(name, dryrun)
|
|
|
|
def _calc_checksum(self, secret):
|
|
#
|
|
# run secret through crypt.crypt().
|
|
# if everything goes right, we'll get back a properly formed bcrypt hash.
|
|
#
|
|
secret, ident = self._prepare_digest_args(secret)
|
|
config = self._get_config(ident)
|
|
hash = safe_crypt(secret, config)
|
|
if hash is not None:
|
|
if not hash.startswith(config) or len(hash) != len(config) + 31:
|
|
raise uh.exc.CryptBackendError(self, config, hash)
|
|
return hash[-31:]
|
|
|
|
#
|
|
# Check if this failed due to non-UTF8 bytes
|
|
# In detail: under py3, crypt.crypt() requires unicode inputs, which are then encoded to
|
|
# utf8 before passing them to os crypt() call. this is done according to the "s" format
|
|
# specifier for PyArg_ParseTuple (https://docs.python.org/3/c-api/arg.html).
|
|
# There appears no way to get around that to pass raw bytes; so we just throw error here
|
|
# to let user know they need to use another backend if they want raw bytes support.
|
|
#
|
|
# XXX: maybe just let safe_crypt() throw UnicodeDecodeError under passlib 2.0,
|
|
# and then catch it above? maybe have safe_crypt ALWAYS throw error
|
|
# instead of returning None? (would save re-detecting what went wrong)
|
|
# XXX: isn't secret ALWAYS bytes at this point?
|
|
#
|
|
if PY3 and isinstance(secret, bytes):
|
|
try:
|
|
secret.decode("utf-8")
|
|
except UnicodeDecodeError:
|
|
raise error_from(uh.exc.PasswordValueError(
|
|
"python3 crypt.crypt() ony supports bytes passwords using UTF8; "
|
|
"passlib recommends running `pip install bcrypt` for general bcrypt support.",
|
|
), None)
|
|
|
|
#
|
|
# else crypt() call failed for unknown reason.
|
|
#
|
|
# NOTE: getting here should be considered a bug in passlib --
|
|
# if os_crypt backend detection said there's support,
|
|
# and we've already checked all known reasons above;
|
|
# want them to file bug so we can figure out what happened.
|
|
# in the meantime, users can avoid this by installing bcrypt-cffi backend;
|
|
# which won't have this (or utf8) edgecases.
|
|
#
|
|
# XXX: throw something more specific, like an "InternalBackendError"?
|
|
# NOTE: if do change this error, need to update test_81_crypt_fallback() expectations
|
|
# about what will be thrown; as well as safe_verify() above.
|
|
#
|
|
debug_only_repr = uh.exc.debug_only_repr
|
|
raise uh.exc.InternalBackendError(
|
|
"crypt.crypt() failed for unknown reason; "
|
|
"passlib recommends running `pip install bcrypt` for general bcrypt support."
|
|
# for debugging UTs --
|
|
"(config=%s, secret=%s)" % (debug_only_repr(config), debug_only_repr(secret)),
|
|
)
|
|
|
|
#-----------------------------------------------------------------------
|
|
# builtin backend
|
|
#-----------------------------------------------------------------------
|
|
class _BuiltinBackend(_BcryptCommon):
|
|
"""
|
|
backend which uses passlib's pure-python implementation
|
|
"""
|
|
@classmethod
|
|
def _load_backend_mixin(mixin_cls, name, dryrun):
|
|
from passlib.utils import as_bool
|
|
if not as_bool(os.environ.get("PASSLIB_BUILTIN_BCRYPT")):
|
|
log.debug("bcrypt 'builtin' backend not enabled via $PASSLIB_BUILTIN_BCRYPT")
|
|
return False
|
|
global _builtin_bcrypt
|
|
from passlib.crypto._blowfish import raw_bcrypt as _builtin_bcrypt
|
|
return mixin_cls._finalize_backend_mixin(name, dryrun)
|
|
|
|
def _calc_checksum(self, secret):
|
|
secret, ident = self._prepare_digest_args(secret)
|
|
chk = _builtin_bcrypt(secret, ident[1:-1],
|
|
self.salt.encode("ascii"), self.rounds)
|
|
return chk.decode("ascii")
|
|
|
|
#=============================================================================
|
|
# handler
|
|
#=============================================================================
|
|
class bcrypt(_NoBackend, _BcryptCommon):
|
|
"""This class implements the BCrypt password hash, and follows the :ref:`password-hash-api`.
|
|
|
|
It supports a fixed-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 22 characters, drawn from the regexp range ``[./0-9A-Za-z]``.
|
|
|
|
:type rounds: int
|
|
:param rounds:
|
|
Optional number of rounds to use.
|
|
Defaults to 12, must be between 4 and 31, inclusive.
|
|
This value is logarithmic, the actual number of iterations used will be :samp:`2**{rounds}`
|
|
-- increasing the rounds by +1 will double the amount of time taken.
|
|
|
|
:type ident: str
|
|
:param ident:
|
|
Specifies which version of the BCrypt algorithm will be used when creating a new hash.
|
|
Typically this option is not needed, as the default (``"2b"``) is usually the correct choice.
|
|
If specified, it must be one of the following:
|
|
|
|
* ``"2"`` - the first revision of BCrypt, which suffers from a minor security flaw and is generally not used anymore.
|
|
* ``"2a"`` - some implementations suffered from rare security flaws, replaced by 2b.
|
|
* ``"2y"`` - format specific to the *crypt_blowfish* BCrypt implementation,
|
|
identical to ``"2b"`` in all but name.
|
|
* ``"2b"`` - latest revision of the official BCrypt algorithm, current default.
|
|
|
|
:param bool truncate_error:
|
|
By default, BCrypt will silently truncate passwords larger than 72 bytes.
|
|
Setting ``truncate_error=True`` will cause :meth:`~passlib.ifc.PasswordHash.hash`
|
|
to raise a :exc:`~passlib.exc.PasswordTruncateError` instead.
|
|
|
|
.. versionadded:: 1.7
|
|
|
|
: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
|
|
|
|
.. versionchanged:: 1.6
|
|
This class now supports ``"2y"`` hashes, and recognizes
|
|
(but does not support) the broken ``"2x"`` hashes.
|
|
(see the :ref:`crypt_blowfish bug <crypt-blowfish-bug>`
|
|
for details).
|
|
|
|
.. versionchanged:: 1.6
|
|
Added a pure-python backend.
|
|
|
|
.. versionchanged:: 1.6.3
|
|
|
|
Added support for ``"2b"`` variant.
|
|
|
|
.. versionchanged:: 1.7
|
|
|
|
Now defaults to ``"2b"`` variant.
|
|
"""
|
|
#=============================================================================
|
|
# backend
|
|
#=============================================================================
|
|
|
|
# NOTE: the brunt of the bcrypt class is implemented in _BcryptCommon.
|
|
# there are then subclass for each backend (e.g. _PyBcryptBackend),
|
|
# these are dynamically prepended to this class's bases
|
|
# in order to load the appropriate backend.
|
|
|
|
#: list of potential backends
|
|
backends = ("bcrypt", "pybcrypt", "bcryptor", "os_crypt", "builtin")
|
|
|
|
#: flag that this class's bases should be modified by SubclassBackendMixin
|
|
_backend_mixin_target = True
|
|
|
|
#: map of backend -> mixin class, used by _get_backend_loader()
|
|
_backend_mixin_map = {
|
|
None: _NoBackend,
|
|
"bcrypt": _BcryptBackend,
|
|
"pybcrypt": _PyBcryptBackend,
|
|
"bcryptor": _BcryptorBackend,
|
|
"os_crypt": _OsCryptBackend,
|
|
"builtin": _BuiltinBackend,
|
|
}
|
|
|
|
#=============================================================================
|
|
# eoc
|
|
#=============================================================================
|
|
|
|
#=============================================================================
|
|
# variants
|
|
#=============================================================================
|
|
_UDOLLAR = u("$")
|
|
|
|
# XXX: it might be better to have all the bcrypt variants share a common base class,
|
|
# and have the (django_)bcrypt_sha256 wrappers just proxy bcrypt instead of subclassing it.
|
|
class _wrapped_bcrypt(bcrypt):
|
|
"""
|
|
abstracts out some bits bcrypt_sha256 & django_bcrypt_sha256 share.
|
|
- bypass backend-loading wrappers for hash() etc
|
|
- disable truncation support, sha256 wrappers don't need it.
|
|
"""
|
|
setting_kwds = tuple(elem for elem in bcrypt.setting_kwds if elem not in ["truncate_error"])
|
|
truncate_size = None
|
|
|
|
# XXX: these will be needed if any bcrypt backends directly implement this...
|
|
# @classmethod
|
|
# def hash(cls, secret, **kwds):
|
|
# # bypass bcrypt backend overriding this method
|
|
# # XXX: would wrapping bcrypt make this easier than subclassing it?
|
|
# return super(_BcryptCommon, cls).hash(secret, **kwds)
|
|
#
|
|
# @classmethod
|
|
# def verify(cls, secret, hash):
|
|
# # bypass bcrypt backend overriding this method
|
|
# return super(_BcryptCommon, cls).verify(secret, hash)
|
|
#
|
|
# @classmethod
|
|
# def genhash(cls, secret, hash):
|
|
# # bypass bcrypt backend overriding this method
|
|
# return super(_BcryptCommon, cls).genhash(secret, hash)
|
|
|
|
@classmethod
|
|
def _check_truncate_policy(cls, secret):
|
|
# disable check performed by bcrypt(), since this doesn't truncate passwords.
|
|
pass
|
|
|
|
#=============================================================================
|
|
# bcrypt sha256 wrapper
|
|
#=============================================================================
|
|
|
|
class bcrypt_sha256(_wrapped_bcrypt):
|
|
"""
|
|
This class implements a composition of BCrypt + HMAC_SHA256,
|
|
and follows the :ref:`password-hash-api`.
|
|
|
|
It supports a fixed-length salt, and a variable number of rounds.
|
|
|
|
The :meth:`~passlib.ifc.PasswordHash.hash` and :meth:`~passlib.ifc.PasswordHash.genconfig` methods accept
|
|
all the same optional keywords as the base :class:`bcrypt` hash.
|
|
|
|
.. versionadded:: 1.6.2
|
|
|
|
.. versionchanged:: 1.7
|
|
|
|
Now defaults to ``"2b"`` bcrypt variant; though supports older hashes
|
|
generated using the ``"2a"`` bcrypt variant.
|
|
|
|
.. versionchanged:: 1.7.3
|
|
|
|
For increased security, updated to use HMAC-SHA256 instead of plain SHA256.
|
|
Now only supports the ``"2b"`` bcrypt variant. Hash format updated to "v=2".
|
|
"""
|
|
#===================================================================
|
|
# class attrs
|
|
#===================================================================
|
|
|
|
#--------------------
|
|
# PasswordHash
|
|
#--------------------
|
|
name = "bcrypt_sha256"
|
|
|
|
#--------------------
|
|
# GenericHandler
|
|
#--------------------
|
|
# this is locked at 2b for now (with 2a allowed only for legacy v1 format)
|
|
ident_values = (IDENT_2A, IDENT_2B)
|
|
|
|
# clone bcrypt's ident aliases so they can be used here as well...
|
|
ident_aliases = (lambda ident_values: dict(item for item in bcrypt.ident_aliases.items()
|
|
if item[1] in ident_values))(ident_values)
|
|
default_ident = IDENT_2B
|
|
|
|
#--------------------
|
|
# class specific
|
|
#--------------------
|
|
|
|
_supported_versions = set([1, 2])
|
|
|
|
#===================================================================
|
|
# instance attrs
|
|
#===================================================================
|
|
|
|
#: wrapper version.
|
|
#: v1 -- used prior to passlib 1.7.3; performs ``bcrypt(sha256(secret), salt, cost)``
|
|
#: v2 -- new in passlib 1.7.3; performs `bcrypt(sha256_hmac(salt, secret), salt, cost)``
|
|
version = 2
|
|
|
|
#===================================================================
|
|
# configuration
|
|
#===================================================================
|
|
|
|
@classmethod
|
|
def using(cls, version=None, **kwds):
|
|
subcls = super(bcrypt_sha256, cls).using(**kwds)
|
|
if version is not None:
|
|
subcls.version = subcls._norm_version(version)
|
|
ident = subcls.default_ident
|
|
if subcls.version > 1 and ident != IDENT_2B:
|
|
raise ValueError("bcrypt %r hashes not allowed for version %r" %
|
|
(ident, subcls.version))
|
|
return subcls
|
|
|
|
#===================================================================
|
|
# formatting
|
|
#===================================================================
|
|
|
|
# sample hash:
|
|
# $bcrypt-sha256$2a,6$/3OeRpbOf8/l6nPPRdZPp.$nRiyYqPobEZGdNRBWihQhiFDh1ws1tu
|
|
# $bcrypt-sha256$ -- prefix/identifier
|
|
# 2a -- bcrypt variant
|
|
# , -- field separator
|
|
# 6 -- bcrypt work factor
|
|
# $ -- section separator
|
|
# /3OeRpbOf8/l6nPPRdZPp. -- salt
|
|
# $ -- section separator
|
|
# nRiyYqPobEZGdNRBWihQhiFDh1ws1tu -- digest
|
|
|
|
# XXX: we can't use .ident attr due to bcrypt code using it.
|
|
# working around that via prefix.
|
|
prefix = u('$bcrypt-sha256$')
|
|
|
|
#: current version 2 hash format
|
|
_v2_hash_re = re.compile(r"""(?x)
|
|
^
|
|
[$]bcrypt-sha256[$]
|
|
v=(?P<version>\d+),
|
|
t=(?P<type>2b),
|
|
r=(?P<rounds>\d{1,2})
|
|
[$](?P<salt>[^$]{22})
|
|
(?:[$](?P<digest>[^$]{31}))?
|
|
$
|
|
""")
|
|
|
|
#: old version 1 hash format
|
|
_v1_hash_re = re.compile(r"""(?x)
|
|
^
|
|
[$]bcrypt-sha256[$]
|
|
(?P<type>2[ab]),
|
|
(?P<rounds>\d{1,2})
|
|
[$](?P<salt>[^$]{22})
|
|
(?:[$](?P<digest>[^$]{31}))?
|
|
$
|
|
""")
|
|
|
|
@classmethod
|
|
def identify(cls, hash):
|
|
hash = uh.to_unicode_for_identify(hash)
|
|
if not hash:
|
|
return False
|
|
return hash.startswith(cls.prefix)
|
|
|
|
@classmethod
|
|
def from_string(cls, hash):
|
|
hash = to_unicode(hash, "ascii", "hash")
|
|
if not hash.startswith(cls.prefix):
|
|
raise uh.exc.InvalidHashError(cls)
|
|
m = cls._v2_hash_re.match(hash)
|
|
if m:
|
|
version = int(m.group("version"))
|
|
if version < 2:
|
|
raise uh.exc.MalformedHashError(cls)
|
|
else:
|
|
m = cls._v1_hash_re.match(hash)
|
|
if m:
|
|
version = 1
|
|
else:
|
|
raise uh.exc.MalformedHashError(cls)
|
|
rounds = m.group("rounds")
|
|
if rounds.startswith(uh._UZERO) and rounds != uh._UZERO:
|
|
raise uh.exc.ZeroPaddedRoundsError(cls)
|
|
return cls(
|
|
version=version,
|
|
ident=m.group("type"),
|
|
rounds=int(rounds),
|
|
salt=m.group("salt"),
|
|
checksum=m.group("digest"),
|
|
)
|
|
|
|
_v2_template = u("$bcrypt-sha256$v=2,t=%s,r=%d$%s$%s")
|
|
_v1_template = u("$bcrypt-sha256$%s,%d$%s$%s")
|
|
|
|
def to_string(self):
|
|
if self.version == 1:
|
|
template = self._v1_template
|
|
else:
|
|
template = self._v2_template
|
|
hash = template % (self.ident.strip(_UDOLLAR), self.rounds, self.salt, self.checksum)
|
|
return uascii_to_str(hash)
|
|
|
|
#===================================================================
|
|
# init
|
|
#===================================================================
|
|
|
|
def __init__(self, version=None, **kwds):
|
|
if version is not None:
|
|
self.version = self._norm_version(version)
|
|
super(bcrypt_sha256, self).__init__(**kwds)
|
|
|
|
#===================================================================
|
|
# version
|
|
#===================================================================
|
|
|
|
@classmethod
|
|
def _norm_version(cls, version):
|
|
if version not in cls._supported_versions:
|
|
raise ValueError("%s: unknown or unsupported version: %r" % (cls.name, version))
|
|
return version
|
|
|
|
#===================================================================
|
|
# checksum
|
|
#===================================================================
|
|
|
|
def _calc_checksum(self, secret):
|
|
# NOTE: can't use digest directly, since bcrypt stops at first NULL.
|
|
# NOTE: bcrypt doesn't fully mix entropy for bytes 55-72 of password
|
|
# (XXX: citation needed), so we don't want key to be > 55 bytes.
|
|
# thus, have to use base64 (44 bytes) rather than hex (64 bytes).
|
|
# XXX: it's later come out that 55-72 may be ok, so later revision of bcrypt_sha256
|
|
# may switch to hex encoding, since it's simpler to implement elsewhere.
|
|
if isinstance(secret, unicode):
|
|
secret = secret.encode("utf-8")
|
|
|
|
if self.version == 1:
|
|
# version 1 -- old version just ran secret through sha256(),
|
|
# though this could be vulnerable to a breach attach
|
|
# (c.f. issue 114); which is why v2 switched to hmac wrapper.
|
|
digest = sha256(secret).digest()
|
|
else:
|
|
# version 2 -- running secret through HMAC keyed off salt.
|
|
# this prevents known secret -> sha256 password tables from being
|
|
# used to test against a bcrypt_sha256 hash.
|
|
# keying off salt (instead of constant string) should minimize chances of this
|
|
# colliding with existing table of hmac digest lookups as well.
|
|
# NOTE: salt in this case is the "bcrypt64"-encoded value, not the raw salt bytes,
|
|
# to make things easier for parallel implementations of this hash --
|
|
# saving them the trouble of implementing a "bcrypt64" decoder.
|
|
salt = self.salt
|
|
if salt[-1] not in self.final_salt_chars:
|
|
# forbidding salts with padding bits set, because bcrypt implementations
|
|
# won't consistently hash them the same. since we control this format,
|
|
# just prevent these from even getting used.
|
|
raise ValueError("invalid salt string")
|
|
digest = compile_hmac("sha256", salt.encode("ascii"))(secret)
|
|
|
|
# NOTE: output of b64encode() uses "+/" altchars, "=" padding chars,
|
|
# and no leading/trailing whitespace.
|
|
key = b64encode(digest)
|
|
|
|
# hand result off to normal bcrypt algorithm
|
|
return super(bcrypt_sha256, self)._calc_checksum(key)
|
|
|
|
#===================================================================
|
|
# other
|
|
#===================================================================
|
|
|
|
def _calc_needs_update(self, **kwds):
|
|
if self.version < type(self).version:
|
|
return True
|
|
return super(bcrypt_sha256, self)._calc_needs_update(**kwds)
|
|
|
|
#===================================================================
|
|
# eoc
|
|
#===================================================================
|
|
|
|
#=============================================================================
|
|
# eof
|
|
#=============================================================================
|