Gestionnaire de fichiers - Editer - /usr/lib/python2.7/site-packages/passlib/crypto/digest.py
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"""passlib.crypto.digest -- crytographic helpers used by the password hashes in passlib .. versionadded:: 1.7 """ #============================================================================= # imports #============================================================================= from __future__ import division # core import hashlib import logging; log = logging.getLogger(__name__) try: # new in py3.4 from hashlib import pbkdf2_hmac as _stdlib_pbkdf2_hmac if _stdlib_pbkdf2_hmac.__module__ == "hashlib": # builtin pure-python backends are slightly faster than stdlib's pure python fallback, # so only using stdlib's version if it's backed by openssl's pbkdf2_hmac() log.debug("ignoring pure-python hashlib.pbkdf2_hmac()") _stdlib_pbkdf2_hmac = None except ImportError: _stdlib_pbkdf2_hmac = None import re import os from struct import Struct from warnings import warn # site try: # https://pypi.python.org/pypi/fastpbkdf2/ from fastpbkdf2 import pbkdf2_hmac as _fast_pbkdf2_hmac except ImportError: _fast_pbkdf2_hmac = None # pkg from passlib import exc from passlib.utils import join_bytes, to_native_str, join_byte_values, to_bytes, \ SequenceMixin from passlib.utils.compat import irange, int_types, unicode_or_bytes_types, PY3 from passlib.utils.decor import memoized_property # local __all__ = [ # hash utils "lookup_hash", "HashInfo", "norm_hash_name", # hmac utils "compile_hmac", # kdfs "pbkdf1", "pbkdf2_hmac", ] #============================================================================= # generic constants #============================================================================= #: max 32-bit value MAX_UINT32 = (1 << 32) - 1 #: max 64-bit value MAX_UINT64 = (1 << 64) - 1 #============================================================================= # hash utils #============================================================================= #: list of known hash names, used by lookup_hash()'s _norm_hash_name() helper _known_hash_names = [ # format: (hashlib/ssl name, iana name or standin, other known aliases ...) # hashes with official IANA-assigned names # (as of 2012-03 - http://www.iana.org/assignments/hash-function-text-names) ("md2", "md2"), ("md5", "md5"), ("sha1", "sha-1"), ("sha224", "sha-224", "sha2-224"), ("sha256", "sha-256", "sha2-256"), ("sha384", "sha-384", "sha2-384"), ("sha512", "sha-512", "sha2-512"), # TODO: add sha3 to this table. # hashlib/ssl-supported hashes without official IANA names, # (hopefully-) compatible stand-ins have been chosen. ("md4", "md4"), ("sha", "sha-0", "sha0"), ("ripemd", "ripemd"), ("ripemd160", "ripemd-160"), ] #: cache of hash info instances used by lookup_hash() _hash_info_cache = {} def _get_hash_aliases(name): """ internal helper used by :func:`lookup_hash` -- normalize arbitrary hash name to hashlib format. if name not recognized, returns dummy record and issues a warning. :arg name: unnormalized name :returns: tuple with 2+ elements: ``(hashlib_name, iana_name|None, ... 0+ aliases)``. """ # normalize input orig = name if not isinstance(name, str): name = to_native_str(name, 'utf-8', 'hash name') name = re.sub("[_ /]", "-", name.strip().lower()) if name.startswith("scram-"): # helper for SCRAM protocol (see passlib.handlers.scram) name = name[6:] if name.endswith("-plus"): name = name[:-5] # look through standard names and known aliases def check_table(name): for row in _known_hash_names: if name in row: return row result = check_table(name) if result: return result # try to clean name up some more m = re.match(r"(?i)^(?P<name>[a-z]+)-?(?P<rev>\d)?-?(?P<size>\d{3,4})?$", name) if m: # roughly follows "SHA2-256" style format, normalize representation, # and checked table. iana_name, rev, size = m.group("name", "rev", "size") if rev: iana_name += rev hashlib_name = iana_name if size: iana_name += "-" + size if rev: hashlib_name += "_" hashlib_name += size result = check_table(iana_name) if result: return result # not found in table, but roughly recognize format. use names we built up as fallback. log.info("normalizing unrecognized hash name %r => %r / %r", orig, hashlib_name, iana_name) else: # just can't make sense of it. return something iana_name = name hashlib_name = name.replace("-", "_") log.warning("normalizing unrecognized hash name and format %r => %r / %r", orig, hashlib_name, iana_name) return hashlib_name, iana_name def _get_hash_const(name): """ internal helper used by :func:`lookup_hash` -- lookup hash constructor by name :arg name: name (normalized to hashlib format, e.g. ``"sha256"``) :returns: hash constructor, e.g. ``hashlib.sha256()``; or None if hash can't be located. """ # check hashlib.<attr> for an efficient constructor if not name.startswith("_") and name not in ("new", "algorithms"): try: return getattr(hashlib, name) except AttributeError: pass # check hashlib.new() in case SSL supports the digest new_ssl_hash = hashlib.new try: # new() should throw ValueError if alg is unknown new_ssl_hash(name, b"") except ValueError: pass else: # create wrapper function # XXX: is there a faster way to wrap this? def const(msg=b""): return new_ssl_hash(name, msg) const.__name__ = name const.__module__ = "hashlib" const.__doc__ = ("wrapper for hashlib.new(%r),\n" "generated by passlib.crypto.digest.lookup_hash()") % name return const # use builtin md4 as fallback when not supported by hashlib if name == "md4": from passlib.crypto._md4 import md4 return md4 # XXX: any other modules / registries we should check? # TODO: add pysha3 support. return None def lookup_hash(digest, return_unknown=False): """ Returns a :class:`HashInfo` record containing information about a given hash function. Can be used to look up a hash constructor by name, normalize hash name representation, etc. :arg digest: This can be any of: * A string containing a :mod:`!hashlib` digest name (e.g. ``"sha256"``), * A string containing an IANA-assigned hash name, * A digest constructor function (e.g. ``hashlib.sha256``). Case is ignored, underscores are converted to hyphens, and various other cleanups are made. :param return_unknown: By default, this function will throw an :exc:`~passlib.exc.UnknownHashError` if no hash constructor can be found. However, if this flag is False, it will instead return a dummy record without a constructor function. This is mainly used by :func:`norm_hash_name`. :returns HashInfo: :class:`HashInfo` instance containing information about specified digest. Multiple calls resolving to the same hash should always return the same :class:`!HashInfo` instance. """ # check for cached entry cache = _hash_info_cache try: return cache[digest] except (KeyError, TypeError): # NOTE: TypeError is to catch 'TypeError: unhashable type' (e.g. HashInfo) pass # resolve ``digest`` to ``const`` & ``name_record`` cache_by_name = True if isinstance(digest, unicode_or_bytes_types): # normalize name name_list = _get_hash_aliases(digest) name = name_list[0] assert name # if name wasn't normalized to hashlib format, # get info for normalized name and reuse it. if name != digest: info = lookup_hash(name, return_unknown=return_unknown) if info.const is None: # pass through dummy record assert return_unknown return info cache[digest] = info return info # else look up constructor const = _get_hash_const(name) if const is None: if return_unknown: # return a dummy record (but don't cache it, so normal lookup still returns error) return HashInfo(None, name_list) else: raise exc.UnknownHashError(name) elif isinstance(digest, HashInfo): # handle border case where HashInfo is passed in. return digest elif callable(digest): # try to lookup digest based on it's self-reported name # (which we trust to be the canonical "hashlib" name) const = digest name_list = _get_hash_aliases(const().name) name = name_list[0] other_const = _get_hash_const(name) if other_const is None: # this is probably a third-party digest we don't know about, # so just pass it on through, and register reverse lookup for it's name. pass elif other_const is const: # if we got back same constructor, this is just a known stdlib constructor, # which was passed in before we had cached it by name. proceed normally. pass else: # if we got back different object, then ``const`` is something else # (such as a mock object), in which case we want to skip caching it by name, # as that would conflict with real hash. cache_by_name = False else: raise exc.ExpectedTypeError(digest, "digest name or constructor", "digest") # create new instance info = HashInfo(const, name_list) # populate cache cache[const] = info if cache_by_name: for name in name_list: if name: # (skips iana name if it's empty) assert cache.get(name) in [None, info], "%r already in cache" % name cache[name] = info return info #: UT helper for clearing internal cache lookup_hash.clear_cache = _hash_info_cache.clear def norm_hash_name(name, format="hashlib"): """Normalize hash function name (convenience wrapper for :func:`lookup_hash`). :arg name: Original hash function name. This name can be a Python :mod:`~hashlib` digest name, a SCRAM mechanism name, IANA assigned hash name, etc. Case is ignored, and underscores are converted to hyphens. :param format: Naming convention to normalize to. Possible values are: * ``"hashlib"`` (the default) - normalizes name to be compatible with Python's :mod:`!hashlib`. * ``"iana"`` - normalizes name to IANA-assigned hash function name. For hashes which IANA hasn't assigned a name for, this issues a warning, and then uses a heuristic to return a "best guess" name. :returns: Hash name, returned as native :class:`!str`. """ info = lookup_hash(name, return_unknown=True) if not info.const: warn("norm_hash_name(): unknown hash: %r" % (name,), exc.PasslibRuntimeWarning) if format == "hashlib": return info.name elif format == "iana": return info.iana_name else: raise ValueError("unknown format: %r" % (format,)) class HashInfo(SequenceMixin): """ Record containing information about a given hash algorithm, as returned :func:`lookup_hash`. This class exposes the following attributes: .. autoattribute:: const .. autoattribute:: digest_size .. autoattribute:: block_size .. autoattribute:: name .. autoattribute:: iana_name .. autoattribute:: aliases This object can also be treated a 3-element sequence containing ``(const, digest_size, block_size)``. """ #========================================================================= # instance attrs #========================================================================= #: Canonical / hashlib-compatible name (e.g. ``"sha256"``). name = None #: IANA assigned name (e.g. ``"sha-256"``), may be ``None`` if unknown. iana_name = None #: Tuple of other known aliases (may be empty) aliases = () #: Hash constructor function (e.g. :func:`hashlib.sha256`) const = None #: Hash's digest size digest_size = None #: Hash's block size block_size = None def __init__(self, const, names): """ initialize new instance. :arg const: hash constructor :arg names: list of 2+ names. should be list of ``(name, iana_name, ... 0+ aliases)``. names must be lower-case. only iana name may be None. """ self.name = names[0] self.iana_name = names[1] self.aliases = names[2:] self.const = const if const is None: return hash = const() self.digest_size = hash.digest_size self.block_size = hash.block_size # do sanity check on digest size if len(hash.digest()) != hash.digest_size: raise RuntimeError("%r constructor failed sanity check" % self.name) # do sanity check on name. if hash.name != self.name: warn("inconsistent digest name: %r resolved to %r, which reports name as %r" % (self.name, const, hash.name), exc.PasslibRuntimeWarning) #========================================================================= # methods #========================================================================= def __repr__(self): return "<lookup_hash(%r): digest_size=%r block_size=%r)" % \ (self.name, self.digest_size, self.block_size) def _as_tuple(self): return self.const, self.digest_size, self.block_size @memoized_property def supported_by_fastpbkdf2(self): """helper to detect if hash is supported by fastpbkdf2()""" if not _fast_pbkdf2_hmac: return None try: _fast_pbkdf2_hmac(self.name, b"p", b"s", 1) return True except ValueError: # "unsupported hash type" return False @memoized_property def supported_by_hashlib_pbkdf2(self): """helper to detect if hash is supported by hashlib.pbkdf2_hmac()""" if not _stdlib_pbkdf2_hmac: return None try: _stdlib_pbkdf2_hmac(self.name, b"p", b"s", 1) return True except ValueError: # "unsupported hash type" return False #========================================================================= # eoc #========================================================================= #============================================================================= # hmac utils #============================================================================= #: translation tables used by compile_hmac() _TRANS_5C = join_byte_values((x ^ 0x5C) for x in irange(256)) _TRANS_36 = join_byte_values((x ^ 0x36) for x in irange(256)) def compile_hmac(digest, key, multipart=False): """ This function returns an efficient HMAC function, hardcoded with a specific digest & key. It can be used via ``hmac = compile_hmac(digest, key)``. :arg digest: digest name or constructor. :arg key: secret key as :class:`!bytes` or :class:`!unicode` (unicode will be encoded using utf-8). :param multipart: request a multipart constructor instead (see return description). :returns: By default, the returned function has the signature ``hmac(msg) -> digest output``. However, if ``multipart=True``, the returned function has the signature ``hmac() -> update, finalize``, where ``update(msg)`` may be called multiple times, and ``finalize() -> digest_output`` may be repeatedly called at any point to calculate the HMAC digest so far. The returned object will also have a ``digest_info`` attribute, containing a :class:`lookup_hash` instance for the specified digest. This function exists, and has the weird signature it does, in order to squeeze as provide as much efficiency as possible, by omitting much of the setup cost and features of the stdlib :mod:`hmac` module. """ # all the following was adapted from stdlib's hmac module # resolve digest (cached) digest_info = lookup_hash(digest) const, digest_size, block_size = digest_info assert block_size >= 16, "block size too small" # prepare key if not isinstance(key, bytes): key = to_bytes(key, param="key") klen = len(key) if klen > block_size: key = const(key).digest() klen = digest_size if klen < block_size: key += b'\x00' * (block_size - klen) # create pre-initialized hash constructors _inner_copy = const(key.translate(_TRANS_36)).copy _outer_copy = const(key.translate(_TRANS_5C)).copy if multipart: # create multi-part function # NOTE: this is slightly slower than the single-shot version, # and should only be used if needed. def hmac(): """generated by compile_hmac(multipart=True)""" inner = _inner_copy() def finalize(): outer = _outer_copy() outer.update(inner.digest()) return outer.digest() return inner.update, finalize else: # single-shot function def hmac(msg): """generated by compile_hmac()""" inner = _inner_copy() inner.update(msg) outer = _outer_copy() outer.update(inner.digest()) return outer.digest() # add info attr hmac.digest_info = digest_info return hmac #============================================================================= # pbkdf1 #============================================================================= def pbkdf1(digest, secret, salt, rounds, keylen=None): """pkcs#5 password-based key derivation v1.5 :arg digest: digest name or constructor. :arg secret: secret to use when generating the key. may be :class:`!bytes` or :class:`unicode` (encoded using UTF-8). :arg salt: salt string to use when generating key. may be :class:`!bytes` or :class:`unicode` (encoded using UTF-8). :param rounds: number of rounds to use to generate key. :arg keylen: number of bytes to generate (if omitted / ``None``, uses digest's native size) :returns: raw :class:`bytes` of generated key .. note:: This algorithm has been deprecated, new code should use PBKDF2. Among other limitations, ``keylen`` cannot be larger than the digest size of the specified hash. """ # resolve digest const, digest_size, block_size = lookup_hash(digest) # validate secret & salt secret = to_bytes(secret, param="secret") salt = to_bytes(salt, param="salt") # validate rounds if not isinstance(rounds, int_types): raise exc.ExpectedTypeError(rounds, "int", "rounds") if rounds < 1: raise ValueError("rounds must be at least 1") # validate keylen if keylen is None: keylen = digest_size elif not isinstance(keylen, int_types): raise exc.ExpectedTypeError(keylen, "int or None", "keylen") elif keylen < 0: raise ValueError("keylen must be at least 0") elif keylen > digest_size: raise ValueError("keylength too large for digest: %r > %r" % (keylen, digest_size)) # main pbkdf1 loop block = secret + salt for _ in irange(rounds): block = const(block).digest() return block[:keylen] #============================================================================= # pbkdf2 #============================================================================= _pack_uint32 = Struct(">L").pack def pbkdf2_hmac(digest, secret, salt, rounds, keylen=None): """pkcs#5 password-based key derivation v2.0 using HMAC + arbitrary digest. :arg digest: digest name or constructor. :arg secret: passphrase to use to generate key. may be :class:`!bytes` or :class:`unicode` (encoded using UTF-8). :arg salt: salt string to use when generating key. may be :class:`!bytes` or :class:`unicode` (encoded using UTF-8). :param rounds: number of rounds to use to generate key. :arg keylen: number of bytes to generate. if omitted / ``None``, will use digest's native output size. :returns: raw bytes of generated key .. versionchanged:: 1.7 This function will use the first available of the following backends: * `fastpbk2 <https://pypi.python.org/pypi/fastpbkdf2>`_ * :func:`hashlib.pbkdf2_hmac` (only available in py2 >= 2.7.8, and py3 >= 3.4) * builtin pure-python backend See :data:`passlib.crypto.digest.PBKDF2_BACKENDS` to determine which backend(s) are in use. """ # validate secret & salt secret = to_bytes(secret, param="secret") salt = to_bytes(salt, param="salt") # resolve digest digest_info = lookup_hash(digest) digest_size = digest_info.digest_size # validate rounds if not isinstance(rounds, int_types): raise exc.ExpectedTypeError(rounds, "int", "rounds") if rounds < 1: raise ValueError("rounds must be at least 1") # validate keylen if keylen is None: keylen = digest_size elif not isinstance(keylen, int_types): raise exc.ExpectedTypeError(keylen, "int or None", "keylen") elif keylen < 1: # XXX: could allow keylen=0, but want to be compat w/ stdlib raise ValueError("keylen must be at least 1") # find smallest block count s.t. keylen <= block_count * digest_size; # make sure block count won't overflow (per pbkdf2 spec) # this corresponds to throwing error if keylen > digest_size * MAX_UINT32 # NOTE: stdlib will throw error at lower bound (keylen > MAX_SINT32) # NOTE: have do this before other backends checked, since fastpbkdf2 raises wrong error # (InvocationError, not OverflowError) block_count = (keylen + digest_size - 1) // digest_size if block_count > MAX_UINT32: raise OverflowError("keylen too long for digest") # # check for various high-speed backends # # ~3x faster than pure-python backend # NOTE: have to do this after above guards since fastpbkdf2 lacks bounds checks. if digest_info.supported_by_fastpbkdf2: return _fast_pbkdf2_hmac(digest_info.name, secret, salt, rounds, keylen) # ~1.4x faster than pure-python backend # NOTE: have to do this after fastpbkdf2 since hashlib-ssl is slower, # will support larger number of hashes. if digest_info.supported_by_hashlib_pbkdf2: return _stdlib_pbkdf2_hmac(digest_info.name, secret, salt, rounds, keylen) # # otherwise use our own implementation # # generated keyed hmac keyed_hmac = compile_hmac(digest, secret) # get helper to calculate pbkdf2 inner loop efficiently calc_block = _get_pbkdf2_looper(digest_size) # assemble & return result return join_bytes( calc_block(keyed_hmac, keyed_hmac(salt + _pack_uint32(i)), rounds) for i in irange(1, block_count + 1) )[:keylen] #------------------------------------------------------------------------------------- # pick best choice for pure-python helper # TODO: consider some alternatives, such as C-accelerated xor_bytes helper if available #------------------------------------------------------------------------------------- # NOTE: this env var is only present to support the admin/benchmark_pbkdf2 script _force_backend = os.environ.get("PASSLIB_PBKDF2_BACKEND") or "any" if PY3 and _force_backend in ["any", "from-bytes"]: from functools import partial def _get_pbkdf2_looper(digest_size): return partial(_pbkdf2_looper, digest_size) def _pbkdf2_looper(digest_size, keyed_hmac, digest, rounds): """ py3-only implementation of pbkdf2 inner loop; uses 'int.from_bytes' + integer XOR """ from_bytes = int.from_bytes BIG = "big" # endianess doesn't matter, just has to be consistent accum = from_bytes(digest, BIG) for _ in irange(rounds - 1): digest = keyed_hmac(digest) accum ^= from_bytes(digest, BIG) return accum.to_bytes(digest_size, BIG) _builtin_backend = "from-bytes" elif _force_backend in ["any", "unpack", "from-bytes"]: from struct import Struct from passlib.utils import sys_bits _have_64_bit = (sys_bits >= 64) #: cache used by _get_pbkdf2_looper _looper_cache = {} def _get_pbkdf2_looper(digest_size): """ We want a helper function which performs equivalent of the following:: def helper(keyed_hmac, digest, rounds): accum = digest for _ in irange(rounds - 1): digest = keyed_hmac(digest) accum ^= digest return accum However, no efficient way to implement "bytes ^ bytes" in python. Instead, using approach where we dynamically compile a helper function based on digest size. Instead of a single `accum` var, this helper breaks the digest into a series of integers. It stores these in a series of`accum_<i>` vars, and performs `accum ^= digest` by unpacking digest and perform xor for each "accum_<i> ^= digest_<i>". this keeps everything in locals, avoiding excessive list creation, encoding or decoding, etc. :param digest_size: digest size to compile for, in bytes. (must be multiple of 4). :return: helper function with call signature outlined above. """ # # cache helpers # try: return _looper_cache[digest_size] except KeyError: pass # # figure out most efficient struct format to unpack digest into list of native ints # if _have_64_bit and not digest_size & 0x7: # digest size multiple of 8, on a 64 bit system -- use array of UINT64 count = (digest_size >> 3) fmt = "=%dQ" % count elif not digest_size & 0x3: if _have_64_bit: # digest size multiple of 4, on a 64 bit system -- use array of UINT64 + 1 UINT32 count = (digest_size >> 3) fmt = "=%dQI" % count count += 1 else: # digest size multiple of 4, on a 32 bit system -- use array of UINT32 count = (digest_size >> 2) fmt = "=%dI" % count else: # stopping here, cause no known hashes have digest size that isn't multiple of 4 bytes. # if needed, could go crazy w/ "H" & "B" raise NotImplementedError("unsupported digest size: %d" % digest_size) struct = Struct(fmt) # # build helper source # tdict = dict( digest_size=digest_size, accum_vars=", ".join("acc_%d" % i for i in irange(count)), digest_vars=", ".join("dig_%d" % i for i in irange(count)), ) # head of function source = ( "def helper(keyed_hmac, digest, rounds):\n" " '''pbkdf2 loop helper for digest_size={digest_size}'''\n" " unpack_digest = struct.unpack\n" " {accum_vars} = unpack_digest(digest)\n" " for _ in irange(1, rounds):\n" " digest = keyed_hmac(digest)\n" " {digest_vars} = unpack_digest(digest)\n" ).format(**tdict) # xor digest for i in irange(count): source += " acc_%d ^= dig_%d\n" % (i, i) # return result source += " return struct.pack({accum_vars})\n".format(**tdict) # # compile helper # code = compile(source, "<generated by passlib.crypto.digest._get_pbkdf2_looper()>", "exec") gdict = dict(irange=irange, struct=struct) ldict = dict() eval(code, gdict, ldict) helper = ldict['helper'] if __debug__: helper.__source__ = source # # store in cache # _looper_cache[digest_size] = helper return helper _builtin_backend = "unpack" else: assert _force_backend in ["any", "hexlify"] # XXX: older & slower approach that used int(hexlify()), # keeping it around for a little while just for benchmarking. from binascii import hexlify as _hexlify from passlib.utils import int_to_bytes def _get_pbkdf2_looper(digest_size): return _pbkdf2_looper def _pbkdf2_looper(keyed_hmac, digest, rounds): hexlify = _hexlify accum = int(hexlify(digest), 16) for _ in irange(rounds - 1): digest = keyed_hmac(digest) accum ^= int(hexlify(digest), 16) return int_to_bytes(accum, len(digest)) _builtin_backend = "hexlify" # helper for benchmark script -- disable hashlib, fastpbkdf2 support if builtin requested if _force_backend == _builtin_backend: _fast_pbkdf2_hmac = _stdlib_pbkdf2_hmac = None # expose info about what backends are active PBKDF2_BACKENDS = [b for b in [ "fastpbkdf2" if _fast_pbkdf2_hmac else None, "hashlib-ssl" if _stdlib_pbkdf2_hmac else None, "builtin-" + _builtin_backend ] if b] # *very* rough estimate of relative speed (compared to sha256 using 'unpack' backend on 64bit arch) if "fastpbkdf2" in PBKDF2_BACKENDS: PBKDF2_SPEED_FACTOR = 3 elif "hashlib-ssl" in PBKDF2_BACKENDS: PBKDF2_SPEED_FACTOR = 1.4 else: # remaining backends have *some* difference in performance, but not enough to matter PBKDF2_SPEED_FACTOR = 1 #============================================================================= # eof #=============================================================================
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