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belong to us
Posted: Fri Mar 27, 2009 11:48 pm
by MagneticMonopole
My solution:
Code: Select all
8c8c67*C1c67*1+C528**C8c9c67*C4c67*1+C528**C8c9c67*C4c67*1+C528**C8c4c67*C528**C
9c9c67*C8c67*1+C528**C9c8c67*C7c67*1+C528**C9c9c67*C4c67*1+C528**C9c9c67*C1c67*1+C528**C
8c4c67*C528**C8c8c67*C2c67*1+C528**C8c8c67*C1c67*1+C528**C9c9c67*C2c67*1+C528**C8c8c67*C
5c67*1+C528**C
Far from lightweight or elegant. I did not venture to decipher the symbols beyond "print number" and "print ascii".
Having the emulator run a second time over the output of the first round is either genius or madness. At the very least, I take the liberty to consider it ... unfriendly.
Btw, there was an obfuscator involved? I used both jad and jode, still getting rather unusual method names, which even a mere disassembler confirmed.[/code]
Posted: Sun Mar 29, 2009 1:16 am
by adum
yeah, i used my favorite obfuscator which really smacks java bytecode pretty hard.
Posted: Wed Nov 11, 2009 12:39 pm
by michuber
Finally I found
http://www.reversed-java.com which decompiles much better than JD.
So finding the differences to HVM was much easier.
Unfortunately it fails on "Protected Password 4", by now
Posted: Thu Jan 07, 2010 1:24 pm
by Icho
The class file accepts the following String:
Code: Select all
88*5+258**C99*2+258**C88*1+258**C88*2+258**C84*258**C99*1+258**C99*4+258**C99*2-258**C99*8+258**C84*258**C89*4+258**C89*4+258**C88*1+258**C
The online checker doesn't. Is that intended or a bug?
Posted: Mon Jan 11, 2010 8:40 pm
by nighthalk
all this thing is is the HVM interpreter which on the first pass swaps +13/-13 a - m with n - z, and all the opcodes are interpereted with a -12 base. but thats just to obscuferate what it does. i did however notice batch files HATE the ^ key (which my first elegant attempt was, then i did the unclean 1 letter at a time approach
Icho's code
Posted: Sat Jan 16, 2010 3:32 am
by tails
Aha, that seems to be a bug :-)
The Java class doesn't clear the stack before the second run. The code set up the data on the stack in the first run, and uses them in the second run. How neat :-) Maybe the online checker doesn't allow this?
Posted: Sat Dec 10, 2011 5:58 pm
by swgr
Very interesting challenge.
At first I do some fixing work for the obscured decompile code to make it clearer. And then I suddenly realize ( actually, guess ) that a(String, String, boolean) is a HVM interpreter when I see the long ( and broken ) switch list. Luckily this is correct.
By the way, HVM code length limitation in this challenge is also sick.. >_<
Here is my solution:
Code: Select all
99*19*+4+89*8+49*7+49*6+7c9c0^C2c1^C2^C8c9c0^C4c1^C0c3^C2^C2^C4c8c0^C0c3^C2^C9c9c0^C8c1^C2^C8c9c0^C7c1^C2^C9c9c0^C4c1^C2^C9c9c0^C1c1^C2^C2^C7c9c0^C3c1^C2^C7c9c0^C2c1^C2^C9c9c0^C2c1^C2^C7c9c0^C6c1^C2^C
Posted: Tue Feb 14, 2012 5:30 pm
by MatRush
Byte code is abstruse...
Does there any good java-decompiler?
Posted: Tue Dec 18, 2012 8:29 pm
by Redford
There are only a few decompilers, the best is DJ Java Decomp, but it has ugly and strange gui, and it's commercial. And it's only decompiler, not deobfuscator. Also, I used JavaDeObfuscator, but it only can rename methods and fields, nothing more.
Does anyone knows what "Emyoolay" means?
Nice task, adum
Posted: Thu Dec 20, 2012 9:20 pm
by laz0r
I think "Emyoolay" is a pun on "emulate", and possibly a slight hint towards the three-letter "HVM" - there might be a deeper meaning, though!
Posted: Sun May 11, 2014 11:10 am
by Hippo
At first I tought the double HVM call is a wrongly decompiled code
but using third decompiler shown the truth
jode did rather well.
I didn't notice the HVM does not clear stack so I used purely HVM solution. Requiring just two ROT13 swaps.