Alex Smith wrote:
> I informally request comex and coppro to explain the answers to eir own
> puzzles (or to resubmit them if they prefer);
I will resubmit a modified version.
> I also informally request
> coppro to explain eir reasoning on READ ME, because IMO it's more
> interesting to hear the reasoning from a contestant than from the
> author. (Note that there's nothing in the rules of Enigma saying that
> this has to be done, though.)
Alright. The first thing I noticed was that these were probably
encodings of some form. Morse code and Base 64 I immediately decoded. I
next tackled the large block, which I guessed (correctly) might be a
punchcard for an old mainframe. I couldn't find a decoder until after
the contest ended, discovering /usr/games/bcd, so I used an online
encoder to find the answer with trial and error.
I tackled the greek next, initially trying to transliterate the letters,
discovering in the process that it was phonetic, and using that instead.
The first set I decoded as ascii, and then I spent quite some time on
the next three. After some sleuthing, I noticed the fourth set was UTF-8
- now I realize the c3 should give it away.
I spent some time on the other two. I guessed EBCDIC and Baudot, since
those were the only two reasonably-commong 8- and 5-bit encodings I'd
expect to see, but neither seemed to fit. It was comex who gave me the
clue I needed - that the second entry was in fact EBCDIC with every
second byte swapped (this was why I gave you all the answer, as I'll
explain). After a lot of research, I discovered the third one was in
fact Baudot (the INTERCAL variety, I believe) with the bytes swapped -
the tricky bit here is that you can't simply swap the cleartext, as
Baudot is a modal encoding.
I got the following:
{{
Start with the number 105.
Multiply that number by 91.
then, subtract 8.
Raise the result so far to the power of 5.
then subtract 123456, then add 8.
TAKE THE LAST 7 DIGITS OF YOUR RESULT SO FAR.
Subtract 1 from each digit of that result.
submit this number riten backwards as you anser
}}
which should be clear enough, but I discovered that the last two
instructions were ambiguous as to what happens with zeroes. I submitted
my four possible answers to ais523. I then rechecked and saw that I'd
forgotten to swap the 91 to a 19 in the second line, so I resubmitted my
answer, this time publicly.
Oops, and you're welcome.
