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[Fun]/prog/ Challenge #-1764 [CompSci]

Name: Anonymous 2013-07-03 2:47

How many iterations of the MD5 algorithm, performed on the hash emitted by the previous hashing, and using an arbitrary initial string, would be needed for the sum to begin to loop over past values?

Prizes:
Participation ribbon: Worst case time.
Bronze plaque: Best case time.
Silver trophy: Average time.
Gold statue: Proof of all of the above.
1000 tons of Platinum: Find an input that will loop in under 100K iterations.
Sussman's head in a jar of formaldehyde: Find an input that will loop in only 100 iteration.
A ticket to Gensokyo and a free Touhou: Find an input that will loop in only 2 iterations.

Name: Anonymous 2013-07-03 3:42

>>1
Will the touhou be my slave?

Name: Anonymous 2013-07-03 3:48

it should be nice to have a slave 2hu you can send her to work as a prostitute or a construction worker, a janitor at the very end (since she has neither papers not education to work somewhere else) and get all her salary

Name: Anonymous 2013-07-03 3:50

>>3
Alice would have maximum utility, since you could enslave her puppets.

Name: Cudder !MhMRSATORI!fR8duoqGZdD/iE5 2013-07-03 6:42

Worst case is 2^128.

I'd probably attack this problem with a SAT solver.

Name: Anonymous 2013-07-03 6:52

Oh Cudder, my Cudder!

Name: Anonymous 2013-07-05 21:27

OP, could you be more specific on how the input and output are to be typed?  For example, there's some funny business that goes on if you do the obvious echo "foo" | md5sum | md5sum | ... with converting between unsigned char and char representation.

Name: Anonymous 2013-07-06 3:18

>>169
I tried to fix some things and got banned. Just leave things as they are.

Name: Anonymous 2013-07-06 3:43

>>171
Nobody needs you bump threads, especially non-programming ones, you fucking idiot. Just kill yourself.

Name: Anonymous 2013-07-06 3:47

oh nice, now we have a rampant moderator who deletes everything, may be even with a script
king log is better than king heron, you know, see aesop's fables

>>173
calm down dude, if the thread is already at the top it doesn't matter if i use sage or not

Name: Anonymous 2013-07-06 3:56

>>173
sure moderator-san, let's leave threads from 2007 on the front page!

moderator-san is wise, and is certainly not suffering from autism, i will dispatch myself swiftly

Name: Anonymous 2013-07-06 4:09

>>173
Cool your jets, pops

Name: Anonymous 2013-07-06 4:11

Best case: 2 iterations
Worst case: 2^128 + 1 iterations
Average case: No idea, but probably close to worst case, since MD5 is designed to have a low possibility of hash collisions.

Name: Anonymous 2013-07-06 17:01

>>171
suck my anus

>>1
interesting. note that after n iterations, there are (n^2-n)/2 different possible sums.

Name: Anonymous 2013-07-06 19:10

>>178
no you suck my anus, ``faggot''

Name: Anonymous 2013-07-07 0:10

This basically boils down to finding a collision between an input and a valid hash, correct?

Name: Anonymous 2013-07-07 8:11

>>180
no, dumbshit

Name: Anonymous 2013-07-07 11:53

>>1
I found an input that will loop in just zero iterations!

Name: Anonymous 2013-07-07 11:58

>>182
define zero

Name: Anonymous 2013-07-07 12:00

>>183
your IQ

Name: Anonymous 2013-07-07 13:51

>>180
idiot

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