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From: Ben Bacarisse <ben.usenet@bsb.me.uk>
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Subject: Re: GNAT.SHA256 produces result different from sha257sum on Linux
Date: Sat, 04 Nov 2023 17:53:34 +0000
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wvxvw <olegsivokon@gmail.com> writes:

> "Jeffrey R.Carter" <spam.jrcarter.not@spam.acm.org.not> writes:
>
>> I think the problem may be that echo adds an LF:
>>
>> $ echo foo | hd
>> 00000000  66 6f 6f 0a                                       |foo.|
>>
>> Since sha256sum expects to work on arbitrary files, it would include
>> the LF in its input.
>
> Hi, thanks for the idea, but no, that's not it.

You say that's not it, but with the newline removed, sha256sum gives the
same hash as your original test code:

$ printf foo | sha256sum -
2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae  -

>From your earlier post:
> Eg, with GNAT.SHA256 for string "foo" I get:
>
> ❯ ./bin/test_sha --arg foo
> 2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae

> With the line end added
> I get 04e1806fda6bdbc9e5e3534edd993c7c2bf03173f5489742db53d1e8b0ef8c61
> from Ada.

Ah!  You didn't add a newline!  I can get the same hash by guesswork:

$ printf foo\\\\n >input
$ sha256sum input
04e1806fda6bdbc9e5e3534edd993c7c2bf03173f5489742db53d1e8b0ef8c61  input
$ hd input
00000000  66 6f 6f 5c 6e                                    |foo\n|
00000005

What you added to the test string was a backslash and a letter n.

-- 
Ben.