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Groups > comp.lang.python > #82814

Re: Encryption - was Hello World

Date 2014-12-22 18:22 -0500
From Dave Angel <davea@davea.name>
Subject Re: Encryption - was Hello World
References (3 earlier) <roy-2DE8D9.18502021122014@news.panix.com> <m79ghk$o5r$3@reader1.panix.com> <CAPTjJmoJNX2swk-PQyZw8=Z05=kOxhHNdtgpZ2bUEuX0c7+4bw@mail.gmail.com> <54987797.8060504@davea.name> <CAPTjJmrWN8dJS3rNJGFB+cK=RLzsXwdYkCxyP=zRkDsofEyteg@mail.gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.17141.1419290548.18130.python-list@python.org> (permalink)

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On 12/22/2014 05:29 PM, Chris Angelico wrote:
> On Tue, Dec 23, 2014 at 6:57 AM, Dave Angel <d@davea.name> wrote:
>> I figure I must be misunderstanding something in your explanation, since a
>> brute-force password guesser would seem to only need four billion tries to
>> (probably) crack that.
>>
     <snip>
>
> As to the assumptions... uhh... that was never something I really
> understood. I think you're probably right, and this was part of the
> paranoia of "my code might be stolen". You're attempting to attribute
> a level of logic to the requirements which has no supporting evidence
> :)
>

I recall a DLL that implemented the license check, and an application 
called a function in the DLL and looked for true or false.  Even the 
exported function name was a pretty good clue.  And extremely easy to 
intercept and defeat.  I did convince the company (my employer, though I 
didn't normally work on the license stuff) to statically link instead. 
And to stop shipping all the symbols with the executable.  Most security 
flaws are of this form, not sophisticated cracking.

I also wrote my own form of protection in 1976 to make it difficult for 
somebody to retrieve source.  The previous version had simply added a 
protect bit to the image file.  Mine saved a completely different file 
every time you re-saved the program data, to try to make it hard (not 
impossible) to recover it.  Then it stored a separate key in each sector 
of the file so reading it into the interpreter was always possible.  I 
had a couple of constraints - the file couldn't grow, and it had to be 
fast enough to have no impact on load time.

I had a guy claim that the CIA got interested in the code, and cracked 
it during a lunch hour.  But I suspect somebody got hold of the source 
code, which was available to our field service staff.

There were a couple of iterations before this code was stable.  Not in 
the algorithm, but in what amounted to a few back-doors.  For example, 
it turns out the error display logic would show the line in error, 
unencrypted.  So people would munge the code sufficiently to cause 
errors on most lines, and retrieve them one at a time.

Another thing I did in 1976 which was apparently unusual was to add a 
checksum to the code itself.  The Boot Rom would self-check before 
starting the machine, and it also checksummed the loadable microcode 
before passing control to it.  Prevented some corruption problems.

Another thing that machine did was to run a RAM diagnostic from the time 
it booted till the operator specified the drive from which to fetch the 
microcode.  The entire test took many minutes to run, but it was 
entirely silent unless a problem occurred.  No pass counts or anything. 
  When I added that code, manufacturing found some machines that had 
been put aside as flaky, actually had RAM errors.  The test was 
necessary crude, because the entire boot, including disk logic, had to 
fit in 1k.

Ahh... memories.

-- 
DaveA

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Hello World Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-20 23:57 +1100
  Re: Hello World Chris Angelico <rosuav@gmail.com> - 2014-12-21 00:11 +1100
  Re: Hello World Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-12-20 16:13 +0000
  Re: Hello World Rustom Mody <rustompmody@gmail.com> - 2014-12-20 08:50 -0800
  Re: Hello World Steve Hayes <hayesstw@telkomsa.net> - 2014-12-20 20:39 +0200
  Re: Hello World alister <alister.nospam.ware@ntlworld.com> - 2014-12-20 22:18 +0000
  Re: Hello World CM <cmpython@gmail.com> - 2014-12-20 21:14 -0800
    Re: Hello World Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-21 16:26 +1100
    Re: Hello World Chris Angelico <rosuav@gmail.com> - 2014-12-21 16:31 +1100
    Re: Hello World Terry Reedy <tjreedy@udel.edu> - 2014-12-21 01:31 -0500
      Re: Hello World wxjmfauth@gmail.com - 2014-12-21 00:07 -0800
    Re: Hello World Chris Angelico <rosuav@gmail.com> - 2014-12-21 17:44 +1100
      Re: Hello World CM <cmpython@gmail.com> - 2014-12-20 23:44 -0800
        Re: Hello World CM <cmpython@gmail.com> - 2014-12-20 23:45 -0800
          Re: Hello World Marko Rauhamaa <marko@pacujo.net> - 2014-12-21 10:26 +0200
        Re: Hello World Chris Angelico <rosuav@gmail.com> - 2014-12-21 18:46 +1100
      Re: Hello World albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-01-08 12:43 +0000
        Re: Hello World Chris Angelico <rosuav@gmail.com> - 2015-01-08 23:53 +1100
          Re: Hello World albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-01-08 13:37 +0000
          Re: Hello World Marko Rauhamaa <marko@pacujo.net> - 2015-01-08 16:06 +0200
            Re: Hello World alister <alister.nospam.ware@ntlworld.com> - 2015-01-08 14:21 +0000
              Re: Hello World Marko Rauhamaa <marko@pacujo.net> - 2015-01-08 16:31 +0200
                Re: Hello World alister <alister.nospam.ware@ntlworld.com> - 2015-01-08 15:14 +0000
          Re: Hello World Michael Ströder <michael@stroeder.com> - 2015-01-08 15:11 +0100
          Re: Hello World albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-01-17 14:51 +0000
            Re: Hello World Chris Angelico <rosuav@gmail.com> - 2015-01-18 01:57 +1100
              Re: Hello World cl@isbd.net - 2015-01-17 15:18 +0000
            Re: Hello World Michael Torrie <torriem@gmail.com> - 2015-01-17 09:29 -0700
              Re: Hello World cl@isbd.net - 2015-01-17 16:47 +0000
                Re: Hello World albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-01-17 18:06 +0000
                Re: Hello World Michael Ströder <michael@stroeder.com> - 2015-01-17 19:47 +0100
                Re: Hello World Michael Torrie <torriem@gmail.com> - 2015-01-17 19:09 -0700
                Re: Hello World Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-18 13:37 +1100
                Re: Hello World Roy Smith <roy@panix.com> - 2015-01-17 22:18 -0500
                Re: Hello World Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-18 14:45 +1100
                Re: Hello World Chris Angelico <rosuav@gmail.com> - 2015-01-18 18:45 +1100
                Re: Hello World Roy Smith <roy@panix.com> - 2015-01-18 07:26 -0500
                Re: Hello World Tim Chase <python.list@tim.thechases.com> - 2015-01-17 21:50 -0600
                Re: Hello World Chris Angelico <rosuav@gmail.com> - 2015-01-18 18:44 +1100
                Re: Hello World Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-01-17 18:31 +0000
                Re: Hello World Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-18 10:46 +1100
                Re: Hello World Chris Angelico <rosuav@gmail.com> - 2015-01-18 11:04 +1100
                Re: Hello World Jason Friedman <jsf80238@gmail.com> - 2015-01-17 18:19 -0700
                Re: Hello World Michael Torrie <torriem@gmail.com> - 2015-01-17 19:13 -0700
                Re: Hello World Marko Rauhamaa <marko@pacujo.net> - 2015-01-18 12:03 +0200
                Re: Hello World Michael Ströder <michael@stroeder.com> - 2015-01-18 14:34 +0100
                Re: Hello World Marko Rauhamaa <marko@pacujo.net> - 2015-01-18 18:03 +0200
                Re: Hello World Michael Ströder <michael@stroeder.com> - 2015-01-18 19:39 +0100
                Re: Hello World Chris Angelico <rosuav@gmail.com> - 2015-01-18 21:10 +1100
                Re: Hello World Marko Rauhamaa <marko@pacujo.net> - 2015-01-18 22:50 +0200
                Re: Hello World Michael Ströder <michael@stroeder.com> - 2015-01-18 14:32 +0100
                Re: Hello World Chris Angelico <rosuav@gmail.com> - 2015-01-18 21:00 +1100
                Re: Hello World Michael Ströder <michael@stroeder.com> - 2015-01-18 14:35 +0100
                Re: Hello World Chris Angelico <rosuav@gmail.com> - 2015-01-19 00:57 +1100
                Re: Hello World Michael Ströder <michael@stroeder.com> - 2015-01-18 16:48 +0100
                Re: Hello World Chris Angelico <rosuav@gmail.com> - 2015-01-19 04:08 +1100
                Re: Hello World Michael Ströder <michael@stroeder.com> - 2015-01-18 14:30 +0100
        Re: Hello World Steve Hayes <hayesstw@telkomsa.net> - 2015-01-08 19:02 +0200
          Re: Hello World Chris Angelico <rosuav@gmail.com> - 2015-01-09 04:11 +1100
            Re: Hello World albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-01-17 15:10 +0000
          Re: Hello World Michael Torrie <torriem@gmail.com> - 2015-01-08 10:53 -0700
            Re: Hello World Grant Edwards <invalid@invalid.invalid> - 2015-01-08 18:57 +0000
    Re: Hello World Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-01-17 16:06 -0800
  Re: Hello World Tony the Tiger <tony@tiger.invalid> - 2014-12-21 19:22 +0000
    Re: Hello World Marko Rauhamaa <marko@pacujo.net> - 2014-12-21 22:02 +0200
    Re: Hello World Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-22 09:51 +1100
      Re: Hello World Roy Smith <roy@panix.com> - 2014-12-21 18:50 -0500
        Re: Hello World Chris Angelico <rosuav@gmail.com> - 2014-12-22 11:10 +1100
          Re: Hello World Roy Smith <roy@panix.com> - 2014-12-21 19:12 -0500
            Re: Hello World Chris Angelico <rosuav@gmail.com> - 2014-12-22 11:36 +1100
          Re: Hello World mm0fmf <none@mailinator.com> - 2014-12-22 00:20 +0000
            Re: Hello World Tim Chase <python.list@tim.thechases.com> - 2014-12-21 18:47 -0600
            Re: Hello World Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-12-22 02:56 +0000
          Re: Hello World Marko Rauhamaa <marko@pacujo.net> - 2014-12-22 10:52 +0200
            Re: Hello World Chris Angelico <rosuav@gmail.com> - 2014-12-22 20:01 +1100
        Re: Hello World Grant Edwards <invalid@invalid.invalid> - 2014-12-22 16:23 +0000
          Re: Hello World Chris Angelico <rosuav@gmail.com> - 2014-12-23 04:25 +1100
          Re: Hello World Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-12-22 18:51 +0000
          Re: Hello World MRAB <python@mrabarnett.plus.com> - 2014-12-22 19:05 +0000
          Re: Hello World Tim Chase <python.list@tim.thechases.com> - 2014-12-22 13:16 -0600
            Re: Hello World Roy Smith <roy@panix.com> - 2014-12-22 19:55 -0500
              Re: Hello World sohcahtoa82@gmail.com - 2014-12-22 17:03 -0800
                Re: Hello World MRAB <python@mrabarnett.plus.com> - 2014-12-23 01:37 +0000
                Re: Hello World Chris Angelico <rosuav@gmail.com> - 2014-12-23 12:39 +1100
                Re: Hello World Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-12-23 02:36 +0000
                Re: Hello World Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-12-23 12:24 -0500
              Re: Hello World Chris Angelico <rosuav@gmail.com> - 2014-12-23 12:03 +1100
          Encryption - was Hello World Dave Angel <d@davea.name> - 2014-12-22 14:57 -0500
          Re: Encryption - was Hello World Chris Angelico <rosuav@gmail.com> - 2014-12-23 09:29 +1100
          Re: Encryption - was Hello World Dave Angel <davea@davea.name> - 2014-12-22 18:22 -0500
      Re: Hello World Rustom Mody <rustompmody@gmail.com> - 2014-12-21 18:37 -0800
      Re: Hello World Steve Hayes <hayesstw@telkomsa.net> - 2014-12-22 08:21 +0200
        Re: Hello World Chris Angelico <rosuav@gmail.com> - 2014-12-22 17:33 +1100
          Re: Hello World Steve Hayes <hayesstw@telkomsa.net> - 2014-12-22 09:46 +0200
            Re: Hello World Chris Angelico <rosuav@gmail.com> - 2014-12-22 18:56 +1100
        Re: Hello World Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-22 20:18 +1100
          Re: Hello World Marko Rauhamaa <marko@pacujo.net> - 2014-12-22 11:34 +0200
            Re: Hello World Rustom Mody <rustompmody@gmail.com> - 2014-12-22 19:38 -0800
          Re: Hello World Roy Smith <roy@panix.com> - 2014-12-22 08:15 -0500
            Re: Hello World Chris Angelico <rosuav@gmail.com> - 2014-12-23 00:23 +1100
              OFF TOPIC Snow Crash [was Re: Hello World] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-23 13:09 +1100
                Re: OFF TOPIC Snow Crash [was Re: Hello World] Grant Edwards <invalid@invalid.invalid> - 2014-12-23 16:20 +0000
                Re: OFF TOPIC Snow Crash [was Re: Hello World] Rustom Mody <rustompmody@gmail.com> - 2014-12-23 08:41 -0800
                Re: OFF TOPIC Snow Crash [was Re: Hello World] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-24 12:51 +1100
                Re: OFF TOPIC Snow Crash [was Re: Hello World] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-24 14:18 +1100
                Re: OFF TOPIC Snow Crash [was Re: Hello World] alister <alister.nospam.ware@ntlworld.com> - 2014-12-24 11:50 +0000
                Re: OFF TOPIC Snow Crash [was Re: Hello World] alex23 <wuwei23@gmail.com> - 2014-12-26 09:34 +1000
                Re: OFF TOPIC Snow Crash [was Re: Hello World] alex23 <wuwei23@gmail.com> - 2014-12-26 09:27 +1000
                Re: OFF TOPIC Snow Crash [was Re: Hello World] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-26 15:13 +1100
                Re: OFF TOPIC Snow Crash [was Re: Hello World] alister <alister.nospam.ware@ntlworld.com> - 2014-12-26 10:03 +0000
            Re: Hello World Marko Rauhamaa <marko@pacujo.net> - 2014-12-22 15:26 +0200
              Re: Hello World Roy Smith <roy@panix.com> - 2014-12-22 08:41 -0500
        Re: Hello World Roy Smith <roy@panix.com> - 2014-12-22 08:13 -0500
          Re: Hello World Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-23 02:22 +1100
            Re: Hello World Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2014-12-22 17:36 +0200
              Re: Hello World Chris Warrick <kwpolska@gmail.com> - 2014-12-22 17:03 +0100
            Re: Hello World Skip Montanaro <skip.montanaro@gmail.com> - 2014-12-22 09:39 -0600
              Re: Hello World Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-23 03:54 +1100
            Re: Hello World Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-12-22 18:48 +0000
        Re: Hello World Grant Edwards <invalid@invalid.invalid> - 2014-12-22 16:26 +0000
    Re: Hello World Grant Edwards <invalid@invalid.invalid> - 2014-12-22 16:18 +0000
      Re: Hello World alister <alister.nospam.ware@ntlworld.com> - 2014-12-22 19:05 +0000

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