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4581ae5fa2
Change binascii.Error to derive from ValueError and raise binascii.Error everywhere where values are bad (why on earth did the old code use TypeError?!?).
381 lines
12 KiB
Python
Executable File
381 lines
12 KiB
Python
Executable File
#! /usr/bin/env python
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"""RFC 3548: Base16, Base32, Base64 Data Encodings"""
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# Modified 04-Oct-1995 by Jack Jansen to use binascii module
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# Modified 30-Dec-2003 by Barry Warsaw to add full RFC 3548 support
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# Modified 22-May-2007 by Guido van Rossum to use bytes everywhere
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import re
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import struct
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import binascii
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__all__ = [
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# Legacy interface exports traditional RFC 1521 Base64 encodings
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'encode', 'decode', 'encodestring', 'decodestring',
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# Generalized interface for other encodings
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'b64encode', 'b64decode', 'b32encode', 'b32decode',
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'b16encode', 'b16decode',
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# Standard Base64 encoding
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'standard_b64encode', 'standard_b64decode',
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# Some common Base64 alternatives. As referenced by RFC 3458, see thread
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# starting at:
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#
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# http://zgp.org/pipermail/p2p-hackers/2001-September/000316.html
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'urlsafe_b64encode', 'urlsafe_b64decode',
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]
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def _translate(s, altchars):
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assert isinstance(s, bytes), type(s)
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translation = bytes(range(256))
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for k, v in altchars.items():
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translation[ord(k)] = v[0]
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return s.translate(translation)
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# Base64 encoding/decoding uses binascii
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def b64encode(s, altchars=None):
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"""Encode a byte string using Base64.
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s is the byte string to encode. Optional altchars must be a byte
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string of length 2 which specifies an alternative alphabet for the
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'+' and '/' characters. This allows an application to
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e.g. generate url or filesystem safe Base64 strings.
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The encoded byte string is returned.
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"""
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if not isinstance(s, bytes):
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s = bytes(s)
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# Strip off the trailing newline
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encoded = binascii.b2a_base64(s)[:-1]
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if altchars is not None:
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if not isinstance(altchars, bytes):
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altchars = bytes(altchars)
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assert len(altchars) == 2, repr(altchars)
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return _translate(encoded, {'+': altchars[0:1], '/': altchars[1:2]})
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return encoded
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def b64decode(s, altchars=None):
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"""Decode a Base64 encoded byte string.
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s is the byte string to decode. Optional altchars must be a
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string of length 2 which specifies the alternative alphabet used
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instead of the '+' and '/' characters.
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The decoded byte string is returned. binascii.Error is raised if
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s were incorrectly padded or if there are non-alphabet characters
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present in the string.
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"""
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if not isinstance(s, bytes):
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s = bytes(s)
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if altchars is not None:
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if not isinstance(altchars, bytes):
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altchars = bytes(altchars)
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assert len(altchars) == 2, repr(altchars)
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s = _translate(s, {chr(altchars[0]): b'+', chr(altchars[1]): b'/'})
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return binascii.a2b_base64(s)
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def standard_b64encode(s):
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"""Encode a byte string using the standard Base64 alphabet.
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s is the byte string to encode. The encoded byte string is returned.
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"""
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return b64encode(s)
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def standard_b64decode(s):
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"""Decode a byte string encoded with the standard Base64 alphabet.
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s is the byte string to decode. The decoded byte string is
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returned. binascii.Error is raised if the input is incorrectly
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padded or if there are non-alphabet characters present in the
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input.
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"""
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return b64decode(s)
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def urlsafe_b64encode(s):
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"""Encode a byte string using a url-safe Base64 alphabet.
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s is the byte string to encode. The encoded byte string is
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returned. The alphabet uses '-' instead of '+' and '_' instead of
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'/'.
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"""
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return b64encode(s, b'-_')
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def urlsafe_b64decode(s):
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"""Decode a byte string encoded with the standard Base64 alphabet.
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s is the byte string to decode. The decoded byte string is
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returned. binascii.Error is raised if the input is incorrectly
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padded or if there are non-alphabet characters present in the
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input.
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The alphabet uses '-' instead of '+' and '_' instead of '/'.
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"""
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return b64decode(s, b'-_')
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# Base32 encoding/decoding must be done in Python
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_b32alphabet = {
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0: b'A', 9: b'J', 18: b'S', 27: b'3',
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1: b'B', 10: b'K', 19: b'T', 28: b'4',
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2: b'C', 11: b'L', 20: b'U', 29: b'5',
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3: b'D', 12: b'M', 21: b'V', 30: b'6',
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4: b'E', 13: b'N', 22: b'W', 31: b'7',
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5: b'F', 14: b'O', 23: b'X',
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6: b'G', 15: b'P', 24: b'Y',
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7: b'H', 16: b'Q', 25: b'Z',
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8: b'I', 17: b'R', 26: b'2',
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}
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_b32tab = [v[0] for k, v in sorted(_b32alphabet.items())]
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_b32rev = dict([(v[0], k) for k, v in _b32alphabet.items()])
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def b32encode(s):
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"""Encode a byte string using Base32.
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s is the byte string to encode. The encoded byte string is returned.
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"""
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if not isinstance(s, bytes):
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s = bytes(s)
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quanta, leftover = divmod(len(s), 5)
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# Pad the last quantum with zero bits if necessary
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if leftover:
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s = s + bytes(5 - leftover) # Don't use += !
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quanta += 1
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encoded = bytes()
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for i in range(quanta):
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# c1 and c2 are 16 bits wide, c3 is 8 bits wide. The intent of this
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# code is to process the 40 bits in units of 5 bits. So we take the 1
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# leftover bit of c1 and tack it onto c2. Then we take the 2 leftover
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# bits of c2 and tack them onto c3. The shifts and masks are intended
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# to give us values of exactly 5 bits in width.
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c1, c2, c3 = struct.unpack('!HHB', s[i*5:(i+1)*5])
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c2 += (c1 & 1) << 16 # 17 bits wide
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c3 += (c2 & 3) << 8 # 10 bits wide
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encoded += bytes([_b32tab[c1 >> 11], # bits 1 - 5
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_b32tab[(c1 >> 6) & 0x1f], # bits 6 - 10
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_b32tab[(c1 >> 1) & 0x1f], # bits 11 - 15
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_b32tab[c2 >> 12], # bits 16 - 20 (1 - 5)
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_b32tab[(c2 >> 7) & 0x1f], # bits 21 - 25 (6 - 10)
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_b32tab[(c2 >> 2) & 0x1f], # bits 26 - 30 (11 - 15)
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_b32tab[c3 >> 5], # bits 31 - 35 (1 - 5)
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_b32tab[c3 & 0x1f], # bits 36 - 40 (1 - 5)
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])
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# Adjust for any leftover partial quanta
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if leftover == 1:
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return encoded[:-6] + b'======'
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elif leftover == 2:
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return encoded[:-4] + b'===='
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elif leftover == 3:
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return encoded[:-3] + b'==='
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elif leftover == 4:
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return encoded[:-1] + b'='
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return encoded
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def b32decode(s, casefold=False, map01=None):
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"""Decode a Base32 encoded byte string.
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s is the byte string to decode. Optional casefold is a flag
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specifying whether a lowercase alphabet is acceptable as input.
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For security purposes, the default is False.
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RFC 3548 allows for optional mapping of the digit 0 (zero) to the
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letter O (oh), and for optional mapping of the digit 1 (one) to
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either the letter I (eye) or letter L (el). The optional argument
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map01 when not None, specifies which letter the digit 1 should be
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mapped to (when map01 is not None, the digit 0 is always mapped to
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the letter O). For security purposes the default is None, so that
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0 and 1 are not allowed in the input.
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The decoded byte string is returned. binascii.Error is raised if
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the input is incorrectly padded or if there are non-alphabet
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characters present in the input.
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"""
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if not isinstance(s, bytes):
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s = bytes(s)
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quanta, leftover = divmod(len(s), 8)
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if leftover:
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raise binascii.Error('Incorrect padding')
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# Handle section 2.4 zero and one mapping. The flag map01 will be either
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# False, or the character to map the digit 1 (one) to. It should be
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# either L (el) or I (eye).
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if map01:
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if not isinstance(map01, bytes):
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map01 = bytes(map01)
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assert len(map01) == 1, repr(map01)
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s = _translate(s, {'0': b'O', '1': map01})
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if casefold:
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s = bytes(str(s, "ascii").upper(), "ascii")
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# Strip off pad characters from the right. We need to count the pad
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# characters because this will tell us how many null bytes to remove from
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# the end of the decoded string.
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padchars = 0
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mo = re.search('(?P<pad>[=]*)$', s)
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if mo:
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padchars = len(mo.group('pad'))
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if padchars > 0:
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s = s[:-padchars]
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# Now decode the full quanta
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parts = []
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acc = 0
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shift = 35
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for c in s:
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val = _b32rev.get(c)
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if val is None:
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raise TypeError('Non-base32 digit found')
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acc += _b32rev[c] << shift
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shift -= 5
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if shift < 0:
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parts.append(binascii.unhexlify('%010x' % acc))
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acc = 0
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shift = 35
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# Process the last, partial quanta
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last = binascii.unhexlify(bytes('%010x' % acc))
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if padchars == 0:
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last = b'' # No characters
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elif padchars == 1:
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last = last[:-1]
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elif padchars == 3:
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last = last[:-2]
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elif padchars == 4:
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last = last[:-3]
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elif padchars == 6:
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last = last[:-4]
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else:
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raise binascii.Error('Incorrect padding')
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parts.append(last)
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return b''.join(parts)
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# RFC 3548, Base 16 Alphabet specifies uppercase, but hexlify() returns
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# lowercase. The RFC also recommends against accepting input case
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# insensitively.
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def b16encode(s):
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"""Encode a byte string using Base16.
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s is the byte string to encode. The encoded byte string is returned.
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"""
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return bytes(str(binascii.hexlify(s), "ascii").upper(), "ascii")
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def b16decode(s, casefold=False):
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"""Decode a Base16 encoded byte string.
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s is the byte string to decode. Optional casefold is a flag
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specifying whether a lowercase alphabet is acceptable as input.
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For security purposes, the default is False.
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The decoded byte string is returned. binascii.Error is raised if
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s were incorrectly padded or if there are non-alphabet characters
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present in the string.
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"""
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if not isinstance(s, bytes):
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s = bytes(s)
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if casefold:
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s = bytes(str(s, "ascii").upper(), "ascii")
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if re.search('[^0-9A-F]', s):
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raise binascii.Error('Non-base16 digit found')
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return binascii.unhexlify(s)
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# Legacy interface. This code could be cleaned up since I don't believe
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# binascii has any line length limitations. It just doesn't seem worth it
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# though. The files should be opened in binary mode.
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MAXLINESIZE = 76 # Excluding the CRLF
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MAXBINSIZE = (MAXLINESIZE//4)*3
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def encode(input, output):
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"""Encode a file."""
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while True:
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s = input.read(MAXBINSIZE)
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if not s:
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break
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while len(s) < MAXBINSIZE:
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ns = input.read(MAXBINSIZE-len(s))
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if not ns:
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break
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s += ns
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line = binascii.b2a_base64(s)
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output.write(line)
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def decode(input, output):
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"""Decode a file."""
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while True:
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line = input.readline()
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if not line:
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break
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s = binascii.a2b_base64(line)
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output.write(s)
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def encodestring(s):
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"""Encode a string into multiple lines of base-64 data."""
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if not isinstance(s, bytes):
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s = bytes(s)
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pieces = []
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for i in range(0, len(s), MAXBINSIZE):
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chunk = s[i : i + MAXBINSIZE]
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pieces.append(binascii.b2a_base64(chunk))
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return b"".join(pieces)
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def decodestring(s):
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"""Decode a string."""
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if not isinstance(s, bytes):
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s = bytes(s)
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return binascii.a2b_base64(s)
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# Usable as a script...
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def main():
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"""Small main program"""
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import sys, getopt
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try:
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opts, args = getopt.getopt(sys.argv[1:], 'deut')
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except getopt.error as msg:
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sys.stdout = sys.stderr
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print(msg)
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print("""usage: %s [-d|-e|-u|-t] [file|-]
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-d, -u: decode
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-e: encode (default)
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-t: encode and decode string 'Aladdin:open sesame'"""%sys.argv[0])
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sys.exit(2)
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func = encode
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for o, a in opts:
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if o == '-e': func = encode
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if o == '-d': func = decode
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if o == '-u': func = decode
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if o == '-t': test(); return
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if args and args[0] != '-':
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func(open(args[0], 'rb'), sys.stdout)
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else:
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func(sys.stdin, sys.stdout)
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def test():
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s0 = b"Aladdin:open sesame"
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print(repr(s0))
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s1 = encodestring(s0)
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print(repr(s1))
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s2 = decodestring(s1)
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print(repr(s2))
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assert s0 == s2
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if __name__ == '__main__':
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main()
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