Archive for the ‘Science’ Category

Licht & Schatten

September 19th, 2022 No comments

“Licht wirft keinen Schatten. Es ist das Objekt, das den Schatten wirft.”

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The Internet never forgets

October 18th, 2019 No comments

1. Can we permanently delete our data from the Internet?

The short answer is “no”. Computer system don’t know an action that deletes data. When data is stored on a storage device and want’s to be removed, the computer just removes the file pointer. The original data still is left at the very same, original place. The next time data is saved on the same storage device, the computer eventually overwrites the old data. Once this is repeated many times, it becomes more and more difficult to reconstruct the original data, but in many cases this still can be done. Think of it like a footprint in the sand. The footprint is not deleted, but once you step many times over the same footprint, the original one can hardly be seen, but is still there.
The Internet is a very large network of computers, servers, nodes, gateways, routers, clusters, etc., which means that every time you copy data to the Internet it travels a long way from your device to the remote location, where your data is written to a storage device. When traveling all the way through the network, your data is copied, cached and backed on each node or gateway. The very same data is copied so many times that it becomes impossible to control on how many places the same data has been written to a storage device. Even at the remote endpoint a computer cluster is copying the data again for reliability and redundancy reasons.

Once you try to delete and remove such data from the Internet, you might not see it at the original location any longer, but the data will still be there in all copied places for a long time, until it is overwritten many many times.

Private, confidential data does not belong into the Internet. The Internet was not invented for that purpose. The origin of the Internet, the former arpa-net, was to publish and distribute data and information on scientific research, academic knowledge, information and content from libraries and book collections.

The Internet never forgets.

2. Can we recover Deleted or Lost Files?

Yes. Depending the resources, the disposability and the mechanisms one can more or less easily recover lost data. Again: all the data that travels through the Internet is copied and cached all over many places. For example there is a robot called “the Internet archiver”, which is a search spider that follows all the links it can find in the Internet and crawls through the network. Once it finds data it copies and stores it, where one can recover it again. Further there are large data crawlers that are gathering large amount of data for data mining purpose, copy and keep the data in historical archives. Once somebody has access to such resources, one can easily recover “lost” data.

Computer systems don’t know the concept of “loosing” data. Think of Cloud computing like fog. In nebulous computing data can slowly fade away, but is not completely removed, just overwritten. It’s like your memory in the brain works: if you don’t repeat the information from time to time again, you start to forget. Try to delete a memory from your brain. The more you try to delete it from your brain, the more you will keep it, because you repeat and continue to remember.

Content delivery networks work that way: the more the same data is requested, the more it is copied to the very surface of the network supply.

The question is: are you clever enough to ask the right question to retrieve your lost data?

Categories: Science, Technology Tags:

Kerckhoffs’s principle

November 2nd, 2015 No comments

“The security of a cryptosystem should depend solely on the secrecy of the key and the private randomizer, not of the secrecy of the used cryptographic algorithm.”


“Un grand nombre de combinaisons ingénieuses peuvent répondre au but qu’on veut atteindre dans le premier cas ; dans le second, il faut un système remplissant certaines conditions exceptionnelles, conditions que je résumerai sous les six chefs suivants:

1° Le système doit être matériellement, sinon mathématiquement, indéchiffrable

2° Il faut qu’il n’exige pas le secret, et qu’il puisse sans inconvénient tomber entre les mains de l’ennemi

3° La clef doit pouvoir en être communiquée et retenue sans le secours de notes écrites, et être changée ou modifiée au gré des correspondants

4° Il faut qu’il soit applicable à la correspondance télégraphique

5° Il faut qu’il soit portatif, et que son maniement ou son fonctionnement n’exige pas le concours de plusieurs personnes

6° Enfin, il est nécessaire, vu les circonstances qui en commandent l’application, que le système soit d’un usage facile, ne demandant ni tension d’esprit, ni la connaissance d’une longue série de règles à observer.

Tout le monde est d’accord pour admettre la raison d’être des trois derniers desiderata ; on ne l’est plus, lorsqu’il s’agit des trois premiers.”

ex “La cryptographie militaire” Auguste Kerckhoffs, janvier 1883

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The most powerful tool

October 13th, 2015 No comments

“The most powerful tool is your mind!”

Categories: Art, Science Tags:

78 Hydroptère

August 26th, 2014 No comments

The 78 Hydroptère is currently cruising around in the lake of Zurich. – What a beauty!

Image 2014 CC-BY-NC-SA copyleft Tristan Hauser

23 years of Linux

August 25th, 2014 No comments

Congratulations, Linus Torvalds, and thanks for inventing and writing the GNU/Linux Kernel since 23(!) years!

Hello everybody out there using minix –

I’m doing a (free) operating system (just a hobby, won’t be big and
professional like gnu) for 386(486) AT clones. This has been brewing
since april, and is starting to get ready. I’d like any feedback on
things people like/dislike in minix, as my OS resembles it somewhat
(same physical layout of the file-system (due to practical reasons)
among other things).

I’ve currently ported bash(1.08) and gcc(1.40), and things seem to work.
This implies that I’ll get something practical within a few months, and
I’d like to know what features most people would want. Any suggestions
are welcome, but I won’t promise I’ll implement them 🙂

Linus (torv…

PS. Yes – it’s free of any minix code, and it has a multi-threaded fs.
It is NOT protable (uses 386 task switching etc), and it probably never
will support anything other than AT-harddisks, as that’s all I have :-(.

Source: usenet comp.os.minix


January 20th, 2014 No comments

Hello World!


Hacker schedule 2014

January 6th, 2014 No comments

7. – 9. March 2014 eth-0
17. – 21. March 2014 Troopers
18. – 21. April 2014 Easterhegg
29. – 30 May 2014 HITBSecConf
13. – 15. June 2014 Chaos Singularity in Bienne
19. – 22. June 2014 Gulasch Programmier Nacht
July 2014 SIGINT
August 2014 ICMP7
September 2014 Datenspuren
24. – 26. October 2014 Hackover
27. – 30. December 2014 31C3


July 18th, 2013 No comments

Aus der Reihe “dem Philosoph ist nichts zu doof”:

„Beim Erwachen hatte ich schon so viele Einfälle, dass der Tag nicht ausreichte, um sie niederzuschreiben.“

Zitat Gottfried Wilhelm Leibniz

… drum bleib’ ich heute im Bett um gar nicht erst der Welt Schaden anzurichten.

Categories: Culture, Science Tags:

The astrophysical perversion of copyright infringement

February 17th, 2013 No comments

The german GEMA, – which ought to represent “intellectual property” as an institution, – today blocked several youtube clips of the meteorite shower that arised over Russia yesterday, within Germany. – Apparenty GEMA tries to enforce God’s creation on a copyright & “intellectual property” level! – Please, – therefore, – find the according youtube clips for free (as in free beer) download hereby:

direct download: ogv webm mp4

direct download: ogv webm mp4

direct download: ogv webm mp4

direct download: ogv webm mp4

direct download: ogv webm mp4

direct download: ogv webm mp4

direct download: ogv webm mp4

… let’s hope the next meteor hits the GEMA head quartier!

Read moar

Categories: Culture, Human Rights, Science Tags: