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Re: Pure Python Data Mangling or Encrypting

From alister <alister.nospam.ware@ntlworld.com>
Newsgroups comp.lang.python
Subject Re: Pure Python Data Mangling or Encrypting
Date 2015-07-01 08:06 +0000
Organization Aioe.org NNTP Server
Message-ID <mn071s$i65$1@speranza.aioe.org> (permalink)
References (13 earlier) <mailman.171.1435611181.3674.python-list@python.org> <5592065e$0$1675$c3e8da3$5496439d@news.astraweb.com> <mailman.198.1435685990.3674.python-list@python.org> <5592e71e$0$1674$c3e8da3$5496439d@news.astraweb.com> <slrnmp69d1.1nu.jon+usenet@frosty.unequivocal.co.uk>

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On Tue, 30 Jun 2015 23:25:01 +0000, Jon Ribbens wrote:

> On 2015-06-30, Steven D'Aprano <steve@pearwood.info> wrote:
>> I don't think there has been much research into keeping at least *some*
>> security even when keys have been compromised, apart from as it relates
>> to two-factor authentication.
> 
> That's because "the key" is all the secret part. If an attacker knows
> the algorithm, and the key, and the ciphertext, then *by definition* all
> is lost. If you mean keeping the algorithm secret too then that's just
> considered bad crypto.
> 
>> In the past, and still today among people who don't understand
>> Kerckhoffs' principle, people have tried to keep the cipher secret and
>> not have a key at all. E.g. atbash, or caesar cipher, which once upon a
>> time were cutting edge ciphers, as laughably insecure as they are
>> today. If the method was compromised, all was lost.
> 
> Caesar cipher has a key. It's just very small, so is easy to guess.
> 
>> Today, if the key is compromised, all is lost. Is it possible that
>> there are ciphers that are resistant to discovery of the key? Obviously
>> if you know the key you can read encrypted messages, that's what the
>> key is for, but there are scenarios where you would want security to
>> degrade gracefully instead of in a brittle all-or-nothing manner:
>>
>> - even if the attacker can read my messages, he cannot tamper with
>>   them or write new ones as me.
> 
> I suppose that could be achieved by having separate encryption and
> signing keys, but you could do the same but better by encrypting with
> multiple algorithms. It's not an unstudied area:
> https://en.wikipedia.org/wiki/Multiple_encryption

"The kipper flies at Midnight"

(from almost every WWII spy movie ever)
even if this message is decoded it is meaningless unless the attacker 
also has the meanings of the Code phrases
(which would mean your agent had been captured anyway)



-- 
That's the funniest thing I've ever heard and I will _not_ condone it.
        -- DyerMaker, 17 March 2000 MegaPhone radio show

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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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