Re: Embedding a Checksum in an Image File

From	David Brown <david.brown@hesbynett.no>
Newsgroups	comp.arch.embedded
Subject	Re: Embedding a Checksum in an Image File
Date	2023-04-28 09:38 +0200
Organization	A noiseless patient Spider
Message-ID	<u2ft59$2bnd0$4@dont-email.me> (permalink)
References	<116ff07e-5e25-469a-90a0-9474108aadd3n@googlegroups.com> <105b1cab-9e5f-91b3-1de6-99586246ecbd@gmail.com> <b62a77f7-3a13-4d76-b7cb-c42902595751n@googlegroups.com> <kavt7iFlvc5U1@mid.individual.net> <u2emsa$22pgk$2@dont-email.me>

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On 27/04/2023 22:44, Ulf Samuelsson wrote:
> Den 2023-04-27 kl. 20:29, skrev Niklas Holsti:
>> On 2023-04-27 20:09, Rick C wrote:

> 
>>
>>> You are making a lot of assumptions about the tools.  I'm pretty sure
>>> they don't apply to my case.  I'm not at all clear how this is
>>> workable, anyway.  Adding the checksum to the file, changes the
>>> checksum, which is where this conversation started... unless I'm
>>> missing something significant.
> No, you reserve room for the checksum, but that needs to be outside
> the checked area.
> The address of the checksum needs to be known to the application.

The address here could have a symbol, and then declared "extern" in the 
C code - it would not have to be a known numerical address.  But if the 
image is checked or started from another program (such as a boot 
program), you need an absolute address somewhere to chain this all together.

> Also the limits of the checked area.
> That is why the application has a header in front in my projects.
> The application is started by the bootloader, which checks
> a number of things before the application is started.
> The application can read the header as well to allow checking
> the code area at runtime.
> 

Or for my preferences, the CRC "DIGEST" would be put at the end of the 
image, rather than near the start.  Then the "from, to" range would 
cover the entire image except for the final CRC.  But I'd have a similar 
directive for the length of the image at a specific area near the start.

Thread

Embedding a Checksum in an Image File Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-19 19:06 -0700
  Re: Embedding a Checksum in an Image File Niklas Holsti <niklas.holsti@tidorum.invalid> - 2023-04-20 12:14 +0300
    Re: Embedding a Checksum in an Image File Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-20 06:18 -0700
  Re: Embedding a Checksum in an Image File "Peter Heitzer" <peter.heitzer@rz.uni-regensburg.de> - 2023-04-20 11:30 +0000
  Re: Embedding a Checksum in an Image File dalai lamah <antonio12358@hotmail.com> - 2023-04-20 13:47 +0200
    Re: Embedding a Checksum in an Image File Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-20 06:04 -0700
  Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-20 16:46 +0200
  Re: Embedding a Checksum in an Image File George Neuner <gneuner2@comcast.net> - 2023-04-20 11:33 -0400
    Re: Embedding a Checksum in an Image File Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-20 09:45 -0700
      Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-20 22:26 +0200
        Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-27 18:36 +0200
          Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-28 09:12 +0200
            Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-28 10:35 +0200
      Re: Embedding a Checksum in an Image File George Neuner <gneuner2@comcast.net> - 2023-04-20 16:44 -0400
        Re: Embedding a Checksum in an Image File Don Y <blockedofcourse@foo.invalid> - 2023-04-20 22:37 -0700
          Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-21 12:43 +0200
            Re: Embedding a Checksum in an Image File Don Y <blockedofcourse@foo.invalid> - 2023-04-21 04:39 -0700
              Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-21 16:50 +0200
                Re: Embedding a Checksum in an Image File Don Y <blockedofcourse@foo.invalid> - 2023-04-21 17:29 -0700
                Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-22 16:57 +0200
                Re: Embedding a Checksum in an Image File Don Y <blockedofcourse@foo.invalid> - 2023-04-24 00:32 -0700
                Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-24 16:37 +0200
                Re: Embedding a Checksum in an Image File Don Y <blockedofcourse@foo.invalid> - 2023-05-03 00:15 -0700
                Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-05-03 14:48 +0200
                Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-05-09 20:42 +0200
                Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-05-10 10:06 +0200
                Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-05-10 12:03 +0200
                Re: Embedding a Checksum in an Image File Don Y <blockedofcourse@foo.invalid> - 2023-08-05 01:48 -0700
                Re: Embedding a Checksum in an Image File Don Y <blockedofcourse@foo.invalid> - 2023-08-05 01:42 -0700
        Re: Embedding a Checksum in an Image File Stefan Reuther <stefan.news@arcor.de> - 2023-04-21 19:40 +0200
    Re: Embedding a Checksum in an Image File Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2023-04-20 20:17 +0300
      Re: Embedding a Checksum in an Image File George Neuner <gneuner2@comcast.net> - 2023-04-20 16:49 -0400
  Re: Embedding a Checksum in an Image File Richard Damon <Richard@Damon-Family.org> - 2023-04-20 22:09 -0400
    Re: Embedding a Checksum in an Image File Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-20 19:41 -0700
      Re: Embedding a Checksum in an Image File Richard Damon <Richard@Damon-Family.org> - 2023-04-21 19:30 -0400
  Re: Embedding a Checksum in an Image File Brian Cockburn <brian.cockburn.1959@gmail.com> - 2023-04-21 01:53 -0700
    Re: Embedding a Checksum in an Image File Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-21 05:12 -0700
      Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-21 17:02 +0200
        Re: Embedding a Checksum in an Image File Brian Cockburn <brian.cockburn.1959@gmail.com> - 2023-04-21 16:56 -0700
          Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-22 17:01 +0200
        Re: Embedding a Checksum in an Image File Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-21 20:14 -0700
          Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-22 17:13 +0200
            Re: Embedding a Checksum in an Image File Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-22 09:56 -0700
              Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-22 19:54 +0200
                Re: Embedding a Checksum in an Image File Grant Edwards <invalid@invalid.invalid> - 2023-04-22 20:05 +0000
                Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-23 17:37 +0200
                Re: Embedding a Checksum in an Image File Grant Edwards <invalid@invalid.invalid> - 2023-04-23 17:37 +0000
                Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-23 23:45 +0200
                Re: Embedding a Checksum in an Image File Richard Damon <Richard@Damon-Family.org> - 2023-04-23 18:16 -0400
                Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-24 09:13 +0200
                Re: Embedding a Checksum in an Image File boB <boB@K7IQ.com> - 2023-04-22 13:41 -0700
                Re: Embedding a Checksum in an Image File Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-23 10:34 -0700
                Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-23 23:58 +0200
                Re: Embedding a Checksum in an Image File Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-23 15:24 -0700
                Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-24 09:17 +0200
                Re: Embedding a Checksum in an Image File Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-24 01:07 -0700
          Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-27 18:42 +0200
            Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-28 09:20 +0200
              Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-28 10:44 +0200
      Re: Embedding a Checksum in an Image File Brian Cockburn <brian.cockburn.1959@gmail.com> - 2023-04-21 16:52 -0700
        Re: Embedding a Checksum in an Image File Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-21 20:23 -0700
          Re: Embedding a Checksum in an Image File Brian Cockburn <brian.cockburn.1959@gmail.com> - 2023-04-22 07:07 -0700
            Re: Embedding a Checksum in an Image File Richard Damon <Richard@Damon-Family.org> - 2023-04-22 10:31 -0400
            Re: Embedding a Checksum in an Image File Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-22 09:54 -0700
  Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-27 18:26 +0200
    Re: Embedding a Checksum in an Image File Rick C <gnuarm.deletethisbit@gmail.com> - 2023-04-27 10:09 -0700
      Re: Embedding a Checksum in an Image File Niklas Holsti <niklas.holsti@tidorum.invalid> - 2023-04-27 21:29 +0300
        Re: Embedding a Checksum in an Image File Niklas Holsti <niklas.holsti@tidorum.invalid> - 2023-04-27 21:39 +0300
        Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-27 22:44 +0200
          Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-28 09:38 +0200
            Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-28 10:50 +0200
              Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-28 15:04 +0200
                Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-29 23:03 +0200
                Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-30 16:19 +0200
                Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-05-09 20:34 +0200
                Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-05-10 10:18 +0200
        Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-28 09:33 +0200
      Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-27 22:36 +0200
        Re: Embedding a Checksum in an Image File Niklas Holsti <niklas.holsti@tidorum.invalid> - 2023-04-28 01:10 +0300
          Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-28 10:54 +0200
    Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-28 09:24 +0200
      Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-28 10:56 +0200
        Re: Embedding a Checksum in an Image File David Brown <david.brown@hesbynett.no> - 2023-04-28 15:09 +0200
          Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-29 23:02 +0200
  Re: Embedding a Checksum in an Image File Ulf Samuelsson <ulf.r.samuelsson@gmail.com> - 2023-04-27 18:27 +0200

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