Landon Curt Noll
9f57052020
We rewrote the `bin/tar-entry.sh` algorithm so that we do NOT have to require Linux to produce a compressed tarball that is byte-for-byte identical to a macOS compressed tarball for the same entry. Changed `bin/tar-entry.sh` VERSION from "1.2 2024-03-22" to "1.3 2024-03-25". Added `bin/untar-entry.sh` to untar an entry from the compressed tarball. Added `make untar_entry_tarball` to untar all entry files. Added `make untar_year_tarball` and `make untar_all_tarball` stub Makefile rules. The core it referred to does not yet exist. Updated IOCCC manifest. Updated `.entry.json` for `2004/sds`. Performed `make www` to update web pages. In most cases the entry `index.html` added an inventory link for the new `.tar.tstamp` file. Performed `form_entry_tarball` to complete the test of the above. TODO: Test the results under Linux. TODO: Update `bin/tar-year.sh`. Update year level compressed tarballs. TODO: Update `bin/tar-all.sh`. Update top level compressed tarball. TODO: Write `bin/untar-year.sh` and `bin/untar-all.sh`.
136 lines
3.7 KiB
Plaintext
136 lines
3.7 KiB
Plaintext
# NOT AN OFFICIAL README
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NOTE: This is a copy of README.md as it was in 2024 Jan 15.
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For the official README see [README.md](README.md) or
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view [index.html](index.html).
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## To build:
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```sh
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make
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```
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### Bugs and (Mis)features:
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The current status of this entry is:
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```
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STATUS: INABIAF - please **DO NOT** fix
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```
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For more detailed information see [2004 sds bugs](../../bugs.html#2004_sds).
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## To use:
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```sh
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./sds
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```
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## Try:
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```sh
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./try.sh
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```
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## Judges' remarks:
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Why not use the program to hide another program in the program? It
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must have seemed reasonable at the time.
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The ability to hide a message in plain text is quite charming, really.
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We must admit to a bit of uncertainty about where you'd find such
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messages, or how useful they'd be. Or, of course, whether all those
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horribly badly formatted emails spammers send might contain secret
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messages. Annoyingly, it's a little too obvious that SOMETHING has
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been done to a message for us to hide one in the remarks. :)
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## Author's remarks:
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[Steganography](https://en.wikipedia.org/wiki/Steganography) is the term for the
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family of techniques used for hiding information within other information.
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Today, it has many real world uses, particularly for digital watermarking.
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This program uses a steganographic technique to hide information in any text
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file. The specific technique used is aimed at writers of obfuscated programs
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for the IOCCC, as the hidden information is encoded in the whitespace in the
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source file. As we know, there are up to an additional 2048 characters of
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whitespace available to entrants to the IOCCC, so it turns out that this is an
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ideal place to hide things.
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The program as provided is the steganographic decoder. Rather than
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provide a separate encoding program, you should not be surprised to
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learn that I opted to steganographically hide the encoder inside the
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decoder.
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Try it out. Compile the program, then type
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```sh
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./sds < sds.c
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```
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You should see the encoder program displayed. Now save it, like:
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```sh
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./sds < sds.c > encoder.c
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```
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Then compile `encoder.c`. You now have the complete system ready.
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The encoder expects to get a filename as an argument. This filename
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is the name of the file containing the information to be hidden. It
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expects the file in which to hide the information to be on the
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standard input, and will output the results on the standard output.
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You can use it like this (assuming you have a file called remarks):
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```sh
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echo 'Hello, World!' > message
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./encoder message < remarks > remarks_msg
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```
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Then to decode:
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```sh
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./sds < remarks_msg
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Hello, World!
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```
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C programs are mostly unaffected by adding steganographic content,
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but it is possible in certain circumstances for whitespace to be
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changed inside strings where it should be left alone. Plain text
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files are good candidates for hiding information in, but the added
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spacing may render the text somewhat difficult to read.
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### Obfuscation
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This program is obfuscated in a number of ways:
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* The code is all but impossible to read due to the spacing.
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* The algorithm is well hidden in the code due to copious red-herrings.
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* The long expressions cause indentation tools to give poor results.
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* And good old fashioned ternary operators are the icing on the cake.
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### Compiling the program
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The program (and the encoder program) should compile on any
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reasonable compiler. In particular, they are known to compile under
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GNU C.
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## Copyright and CC BY-SA 4.0 License:
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This file is Copyright (c) 2023 by Landon Curt Noll. All Rights Reserved.
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You are free to share and adapt this file under the terms of this license:
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Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
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For more information, see: https://creativecommons.org/licenses/by-sa/4.0/
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