Afgelopen zondag stuurde Lauren Weinstein, lijstbeheerder van het Privacy Forum en mede-oprichter van de People For Internet Responsibility, onderstaand e-mailbericht rond. In het bericht zit een geheime boodschap verborgen. Kwisvraag: welke tekst is dat?

Date: Sun, 16 Sep 2001 17:20:50 -0700 (PDT)
From: Lauren Weinstein (lauren@vortex.com)
Subject: Getting a grip on encryption realities

It may be time to pause for another dose of reality. With calls from various quarters rising for various encryption bans, let's put aside most issues relating to the undesirability of such moves for a moment and just look at the matter of practicality.

Anyone who wants to encrypt their materials with strong encryption has the technical ability to do so. No laws or regulations can put that genie, particularly in terms of software-based systems, back into the bottle. Terrorists are unlikely in the extreme to heed such prohibitions in any case.

To make matters even more complex, it's possible to obscure heavily-encoded messages in seemingly innocuous ways. Only the imagination really limits the possibilities. Highly-encrypted messages can be spread out through photographs, computer images, faxes, audio files, plain text, and any number of other media. Ostensibly ordinary files, documents, or statements can contain all manner of encoded data, with the data itself encrypted via any mechanisms up to and including one-time pads.

Let's be clear about this. Degrading the strength of communications between honest citizens will not prevent disasters like Tuesday's, but will make those honest citizens less secure. Yet the calls for banning strong encryption take no heed of any of these realities. Obviously we must fight terrorism, but weak or "back-door-enabled" crypto systems carry a *very* high risk of being rendered ineffectual, resulting in highly sensitive and private--but completely legal--communications being exposed. Unfortunately, in the understandable fervor of the moment, many aspects of technical facts and common sense are being plowed under the tank treads of emotion.

Realistically, if we are to fight terrorism without destroying ourselves piece by piece, we need to above all be thinking clearly. How we handle the encryption debate may be a harbinger of whether or not we deal rationally with a broad range of other crucial issues in the aftermath of terrorism.

Any way you look at it, we stand at a crossroads, not just relating to terrorism but for ourselves as well. Notwithstanding wars and disasters of the past, the decisions we make now are among the most crucial we'll ever face. Doing the right thing speaks not only to today and tomorrow, but to history as well.

--Lauren--

Hint: de verborgen tekst heeft te maken met de Beatles.

Encryptie voor gevorderden

Bij veel encryptietechnieken spelen priemgetallen een cruciale rol. Veel sleutels zijn het product van twee grote priemgetallen. Hoe langer de priemgetallen zijn, hoe moeilijker de sleutel is te kraken, want dat vergt veel computerkracht. Om nieuwe sleutels te maken is het dus belangrijk om zoveel en zo groot mogelijke priemgetallen te verzamelen.

In de jacht op nieuwe priemgetallen worden wel eens vreemde vondsten gedaan. Met onderstaand priemgetal is iets vreemds aan de hand. Het is namelijk illegaal. Kwisvraag voor wizzards: waarom is dit priemgetal illegaal?

                                                     4
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Netkwesties zal het u graag vergeven als u het antwoord niet in één oogopslag ziet. We zullen dan ook maar direct het antwoord geven: dit priemgetal is geschreven in het tientallig stelsel. Hexadecimal (zestientallig) uitgeschreven vormt dit getal een GZIP-bestand van een programma om het DVD Movie-encryptieschema te ontcijferen. In de Verenigde Staten is distributie van een dergelijk programma verboden.

Het illegale priemgetal is gevonden door Phil Carmody. Zou Phil nog andere hobby's hebben?

[WZ, 20 september 2001]