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[Reason]

[PUZZLE] #251 - Silver - The Thirteenth Labour

[SteveC]

The code is almost certainly RC5-64... Unless someone has a key (which I might, I'll update soon), it took the folks at www.distributed.net a few years to do this one.

[Reason]

When Fi saw me get this one out the pack she told me it should be solved 'sooner rather than later'. Its lost on me I'm afraid though. Six digits at the top seem like they could be refering to a date, possible live meet or broadcast?

[BennyH]

On the 64th of December? Unless the dates are Perplexian, or some such silliness...

I don't believe that the CRP would want us to spend two years on a card...so maybe it appears to be an advanced cipher, when in fact that isn't how we should be looking at it?

I say this only because I am a maths retard, and don't want to be left out.

[Reason]

I didn't mean that we would take the date literally, I was thinking along the lines they we had to decifer it first.

[Atrophied]

I've transcribed the code for you.

Enjoy.

[cassandra]

More large gray letter parts (see the purple 'in other words' or whatever it is) - perhaps soon we'll be able to get another message via the card vertices lining up?

[Enigmaster]

Hmm, the name is very interesting. It was just last week that the 12 labours of hercules were compared to a perplexian equivelent, and now we're seeing it again.
But a thirteenth labour...? I dunno, maybe my research just isn't up to scratch.

[Atrophied]

From Steve C (IRC)

There are currently 12 RC5 challenges posted by RSA security, this would be a thirteenth challenge.

the cows link to www.distributed.net (5 pointing to RC5 possibly)

[Enigmaster]

[Mosestrotsky]

Hi,

Now I know I won't be able to solve this one but can you guys explain what RC5-64 code is in very simple terms as I have no idea.

Also could the date be reversed?

8th December 264 Perplexian time or is that numer part of the code?

[JebJoya]

Umm, by a very brief calculation, if everyone's running Athlon 64 3200+ (my computer), it would take 142,000 computer-years of runtime. Ouch.

Jeb

[Axys Denyed]

The 64/12/8 refers to the particulars of the RC5 encryption. It basically means it has 64-bit wordsize, 12 rounds and 8*8=64bit encryption

[SteveC]

Just to catch anyone up who's floundering....

rc5 is a very heavy encryption protocol that's used internationally. The little cows on the picture are a direct reference to the nice folks (well, mostly nice) at www.distributed.net. The bits I can understand of the code are as follows:

the 64/12/8 is notation to tell you the parametrs used to encode.. It's a block size of 64 bits (as it 64 ones and zeros are processed at a time), you pass over it 12 times and the "key" used is 8 bytes (64 bits making it an rc5-64) long.

The five cows could be a reference to ingrain that it's RC5 as well as pointing us to them.

Now, to decrypt this, you need a few more things..

1/ software to decrypt
2/ an IV (initial vector) which are the initial starting values of the system.
3/ a key - the machine readable password

1/ I don't have

2/ We might have, but I'm not sure if because this is 64 bit it'll be more difficult to achieve. At a guess, it's possibly using the RC5-64 IV mentioned on http://www.rsasecurity.com/rsalabs/node.asp?id=2106

3/ my only guess is to use the same key (0x63DE7DC154F4D039) as www.distributed.net used.

Thanks to Nerf who's a distributed hanger on-er for help with some of this..

[Seej]

More shaded bits on this at the top and bottom that look like they're part of large letters extending onto other cards, just like I mention in this thread.

EDIT: Oops, cassandra mentioned this too