Format and link fix 2006/grothe/README.md
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# Most Obfuscaed Audio
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# Most Obfuscated Audio
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Aaron Grothe
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2205 South 51st Street
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Omaha, NE 68106
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US
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Aaron Grothe
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US
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## To build:
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@@ -43,86 +41,105 @@ feature to this entry. :-)
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## Selected Author's Comments:
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The program draws patterns on the screen that can be picked up by a
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shortwave radio. It emulates the frequencies for an old fashion touch
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tone phone, so old songs can be played by hitting 0-9,#, and *.
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[shortwave radio](https://en.wikipedia.org/wiki/Shortwave_radio). It emulates
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the frequencies for an old fashion touch tone phone, so old songs can be played
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by hitting `0-9`,`#`, and `*`.
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To be able to run the program you need to determine the following
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parameters
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parameters:
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carrier_freq - base frequency used to host music
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pixelclock - refresh rate of the monitor
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horizontal_total - total scan along the horizontal axis
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```
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carrier_freq - base frequency used to host music
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pixelclock - refresh rate of the monitor
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horizontal_total - total scan along the horizontal axis
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```
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If you have xvidtune installed you can get the pixelclock and
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horizontal total with the following command
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If you have `xvidtune` installed you can get the `pixelclock` and
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`horizontal_total` with the following command
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xvidtune -show | head -n 1 |
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awk '{ print "pixelclock " $2 * 1000000 " horizontal_total = " $6 }'
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```sh
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xvidtune -show | head -n 1 | awk '{ print "pixelclock " $2 * 1000000 " horizontal_total = " $6 }'
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```
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example from my laptops
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Example from my laptops:
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./grothe 65000000 10000000 1344 < twinkle.txt
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```sh
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./grothe 65000000 10000000 1344 < twinkle.txt
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```
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Even if the user gets a setting off, the sound will usually be able to be
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heard on AM at a multiple of the original frequency
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heard on [AM](https://en.wikipedia.org/wiki/AM_broadcasting) at a multiple of
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the original frequency.
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The core idea of using a machine to play music on AM radio goes all the
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way back to the Altair computers and Timex Sinclair ZX-81s.
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way back to the [Altair computers](https://en.wikipedia.org/wiki/Altair_8800)
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and [Timex Sinclair ZX-81](https://en.wikipedia.org/wiki/ZX81)s.
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### Several example songs
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Olympic Fanfare - from antang@phakt.usc.edu - Tony
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Olympic Fanfare - from `antang@phakt.usc.edu` - Tony:
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```
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4-9-91231,2222-321123123-9-91231,2222-32112321
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```
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Twinkle Twinkle Little Star - from fsufunkyb@aol.com - Ben Schmidt
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Twinkle Twinkle Little Star - from `fsufunkyb@aol.com` - Ben Schmidt:
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```
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1199##9-6633221-9966332-9966332-1199#9-6633221-
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```
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Generic Arabian Tune - from rdippold@qualcomm.com -Ron "Asbestos" Dippold
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Generic Arabian Tune - from `rdippold@qualcomm.com` - Ron "Asbestos" Dippold:
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```
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453,54,4569564459,9#95458,8987453 54
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```
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Others can be found by doing a search for "touch tone phone songs".
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### Obfuscations
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- Some numbers expressed in Octal, some in hex and some in decimal
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"A foolish consistency is the hobgoblin of little minds" -
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Ralph Waldo Emerson
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- Funky scoping, looking at the nanosleep section and
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XsetWindowAttributes declares local variables
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- Algorithm is very weird, uses y dimension to draw carrier frequency
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and x dimension to draw audio frequency, based on Erik Thiele's
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Tempest for Eliza
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- lack of #defines confuses many people :-)
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- figuring out your pixelclock and horizontal total and which carrier
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frequency to use can be an exercise in obfuscation for the user
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- use of commas in various places, confuses most c code beautifiers
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"A foolish consistency is the hobgoblin of little minds" - Ralph Waldo
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Emerson.
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- Funky scoping, looking at the nanosleep section and `XsetWindowAttributes`
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declares local variables.
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- Algorithm is very weird, uses `y` dimension to draw carrier frequency
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and `x` dimension to draw audio frequency, based on [Erik
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Thiele](http://www.erikyyy.de)'s
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[Tempest for Eliza](http://www.erikyyy.de/tempest/).
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- lack of `#define`s confuses many people :-)
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- figuring out your `pixelclock` and `horizontal_total` and which `carrier_freq`
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to use can be an exercise in obfuscation for the user.
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- use of commas in various places, confuses most C code beautifiers
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sometimes making the beautified code harder to read
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- use of static to ensure initilization is EVIL and done in several
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- use of `static` to ensure initialization is EVIL and done in several
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places
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- uses static declarations & voids function returns we don't care about
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making the code harder to read
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- does sound using only X11 libs, no other libs required
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- demonstrates tempest emissions in a fun/easy way
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- follows good programming practices of actually setting exit codes and
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giving usage when run with incorrect parameters
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- uses `static` declarations & `void` function returns we don't care about
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making the code harder to read.
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- does sound using only [X11 libs](https://en.wikipedia.org/wiki/Xlib), no other
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libs required.
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- demonstrates tempest emissions in a fun/easy way.
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- follows good programming practices of actually setting exit codes and giving
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usage when run with incorrect parameters.
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### References
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Tempest for Eliza - Basis for Algorithms
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[Tempest for Eliza - Basis for Algorithms](http://www.erikyyy.de/tempest/).
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> <http://www.erikyyy.de/tempest/>
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[Tempest
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AM](https://web.archive.org/web/20070612152538if_/http://silcnet.org/priikone/programs/tempest-AM-1.0.tar.gz)
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\- Another early program in this field. See
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[here](https://web.archive.org/web/20070612152538/http://silcnet.org/priikone/programs.php?lang=en)
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for a bit more information on the program (search for `Tempest-AM Radio Signal
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Transmitter`).
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Tempest AM - Another early program in this field
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The paper
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[Soft Tempest: Hidden Data Transmission Using Electromagnetic
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Emanations](https://www.cl.cam.ac.uk/~mgk25/ih98-tempest.pdf) by Markus G.
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Kuhn's and Ross J. Anderson's.
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> <http://silcnet.org/priikone/programs.php?lang=en>
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Paper by Markus G. Kuhn's and Ross J. Anderson's,
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"Soft Tempest: Hidden Data Transmission Using Electromagnetic Emanations"
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> <http://www.cl.cam.ac.uk/~mgk25/ih98-tempest.pdf>
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## Copyright and CC BY-SA 4.0 License:
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