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Groups > comp.lang.python > #93293

Re: Pure Python Data Mangling or Encrypting

From Randall Smith <randall@tnr.cc>
Subject Re: Pure Python Data Mangling or Encrypting
Date 2015-06-29 15:46 -0500
References (11 earlier) <558d86b0$0$1659$c3e8da3$5496439d@news.astraweb.com> <mmkbij$dpm$1@ger.gmane.org> <CAPTjJmon4abegr01-+mo5aLML+gA3wnR_+_kTTU7gGuCn=xrDA@mail.gmail.com> <mailman.141.1435424948.3674.python-list@python.org> <slrnmp00qf.1nu.jon+usenet@frosty.unequivocal.co.uk>
Newsgroups comp.lang.python
Message-ID <mailman.170.1435610818.3674.python-list@python.org> (permalink)

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On 06/28/2015 09:21 AM, Jon Ribbens wrote:
> On 2015-06-27, Randall Smith <randall@tnr.cc> wrote:
>> Thankyou.  Nice points. I do think given the risks (there are always
>> risks) discussed, a successful attack of this nature is not very likely.
>>    Worse case, something that looks like this would land on the disk.
>>
>> crc32 checksum + translation table + malware
>>
>> with a generated base64 name and no extension.
>
> I'm not sure why you're bothering with the checksum, it doesn't seem
> to me that it buys you anything. Personally I'd do something like
> this (pseudocode):


Same reason newer filesystems like BTRFS use checkusms (BTRFS uses 
CRC32).  The storage machine runs periodic file integrity checks.  It 
has no control over the underlying filesystem.


>
>    def obfuscate(data):
>        encode_key = list(range(256))
>        random.shuffle(encode_key)
>        encode_key = bytes(encode_key)
>        decode_key = bytes(encode_key.index(i) for i in range(256))
>        return decode_key + data.translate(encode_key) + decode_key
>
>    def deobfuscate(data):
>        return data[256:-256].translate(data[:256])
>
> The reason for appending the key as well as prepending it is that some
> anti-virus or malware scanners may well look at the last part of the
> file first, so putting something entirely locally-generated there may
> add a bit of safety. You could also simply pad with nulls or something
> of course, but again I can imagine some tools skipping backwards past
> nulls.
>

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Re: Pure Python Data Mangling or Encrypting Randall Smith <randall@tnr.cc> - 2015-06-24 13:36 -0500
  Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve@pearwood.info> - 2015-06-25 14:07 +1000
    Re: Pure Python Data Mangling or Encrypting Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-06-24 21:27 -0700
      Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-06-25 19:25 +1000
        Re: Pure Python Data Mangling or Encrypting Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-06-25 02:41 -0700
        Re: Pure Python Data Mangling or Encrypting Chris Angelico <rosuav@gmail.com> - 2015-06-25 19:57 +1000
        Re: Pure Python Data Mangling or Encrypting Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-25 10:03 +0000
          Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve@pearwood.info> - 2015-06-26 01:13 +1000
            Re: Pure Python Data Mangling or Encrypting Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-25 15:26 +0000
              Re: Pure Python Data Mangling or Encrypting Randall Smith <randall@tnr.cc> - 2015-06-25 13:58 -0500
              Re: Pure Python Data Mangling or Encrypting Chris Angelico <rosuav@gmail.com> - 2015-06-26 10:33 +1000
                Re: Pure Python Data Mangling or Encrypting Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-26 10:49 +0000
              Re: Pure Python Data Mangling or Encrypting Ian Kelly <ian.g.kelly@gmail.com> - 2015-06-25 19:01 -0600
                Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve@pearwood.info> - 2015-06-27 03:06 +1000
                Re: Pure Python Data Mangling or Encrypting Randall Smith <randall@tnr.cc> - 2015-06-26 15:09 -0500
                Re: Pure Python Data Mangling or Encrypting Johannes Bauer <dfnsonfsduifb@gmx.de> - 2015-06-26 23:07 +0200
                Re: Pure Python Data Mangling or Encrypting Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-26 21:29 +0000
                Re: Pure Python Data Mangling or Encrypting Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-26 22:55 +0100
                Re: Pure Python Data Mangling or Encrypting Johannes Bauer <dfnsonfsduifb@gmx.de> - 2015-06-27 00:42 +0200
                Re: Pure Python Data Mangling or Encrypting Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-06-26 16:26 -0700
                Re: Pure Python Data Mangling or Encrypting Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-27 00:21 +0000
                Re: Pure Python Data Mangling or Encrypting Randall Smith <randall@tnr.cc> - 2015-06-26 19:55 -0500
                Re: Pure Python Data Mangling or Encrypting Johannes Bauer <dfnsonfsduifb@gmx.de> - 2015-06-27 07:24 +0200
                Re: Pure Python Data Mangling or Encrypting Randall Smith <randall@tnr.cc> - 2015-06-26 19:12 -0500
                Re: Pure Python Data Mangling or Encrypting Ian Kelly <ian.g.kelly@gmail.com> - 2015-06-26 15:58 -0600
                Re: Pure Python Data Mangling or Encrypting Randall Smith <randall@tnr.cc> - 2015-06-26 19:23 -0500
                Re: Pure Python Data Mangling or Encrypting Johannes Bauer <dfnsonfsduifb@gmx.de> - 2015-06-26 23:11 +0200
                Re: Pure Python Data Mangling or Encrypting Michael Torrie <torriem@gmail.com> - 2015-06-27 11:02 -0600
                Re: Pure Python Data Mangling or Encrypting Paul Rubin <no.email@nospam.invalid> - 2015-06-27 10:45 -0700
                Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve@pearwood.info> - 2015-06-27 13:38 +1000
                Re: Pure Python Data Mangling or Encrypting Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-06-26 21:05 -0700
                Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve@pearwood.info> - 2015-06-27 16:16 +1000
                Re: Pure Python Data Mangling or Encrypting Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-06-27 13:30 -0700
                Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve@pearwood.info> - 2015-06-28 11:18 +1000
                Re: Pure Python Data Mangling or Encrypting Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-06-27 19:11 -0700
                Re: Pure Python Data Mangling or Encrypting Ian Kelly <ian.g.kelly@gmail.com> - 2015-06-26 23:47 -0600
                Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve@pearwood.info> - 2015-06-27 18:38 +1000
                Re: Pure Python Data Mangling or Encrypting Chris Angelico <rosuav@gmail.com> - 2015-06-27 18:53 +1000
                Re: Pure Python Data Mangling or Encrypting Johannes Bauer <dfnsonfsduifb@gmx.de> - 2015-06-27 11:07 +0200
                Re: Pure Python Data Mangling or Encrypting Chris Angelico <rosuav@gmail.com> - 2015-06-27 19:17 +1000
                Re: Pure Python Data Mangling or Encrypting Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-27 09:27 +0000
                Re: Pure Python Data Mangling or Encrypting Johannes Bauer <dfnsonfsduifb@gmx.de> - 2015-06-27 12:05 +0200
                Re: Pure Python Data Mangling or Encrypting Chris Angelico <rosuav@gmail.com> - 2015-06-27 20:16 +1000
                Re: Pure Python Data Mangling or Encrypting Johannes Bauer <dfnsonfsduifb@gmx.de> - 2015-06-27 12:55 +0200
                Re: Pure Python Data Mangling or Encrypting Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-27 10:26 +0000
                Re: Pure Python Data Mangling or Encrypting Laura Creighton <lac@openend.se> - 2015-06-27 14:27 +0200
                Re: Pure Python Data Mangling or Encrypting Johannes Bauer <dfnsonfsduifb@gmx.de> - 2015-06-27 12:18 +0200
                Re: Pure Python Data Mangling or Encrypting Chris Angelico <rosuav@gmail.com> - 2015-06-27 21:33 +1000
                Re: Pure Python Data Mangling or Encrypting Ian Kelly <ian.g.kelly@gmail.com> - 2015-06-27 08:59 -0600
                Re: Pure Python Data Mangling or Encrypting Laura Creighton <lac@openend.se> - 2015-06-27 13:25 +0200
                Re: Pure Python Data Mangling or Encrypting Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2015-06-27 15:23 +0300
                Re: Pure Python Data Mangling or Encrypting Laura Creighton <lac@openend.se> - 2015-06-27 14:48 +0200
                Re: Pure Python Data Mangling or Encrypting Johannes Bauer <dfnsonfsduifb@gmx.de> - 2015-06-27 11:12 +0200
                Re: Pure Python Data Mangling or Encrypting Ian Kelly <ian.g.kelly@gmail.com> - 2015-06-27 09:09 -0600
                Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve@pearwood.info> - 2015-06-28 03:35 +1000
                Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve@pearwood.info> - 2015-06-28 03:58 +1000
                Re: Pure Python Data Mangling or Encrypting Ian Kelly <ian.g.kelly@gmail.com> - 2015-06-27 14:16 -0600
                Re: Pure Python Data Mangling or Encrypting Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-28 13:41 +0000
                Re: Pure Python Data Mangling or Encrypting Robert Kern <robert.kern@gmail.com> - 2015-06-27 08:58 +0100
                Re: Pure Python Data Mangling or Encrypting Robert Kern <robert.kern@gmail.com> - 2015-06-27 09:07 +0100
                Re: Pure Python Data Mangling or Encrypting Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-06-27 10:39 -0400
                Re: Pure Python Data Mangling or Encrypting Grant Edwards <invalid@invalid.invalid> - 2015-06-27 12:38 +0000
                Re: Pure Python Data Mangling or Encrypting Randall Smith <randall@tnr.cc> - 2015-06-27 13:22 -0500
                Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve@pearwood.info> - 2015-06-28 04:51 +1000
                Re: Pure Python Data Mangling or Encrypting Chris Angelico <rosuav@gmail.com> - 2015-06-28 09:05 +1000
                Re: Pure Python Data Mangling or Encrypting Chris Angelico <rosuav@gmail.com> - 2015-06-27 11:21 +1000
                Re: Pure Python Data Mangling or Encrypting Ian Kelly <ian.g.kelly@gmail.com> - 2015-06-26 23:59 -0600
                Re: Pure Python Data Mangling or Encrypting Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-27 09:26 +0000
                Re: Pure Python Data Mangling or Encrypting Chris Angelico <rosuav@gmail.com> - 2015-06-27 16:52 +1000
                Re: Pure Python Data Mangling or Encrypting Randall Smith <randall@tnr.cc> - 2015-06-27 12:08 -0500
                Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve@pearwood.info> - 2015-06-28 04:50 +1000
                Re: Pure Python Data Mangling or Encrypting Randall Smith <randall@tnr.cc> - 2015-06-29 15:52 -0500
                Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve@pearwood.info> - 2015-06-30 13:00 +1000
                Re: Pure Python Data Mangling or Encrypting Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-30 12:19 +0000
                Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve@pearwood.info> - 2015-07-01 04:17 +1000
                Re: Pure Python Data Mangling or Encrypting Chris Angelico <rosuav@gmail.com> - 2015-07-01 04:33 +1000
                Re: Pure Python Data Mangling or Encrypting Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-30 18:37 +0000
                Re: Pure Python Data Mangling or Encrypting Randall Smith <randall@tnr.cc> - 2015-07-01 09:38 -0500
                Re: Pure Python Data Mangling or Encrypting Randall Smith <randall@tnr.cc> - 2015-06-30 12:39 -0500
                Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve@pearwood.info> - 2015-07-01 04:59 +1000
                Re: Pure Python Data Mangling or Encrypting Chris Angelico <rosuav@gmail.com> - 2015-07-01 05:20 +1000
                Re: Pure Python Data Mangling or Encrypting Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-30 23:25 +0000
                Re: Pure Python Data Mangling or Encrypting alister <alister.nospam.ware@ntlworld.com> - 2015-07-01 08:06 +0000
                Re: Pure Python Data Mangling or Encrypting Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-28 14:21 +0000
                Re: Pure Python Data Mangling or Encrypting Randall Smith <randall@tnr.cc> - 2015-06-29 15:46 -0500
                Re: Pure Python Data Mangling or Encrypting Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-29 20:49 +0000
                Re: Pure Python Data Mangling or Encrypting Randall Smith <randall@tnr.cc> - 2015-06-30 12:43 -0500
                Re: Pure Python Data Mangling or Encrypting Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-07-02 10:31 +1200
              Re: Pure Python Data Mangling or Encrypting Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-26 02:17 +0100
              Re: Pure Python Data Mangling or Encrypting Chris Angelico <rosuav@gmail.com> - 2015-06-26 12:06 +1000
              Re: Pure Python Data Mangling or Encrypting Chris Angelico <rosuav@gmail.com> - 2015-06-26 12:05 +1000
              Re: Pure Python Data Mangling or Encrypting Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-26 03:24 +0100
              Re: Pure Python Data Mangling or Encrypting Chris Angelico <rosuav@gmail.com> - 2015-06-26 12:29 +1000
        Re: Pure Python Data Mangling or Encrypting Joonas Liik <liik.joonas@gmail.com> - 2015-06-25 13:00 +0300
        Re: Pure Python Data Mangling or Encrypting Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-06-25 03:18 -0700
    Re: Pure Python Data Mangling or Encrypting Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-06-25 17:05 +1000
    Re: Pure Python Data Mangling or Encrypting Randall Smith <randall@tnr.cc> - 2015-06-25 14:09 -0500

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