/usr/lib/python2.7/dist-packages/passlib/utils/h64.py is in python-passlib 1.5.3-0ubuntu3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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#=================================================================================
#imports
#=================================================================================
#core
import logging; log = logging.getLogger(__name__)
#site
#pkg
from passlib.utils import bytes, bjoin, bchrs, bord, belem_join
#local
__all__ = [
"CHARS",
"decode_bytes", "encode_bytes",
"decode_transposed_bytes", "encode_transposed_bytes",
"decode_int6", "encode_int6",
"decode_int12", "encode_int12"
"decode_int18", "encode_int18"
"decode_int24", "encode_int24",
"decode_int64", "encode_int64",
"decode_int", "encode_int",
]
#=================================================================================
#6 bit value <-> char mapping, and other internal helpers
#=================================================================================
#: hash64 char sequence
CHARS = u"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
BCHARS = CHARS.encode("ascii")
#: encode int -> hash64 char as efficiently as possible, w/ minimal checking
# Py2k #
_encode_6bit = BCHARS.__getitem__
# Py3k #
#_encode_6bit = lambda v: BCHARS[v:v+1]
# end Py3k #
#: decode hash64 char -> int as efficiently as possible, w/ minimal checking
_CHARIDX = dict((_encode_6bit(i),i) for i in xrange(64))
_decode_6bit = _CHARIDX.__getitem__ # char -> int
#for py3, enhance _CHARIDX to also support int value of bytes
# Py3k #
#_CHARIDX.update((v,i) for i,v in enumerate(BCHARS))
# end Py3k #
#=================================================================================
#encode offsets from buffer - used by md5_crypt, sha_crypt, et al
#=================================================================================
def _encode_bytes_helper(source):
#FIXME: do something much more efficient here.
# can't quite just use base64 and then translate chars,
# since this scheme is little-endian.
end = len(source)
tail = end % 3
end -= tail
idx = 0
while idx < end:
v1 = bord(source[idx])
v2 = bord(source[idx+1])
v3 = bord(source[idx+2])
yield encode_int24(v1 + (v2<<8) + (v3<<16))
idx += 3
if tail:
v1 = bord(source[idx])
if tail == 1:
#NOTE: 4 msb of int are always 0
yield encode_int12(v1)
else:
#NOTE: 2 msb of int are always 0
v2 = bord(source[idx+1])
yield encode_int18(v1 + (v2<<8))
def encode_bytes(source):
"encode byte string to h64 format"
if not isinstance(source, bytes):
raise TypeError("source must be bytes, not %s" % (type(source),))
return bjoin(_encode_bytes_helper(source))
def _decode_bytes_helper(source):
end = len(source)
tail = end % 4
if tail == 1:
#only 6 bits left, can't encode a whole byte!
raise ValueError("input string length cannot be == 1 mod 4")
end -= tail
idx = 0
while idx < end:
v = decode_int24(source[idx:idx+4])
yield bchrs(v&0xff, (v>>8)&0xff, v>>16)
idx += 4
if tail:
if tail == 2:
#NOTE: 2 msb of int are ignored (should be 0)
v = decode_int12(source[idx:idx+2])
yield bchrs(v&0xff)
else:
#NOTE: 4 msb of int are ignored (should be 0)
v = decode_int18(source[idx:idx+3])
yield bchrs(v&0xff, (v>>8)&0xff)
def decode_bytes(source):
"decode h64 format into byte string"
if not isinstance(source, bytes):
raise TypeError("source must be bytes, not %s" % (type(source),))
return bjoin(_decode_bytes_helper(source))
def encode_transposed_bytes(source, offsets):
"encode byte string to h64 format, using offset list to transpose elements"
if not isinstance(source, bytes):
raise TypeError("source must be bytes, not %s" % (type(source),))
#XXX: could make this a dup of encode_bytes(), which directly accesses source[offsets[idx]],
# but speed isn't *that* critical for this function
tmp = belem_join(source[off] for off in offsets)
return encode_bytes(tmp)
def decode_transposed_bytes(source, offsets):
"decode h64 format into byte string, then undoing specified transposition; inverse of :func:`encode_transposed_bytes`"
#NOTE: if transposition does not use all bytes of source, original can't be recovered
tmp = decode_bytes(source)
buf = [None] * len(offsets)
for off, char in zip(offsets, tmp):
buf[off] = char
return belem_join(buf)
#=================================================================================
# int <-> b64 string, used by des_crypt, bsdi_crypt
#=================================================================================
def decode_int6(source):
"decodes single hash64 character -> 6-bit integer"
if not isinstance(source, bytes):
raise TypeError("source must be bytes, not %s" % (type(source),))
try:
return _decode_6bit(source)
except KeyError:
raise ValueError("invalid character")
def encode_int6(value):
"encodes 6-bit integer -> single hash64 character"
if value < 0 or value > 63:
raise ValueError("value out of range")
return _encode_6bit(value)
#---------------------------------------------------------------------
def decode_int12(source):
"decodes 2 char hash64 string -> 12-bit integer (little-endian order)"
#NOTE: this is optimized form of decode_int(value) for 4 chars
if not isinstance(source, bytes):
raise TypeError("source must be bytes, not %s" % (type(source),))
try:
return (_decode_6bit(source[1])<<6)+_decode_6bit(source[0])
except KeyError:
raise ValueError("invalid character")
def encode_int12(value):
"encodes 12-bit integer -> 2 char hash64 string (little-endian order)"
#NOTE: this is optimized form of encode_int(value,2)
return _encode_6bit(value & 0x3f) + _encode_6bit((value>>6) & 0x3f)
#---------------------------------------------------------------------
def decode_int18(source):
"decodes 3 char hash64 string -> 18-bit integer (little-endian order)"
#NOTE: this is optimized form of decode_int(value) for 3 chars
if not isinstance(source, bytes):
raise TypeError("source must be bytes, not %s" % (type(source),))
return (
_decode_6bit(source[0]) +
(_decode_6bit(source[1])<<6) +
(_decode_6bit(source[2])<<12)
)
def encode_int18(value):
"encodes 18-bit integer -> 3 char hash64 string (little-endian order)"
#NOTE: this is optimized form of encode_int(value,3)
return (
_encode_6bit(value & 0x3f) +
_encode_6bit((value>>6) & 0x3f) +
_encode_6bit((value>>12) & 0x3f)
)
#---------------------------------------------------------------------
def decode_int24(source):
"decodes 4 char hash64 string -> 24-bit integer (little-endian order)"
#NOTE: this is optimized form of decode_int(source) for 4 chars
if not isinstance(source, bytes):
raise TypeError("source must be bytes, not %s" % (type(source),))
try:
return _decode_6bit(source[0]) +\
(_decode_6bit(source[1])<<6)+\
(_decode_6bit(source[2])<<12)+\
(_decode_6bit(source[3])<<18)
except KeyError:
raise ValueError("invalid character")
def encode_int24(value):
"encodes 24-bit integer -> 4 char hash64 string (little-endian order)"
#NOTE: this is optimized form of encode_int(value,4)
return _encode_6bit(value & 0x3f) + \
_encode_6bit((value>>6) & 0x3f) + \
_encode_6bit((value>>12) & 0x3f) + \
_encode_6bit((value>>18) & 0x3f)
#---------------------------------------------------------------------
def decode_int64(source):
"decodes 11 char hash64 string -> 64-bit integer (little-endian order; 2 msb assumed to be padding)"
return decode_int(source)
def encode_int64(value):
"encodes 64-bit integer -> 11 char hash64 string (little-endian order; 2 msb of 0's added as padding)"
return encode_int(value, 11)
def decode_dc_int64(source):
"""decode 11 char hash64 string -> 64-bit integer (big-endian order; 2 lsb assumed to be padding)
this format is used primarily by des-crypt & variants to encode the DES output value
used as a checksum.
"""
return decode_int(source, True)>>2
def encode_dc_int64(value):
"""encode 64-bit integer -> 11 char hash64 string (big-endian order; 2 lsb added as padding)
this format is used primarily by des-crypt & variants to encode the DES output value
used as a checksum.
"""
#NOTE: insert 2 padding bits as lsb, to make 66 bits total
return encode_int(value<<2,11,True)
#---------------------------------------------------------------------
def decode_int(source, big=False):
"""decode hash64 string -> integer
:arg source: hash64 string of any length
:arg big: if ``True``, big-endian encoding is used instead of little-endian (the default).
:raises ValueError: if the string contains invalid hash64 characters.
:returns:
a integer whose value is in ``range(0,2**(6*len(source)))``
"""
if not isinstance(source, bytes):
raise TypeError("source must be bytes, not %s" % (type(source),))
#FORMAT: little-endian, each char contributes 6 bits,
# char value = index in H64_CHARS string
if not big:
source = reversed(source)
try:
out = 0
for c in source:
#NOTE: under py3, 'c' is int, relying on _CHARIDX to support this.
out = (out<<6) + _decode_6bit(c)
return out
except KeyError:
raise ValueError("invalid character in string")
def encode_int(value, count, big=False):
"""encode integer into hash-64 format
:arg value: non-negative integer to encode
:arg count: number of output characters / 6 bit chunks to encode
:arg big: if ``True``, big-endian encoding is used instead of little-endian (the default).
:returns:
a hash64 string of length ``count``.
"""
if value < 0:
raise ValueError("value cannot be negative")
if big:
itr = xrange(6*count-6, -6, -6)
else:
itr = xrange(0, 6*count, 6)
return bjoin(
_encode_6bit((value>>off) & 0x3f)
for off in itr
)
#=================================================================================
#eof
#=================================================================================
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