Ok, when Micha saw my tiny hack he changed his implementation (as promised) and told me I’m not able to hack it again… Micha, your captcha failed again :P
Lets have another look to his code:
First of all he renamed the fields, so of course my last attack will fail :P
The next problem is, that the hash for a 7 isn’t the hash for another 7 of a different calculation. Maybe he’s using the arithmetic problem or the time or other things for his hash calculation. So if we don’t know how his calculation for the hash is, the last attack is senseless… Btw he told me that he’s using encryption. If you’re bored, try to break it, it’s to much for me.
But Micha bets three beer that I’m not able. So no chance to quit!
In my last post I had another idea to crack the captcha: Parse the formula.
Ok, I wrote about parsing the URI to the external server that produces the picture, of course it’s much easier to parse the title - or alt -tag of the image! These fields are human readable to get the site handicapped accessible. Of course worthy that he provides this fields!
So, after some reloads I had a small idea with what kind of problems I have to deal with:
something like: , just calculate the solution
like , first convert the formula before calculating the solution
for example , first rewrite the sum-symbol, than calculate the solution
That’s the theory, the code is this time a little bit longer:
As you can see, it’s a little bit tricky and just works for some mathematical formulas that are of interest. If he combines the converting problem with brackets or something like that, this code fails.. But the algorithm is easy to modify for such changes ;)
But respect, to crack my captcha you don’t need that intelligence, it’s feasible in much less code.
I hope he doesn’t rewrite his plugin again, don’t want to calculate that stuff by brain…
Micha was annoyed of his previous Captcha-Plugin, neither valid nor beautiful, so he decided to write his own tool for killing bots.
When I saw his new captchas I was wondering wheter he will get further comments. His captchas ask for solution of mathematical problems like or or ..
Who the hell wants to calculate that stuff!? Me not! ;)
So I developed a little userscript that solves this problem. When you take a look to the source code of his website you’ll find something like this:
So you see, there is an image created by an external server, an input field where you can put the solution and an input field of the type hidden with a crypt value (seems like a hash^^). The most of you will see several ways to hack this:
Parse the string of the image like the external server does to create the -image. So you’ll get an arithmetic problem, easy to solve.
Find out what kind of hash is in the value of the secret hidden input-field and try to find a number that matches that hash, maybe via brute force.
Solve one captcha and fake the rest ;)
Of course the last solution is the easiest one. So I solved on captcha, solution was 7 and the secret key was 9ee4251f80923e6239ae66ab50a357daa6039f04 , hack done!
The development of the userscript was more than simple:
I think that this script won’t work for a long time, so there is no download available ;)
If you want to use it, copy&paste, you know.
Ähm, before anybody starts to blame me, a similar workaround kills also my captcha-solution… :P
Yeah, completely in twitter-fever! Just developed a tweet-button.
You can see the button at the end of every post. The button itself of course isn’t my work, I just copied it from twitter, but when you click the link around it you can tweet the actual post directly to twitter! Feel free to try it! ;)
It’s more than easy. All the code you need is (replace […]):
So the code that I wrote in my theme is:
After that just using the $tweet variable at any position I like ;)
The last two weeks I took a time out. The first week I visited my sister living on Usedom, Rumpel came with me.
Those of you who are following me on Twitter may have noticed the one or other story, it was one of the best trips I made! Very funny and of course much too short ;)
We cycled a lot of km’s, climbed on trees, swum in the Baltic Sea, took sunbathes on the beach, went to Poland and so on. Detailed reports would blow up the framework of this website, but I’ll provide some pictures at Picasa, here is also a YouTube video from Poland.
And I’ve prepared a funny animated gif of an interesting evening ;)
So, if you ever have the chance to go to Usedom: Do it!!
Just read the so called Algorithmencatalog (maybe Algorithms Catalog in English!?), published by our German Bundesnetzagentur. They seem to know exact expiration dates for hash functions ;)
In this PDF file I found the following table (see original screen-shot):
* i.e. for creation of qualified certs, not for creation or verification of other qualified signed data.
** i.e. for creation of qualified certs with at least 20 bit entropy in its serial number, not for creation or verification of other qualified signed data.
*** exclusively for verification of qualified certs
Creation of qualified certs*:
suitable til end of 2009
Creation of qualified certs**:
suitable til end of 2010
suitable til end of 2010
suitable til end of 2015
suitable til end of 2016
So I hope there is anybody out there that has started to crack SHA-1 to get finished this year :P
Yesterday, while waiting in a traffic jam, I implemented a small game. I read about this game in a book and to not get too annoyed about the waiting time I opened the lid of my laptop and wrote this game. This morning I completed it with some usual stuff to increase the usability..
It’s written in C++ and you can play against the CPU. There is a strategy that makes you win in almost every case! This game is a classic in game theory, but if I provide you with it’s original name it’ll too easy for you to solve the problem with help from Wikipedia or something like that.
So just try it on you own ;)
The aim of the game is to clear all the stacks that are filled with o ‘s. The stacks may look like this:
Now it is your turn to choose one of these stacks and remove some or all o’s of it. Notice that you have to remove at least one of them and you can only remove o’s from one single stack!
After your turn, the artificial intelligence will do the same. Afterwards it’s again your turn, until all stacks are cleared. Winner is the one who cleared the last stack, so try to get the last o ;)
Here is the download.
You can choose the number of stacks and the maximum number of o’s a stack can carry:
If anybody knows the strategy, feel free to tell me!
Actually I revived my Creative Zen and had some trouble with that crazy media stuff..
Ok, every body who knows me knows that I hate that media fuss, to many functions that nobody needs, and to many failures on important stuff. How to mount an MTP-fs I explained in a previous posting, here it is in a nutshell:
With mtpfs version 0.9 and libmtp8 from sid I just experienced segfaults reported by dmesg, but the versions from squeeze just work fine.
Of course it is interesting that I’m not able to overwrite existing files:
Curious, but the workaround should be clear ;)
Last but not least I can show you how to play a YouTube video on this device. The easiest way is to install the Firefox extension downloadhelper, so you can download the song as a .flv file. The usual player don’t know what to do with .flv , and of course mine doesn’t, so convert it with mencoder. Here is an example:
The audio file doesn’t have meta data yet, so my Zen can’t find a name for it (don’t know why they didn’t implement a fallback to name it by it’s filename). To edit the meta tags you can use common tools like amarok or XMMS, I used easytag.
So you see, with a little work everything will be fine!
Just found it on F.A.T., a Firefox plugin called google-alarm! Look at this tool and recognize how much information you expose by simple surfing.
To make it work on my Iceweasel 3.5.11 I had to change the em:minVersion in the install.rdf of the .xpi archive. It’s just for noticing, I don’t provide this changed version because you should not download such things from sites like mine ;)
You should also take a look at F.A.T., they often have smart projects!