## To build: ``` make all ``` There is an Alternate version which is what was originally published. See [Alternate code](#alternate-code) below for more information. ## To use: ``` ./nathan # enter some text ``` ## Try: To see some other fun uses: ``` ./try.sh ``` ## Alternate code: At the time of publication, the judges could not publish the code due to the US export control over encryption. The code that was published would, if run, allow one to get the instructions of how to receive (via email) the actual entry. However, on Sat Mar 4 20:09:35 2023 UTC, the previously unseen code was published. This meant that the old code was not set to compile via the Makefile. This alternate code is that previous version. ## Alternate build: ``` make alt ``` ### Alternate use: ``` ./nathan.alt ``` **IMPORTANT NOTE**: it is unknown if the email in the code is still valid and as one does not need to email the author for the submitted code one should not email it. In other words, please do **NOT** send such an email. ## Judges' remarks: ### WARNING: The judges make no claim as to the strength or security of this program. It is likely to be nil, or the next best thing to it. Still, you might consider installing it in `/usr/games/nathan`. :-) ### Note from the judges about the winning category: The 'winning' category is also open to question. One could say that it is a 'file obfuscator'. One could also say that it unintentionally abused the intent of rule #7 (that programs should be freely re-distributable). We suspect that the author may not have intended to do this, but that is the way things go sometimes. BTW, '_abuse of the rules_' entries do not violate the rules. Entries that violate the rules are disqualified. Abuse of the rules entries are ones that tend to 'stretch' the limits and take the contest into unexpected territory. ### Historical notes from the judges about this entry: The US International Traffic in Arms Regulations controls certain exportations going out of the United States. The U.S. Munitions List gives the specific categories of restricted exports. Because this entry at one time appeared to fall under this restricted category, the judges originally were not able to distribute some winning entries outside of the US. Nathan Sidwell stated that he was willing to distribute the winning source. To read HIS instructions of how to obtain his winning program one was able to run: ``` make nathan ./nathan ``` to learn how to get a copy of the code. When someone compiled and ran the code as originally distributed (see: [nathan.orig.c](%%REPO_URL%%/1992/nathan/nathan.orig.c) the code printed the following message (sic): > Export of this program from the USA is governed by the US
> Munitions List from the ITAR (International Traffic in Arms
> Regulations). This list gives the specific categories of
> restricted exports and includes cryptographic exports. Traffic
> entirely external to, entirely internal to, or into the USA is
> not restricted.
> To obtain a copy of the program, email to __EMAIL_ADDRESS_OMITTED__
> with a subject "IOCCC request". If you know that your 'From'
> line is incorrect, add a single line
> "replyto you@your.correct.address" to the body of the message.
> A deamon will autoreply.
> WARNING: You must not re-export this out of the USA, or else
> the men in black might get you. Today, the [nathan.c](%%REPO_URL%%/1992/nathan/nathan.c) source code is the source code is what you would have received had you successfully completed the above instructions. Today, the above instructions are **no longer necessary**. There have been reproduced above to provide historical context. Even so, the [Alternate code](#alternate-code) allows you to see what the originally published code did. ### Personal note from chongo: I think the situation showed just how ridiculous US crypto regulations really were/are. Certain US federal officials can get away with shipping arms to certain nations in apparent violation of US laws, but I personally can't re-distribute a program contest entry to the network! ### Updated personal note from chongo: We removed the email address from the above quote (although you can still see it in the [nathan.orig.c](%%REPO_URL%%/1992/nathan/nathan.orig.c) and [nathan.alt.c](%%REPO_URL%%/1992/nathan/nathan.alt.c) code) because sending email to that address is not required today and it is unknown if it is still valid. The [nathan.c](%%REPO_URL%%/1992/nathan/nathan.c) file now contains the source you would have received in reply. Thankfully much of the ridiculous US crypto regulations has been amended to the extent where the above historical "_workaround_" is **no longer required**. ## Author's remarks: ### Program use This program is a hello world text encryptor/decryptor. It uses an enigma (I think) style encryption algorithm, where the encryption key character is modified by a value, determined from the previous character. Non-printable characters (those with ASCII values < `' '` or > `0x7e`) are passed unaltered, thus any kind of file may be successfully processed, but if the original is printable, the processed file will be too. The input is read from `stdin`, and the output presented to `stdout`. The key, a text string, is presented as a command argument. This is optional, and if omitted, the file is self-{de,en}crypted. To specify decryption, a `-` should be given before the key. (Actually encryption and decryption proper inverse operations, so you can use decrypt to scramble and encrypt to descramble, if you're perverse.) ### Portability (A little knowledge is a dangerous thing) It's written in ANSI C, and doesn't even assume an ASCII character set, (it has an array of the characters to convert), so should be portable across many platforms. It passes `gcc -ansi -pedantic -O -Wall` with no warnings (You may get assignment in conditional warnings on other platforms though). Because I've heard that conditional jumps slow down fast processors, I've eliminated all the `if`s from the code; indeed, as its only one statement, it should compile to one instruction and a suitably designed CISC machine. To speed compilation, there is only one statement in the loop, so that another scoping level does not need to be opened. Being an encryptor/decryptor, you probably want the source code to be obfuscated, to hide the algorithm. ### Obfuscation In spite of the fact that it looks like a nice friendly hello world program, it isn't (as documented above). (Short lines have been padded, as you'll find if you look at an encrypted copy of the source.) I've also named some of the macros from commonly used functions, just to keep things muddy. Of course, all the variables are misnamed. The program is kept simply (one for statement), by serious overuse of `,` and `?:`. These are really confusing when used together, nested or put in argument lists (is that a comma operator, or argument separator?).