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Cryptography Challenge #17!
Link | by gendou on 2007-07-09 09:03:56 (edited 2007-08-17 22:42:25)
Welcome to Gendou.com Cryptography Challenge #17!
The goal of this game is to decode the message.
Once you do this, send it to me in a forum message by clicking here.
If you decode it correctly, I will give you a level up and put your name on the scoreboard!
0 0 1536 512 1024 0 512 512 256 256 1280 1280 1792 768 768 1792 256 1280 1280 1280 1536 512 1536 1536 768 1792 1280 1280 512 1536 1536 1536 0 0 0 0 256 256 1792 768 0 0 0 1024 768 1792 1792 1792 448 448 960 960 1728 704 1216 1216 64 1088 576 1600 576 576 1600 1600 16 1040 16 16 1552 1552 1552 1552 784 784 272 272 528 528 1040 16 336 336 1872 848 1104 80 1616 1616 720 1744 208 1232 208 1232 1232 1232 80 1104 1104 80 848 1872 1360 1360 720 720 208 1232 208 1232 1232 1232 464 464 976 976 720 720 1232 208 208 1232 1744 720 1488 464 2000 2000 0 1024 512 1536 512 512 1536 1536 512 1536 0 1024 768 768 1792 1792 0 0 512 512 256 1280 1792 1792 768 768 256 256 768 768 1792 768 128 1152 1664 640 128 1152 1664 1664 0 1024 0 0 1536 512 1536 1536 128 128 1152 1152 1152 128 1152 1152 384 1408 1408 1408 640 640 1152 1152 96 1120 96 96 1120 96 1120 1120 480 480 2016 2016 1760 736 1760 1760 288 1312 1824 1824 32 32 1568 1568 288 288 288 288 800 800 1824 800 64 1088 576 576 1856 832 1856 1856 576 576 64 1088 832 1856 1856 1856 192 192 192 192 448 448 1472 448 448 448 960 1984 960 1984 1984 960 20 1044 20 1044 276 276 1812 1812 788 788 1300 1300 532 1556 1556 1556 84 1108 596 1620 340 340 1876 1876 468 468 1492 468 980 2004 2004 2004 52 52 52 52 52 52 1076 52 180 180 1204 180 1972 948 1460 1460 244 1268 756 1780 1012 2036 1524 1524 500 1524 2036 1012 1012 2036 2036 2036 4 4 4 1028 4 1028 1540 1540 4 4 516 516 516 516 1540 516 4 4 1540 516 4 4 1028 1028 260 1284 260 1284 516 516 1540 1540 68 1092 1092 68 836 836 1348 1348 324 1348 836 836 836 836 1860 1860 196 1220 196 1220 196 1220 1732 1732 324 1348 1860 836 836 1860 1860 1860 52 1076 564 1588 308 308 1844 1844 308 308 1332 1332 1844 820 1844 820 436 436 1460 1460 1204 180 1716 692 436 436 1460 1460 1972 948 1972 948 148 148 148 148 404 404 404 404 20 20 20 20 788 788 276 276 148 148 660 660 660 660 148 148 404 404 916 916 916 916 916 916 52 52 564 564 308 308 308 308 948 948 436 436 692 692 692 692 52 52 52 52 820 820 820 820 948 948 436 436 948 948 948 948 116 116 628 628 628 628 628 628 116 116 116 116 628 628 628 628 180 180 692 692 180 180 180 180 948 948 436 436 692 692 692 692 10 10 10 10 778 778 778 778 778 778 266 266 778 778 778 778 458 458 970 970 714 714 714 714 458 458 458 458 970 970 970 970 106 106 106 106 106 106 106 106 490 490 490 490 1002 1002 490 490 426 426 938 938 170 170 170 170 938 938 426 426 938 938 938 938 58 58 58 58 58 58 570 570 186 186 698 698 698 698 698 698 122 122 122 122 122 122 634 634 1018 1018 506 506 762 762 250 250 90 90 90 90 346 346 346 346 90 90 90 90 602 602 90 90 218 218 218 218 730 730 730 730 986 986 474 474 986 986 986 986 18 18 530 530 530 530 530 530 786 786 274 274 786 786 786 786 466 466 466 466 210 210 722 722 338 338 850 850 850 850 850 850 114 114 114 114 114 114 114 114 242 242 242 242 1010 1010 498 498 242 242 754 754 754 754 242 242 1010 1010 498 498 1010 1010 1010 1010 98 98 98 98 610 610 610 610 610 610 98 98 610 610 610 610 34 34 546 546 546 546 546 546 802 802 290 290 546 546 546 546 98 98 610 610 866 866 866 866 354 354 866 866 866 866 866 866 482 482 994 994 226 226 226 226 866 866 354 354 866 866 866 866 14 14 14 14 526 526 526 526 910 910 398 398 910 910 910 910 270 270 782 782 526 526 526 526 398 398 398 398 910 910 910 910 78 78 78 78 78 78 78 78 78 78 78 78 590 590 78 78 206 206 718 718 718 718 718 718 462 462 974 974 718 718 718 718 94 94 94 94 350 350 350 350 606 606 94 94 862 862 862 862 414 414 926 926 158 158 158 158 414 414 414 414 926 926 926 926 222 222 222 222 478 478 990 990 94 94 606 606 606 606 606 606 478 478 478 478 478 478 478 478 478 478 478 478 990 990 478 478 30 30 542 542 30 30 30 30 542 542 30 30 542 542 542 542 94 94 94 94 94 94 606 606 478 478 990 990 734 734 734 734 94 94 94 94 94 94 94 94 350 350 350 350 862 862 350 350 222 222 734 734 734 734 734 734 478 478 990 990 990 990 990 990 62 62 574 574 62 62 62 62 446 446 446 446 702 702 702 702 190 190 702 702 958 958 446 446 318 318 830 830 830 830 830 830 94 94 94 94 862 862 862 862 734 734 222 222 734 734 222 222 478 478 990 990 222 222 734 734 990 990 478 478 478 478 478 478
hint 1
hint 2
hint 3
hint 4
hint 5

Scoreboard:


Re: Cryptography Challenge #17!
Link | by meow on 2007-07-09 22:13:03
I thought I knew how to do it 'till I looked at hint 4&5. Now I am totally lost. Ugh. I can't wait to see what it says. By the way, did you put the answer to the Cryptography Challenger #13 yet? I didn't see it and was interested in the answer.

Re: Cryptography Challenge #17!
Link | by Natzor on 2007-07-10 15:59:10 (edited 2007-07-10 16:22:10)
99% chance that we will need to do some binary editing to get this cracked. I'm seeing 2 patterns...
1. The last 4-5 bits show consistancy over long ranges
2. ... it's hard to explain.

http://darknovagames.com/w17.txt

and some binary dumps of the examples
a - length: 8
b - length: 8
c - length: 8
abc - length: 16
ab - length: 16

Cheers!

Re: Cryptography Challenge #17!
Link | by gendou on 2007-07-10 16:22:01 (edited 2007-07-10 16:24:38)
correction: "a", "b", and "c" (all one character long) produce an 8-number encoded output. you had put 10. try turning the binary output 90°


Re: Cryptography Challenge #17!
Link | by Natzor on 2007-07-10 16:54:43 (edited 2007-07-10 16:56:36)
my bad. and yeah, I was thinking something like that, gendou :) thats a pretty big hint, though...

but can you give me an equation, or at least the variable that determines the length of the output?

Re: Cryptography Challenge #17!
Link | by gendou on 2007-07-10 18:26:10 (edited 2007-07-11 11:35:02)
the number of elements in the encoded message is equal to the first member of the sequence 2n-1 in which the number of bits in the plain text message will NOT fit.


Re: Cryptography Challenge #17!
Link | by Natzor on 2007-07-11 07:13:32
In english, gendou says:
The lowest possible result that is equal to or larger than the number of characters in the message that can be generated by 2^(n-1) is used, where n is a positive integer. [the 2^(n-1) sequence refers to this: 0,1,2,4,8,16,...]

The message length is less than 2048 characters long, but at least 1024 characters long.

Trying to solve the relation between a, b, and ab...

a1_|_ b2
A5 | B4

a
a
a
a
A+B
A+B
A-B / a
A-B / a
[-8]+b
[-9]+b
[-10]+b
[-11]+b
[-6]+B
[-7]+B
[-8]+B
[-9]+B

There too many possibilities, and it's not like I can brute force it like gendou did to mine... don't have the time or cpu power to do it.

Re: Cryptography Challenge #17!
Link | by gendou on 2007-07-11 11:26:14 (edited 2007-07-11 11:53:16)
There is an elegant solution that is non-trivial (brute force will not work), and CAN be deduced logically from the pattern in the bits you printed in w17.txt

I will grant that the decoded message is 177 bytes long.
177 * 8 = 1,416 bits
1416 is between 211-1 and 210-1 so we choose the lower of the two
that makes 1024 elements in the decoded message

funny, how we don't choose the higher of the two?
where do you think those extra 392 get stuffed into?


Re: Cryptography Challenge #17!
Link | by on 2007-07-11 16:38:12
this is wawy too much math and thinking for me hopefully the next on ewill be easier

Forward, Go!

Re: Cryptography Challenge #17!
Link | by gendou on 2007-07-11 18:22:07
its really not that much math. the tricky part is seeing patterns, not knowing powers of 2.


Re: Cryptography Challenge #17!
Link | by GNOMEEATER on 2007-07-12 02:45:20
Oh crud. I understand it, but it's more work than I'm willing to do. (Some people like a challenge, not me) If I have time between classes, I'll do it and see if I'm right.


Re: Cryptography Challenge #17!
Link | by Raccool on 2007-07-12 23:40:08
I don't know... scrolling through the text file, looking at only the binary, and letting my eyes slide out of focus, it almost looks like a... what're those called.... when you have audio and you have the s... the wave.. it kind of looks like that but piecing together something like that is far beyond my capabilities. Then again, I could be way off. Probably the more likely.

Re: Cryptography Challenge #17!
Link | by blitz_d1 on 2007-07-12 23:55:20
-_-....wat the hell...wat am i suppose to look for?

Re: Cryptography Challenge #17!
Link | by sake on 2007-07-13 20:21:38
Wow. Math at it's most confusing ever.

Where's MY cup noodle dammit?!

Re: Cryptography Challenge #17!
Link | by on 2007-07-13 20:34:01
Some previous challenges are actually more confusing. (Not saying that this is not confusing at all, though)
I think I can understand if I try to, but I'm currently too lazy to try to solve it...


Re: Cryptography Challenge #17!
Link | by meow on 2007-07-18 14:38:42 (edited 2007-07-19 12:34:07)
Whoa, I was looking at this and I could see letters in the spaces between the numbers. . .

I know I saw a W, and at first it looked like it said WHY at the top.

Re: Cryptography Challenge #17!
Link | by gendou on 2007-07-18 15:19:49
I'm surprised nobody has figured this one out yet.


Re: Cryptography Challenge #17!
Link | by Jiraiya is here on 2007-07-19 15:23:26
please, give a clue, gendou.

Rasengan

Re: Cryptography Challenge #17!
Link | by gendou on 2007-07-19 16:15:30 (edited 2007-07-20 21:58:46)
Look at w17a.txt and w17ab.txt side by side. Notice that the ones place is solid 1s for both. Notice that the fours place is half 1s for both. This is not coincidence, it is correspondence. Starting from size 1, the message "expands" by a factor of 2 every time it "runs out of room" to store the next bit.

[EDIT] Congratulations to cauchy for being the first user to finish the challenge!


Re: Cryptography Challenge #17!
Link | by Cauchy on 2007-07-20 23:08:57 (edited 2007-07-20 23:12:01)
That was quite a hassle. I'm not a programmer, so after I figured out how the information was encoded, I used the w17.txt file and a second Notepad file to transcribe the 1440 bits of information into a line, and then turned that into the text.

Also, the message is 180 bytes long, gendou, though three of the bytes don't show up in the message, so I can see why you wrote 177.

Despite being a hassle, this was still quite fun. I really enjoy puzzles like these. I always forget to search for new Challenges, so I really like it when you link them on the main page.

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