The Watermasked Cucumbers and their watermarking blog

They crazy like fools

2011-01-12T06:01:00.004-05:00

Amazing! After more than ten years in the business, we still discover, by random walks on the Internet, conferences of our domain we didn't know. What about it Daddy Cool: International Workshop on Content Protection & Forensics.

We haven't received any CfP. Well, if their plan was to keep confidential their private party on the beach of Barcelona, no way, the cucumbers wrote it down on their agenda!

Vamos a la playa!

Miss cucumber

PS: Blogger editing sucks!

Happy New Year!

2011-01-03T09:51:00.004-05:00

So? Plenty of gifts this Xmas? Well, we received an unexpected one from our biggest fans (yes, this blog does have fans!), the organizers of the next IH conference in Prague. Thank you so much! Here is their message:

Dear Watermasked Cucumbers,

organizers of 13th Information Hiding decided to wish merry Christmas to
all cucumber folks and hope that their blog will be as fun as it was so far.
As a Christmas gift, we grew special cucumber for you. We call it
Cucumis Infohidus. Unfortunately, we have only one piece of this special
plant. Since shipping such a special gift to you may be dangerous, we decided
to make a real photograph of it (really, it is not a forgery :) ).

If you come to Prague in May 2011, we will gladly give you the real
Cucumis Infohidus.

We hope that your blog will enjoy this piece of special and
only-of-this-kind plant as we are.

Have fun,
Tomas & Tomas & other info hiders

When Dexter goes to conference

2010-12-13T10:46:00.005-05:00

Tonight is the night, welcome party. Be careful, it is hard to find a way among this jungle. Everybody welcomes you with big smiles. Some are sincere, others lie. Some are your friends, some appreciate your work, others are reviewers who nailed down your paper with unfair arguments. But one is never sure. Who is who?

"- Hey! Hello! Are you presenting a paper?"

Strange to ask me such a pretendedly innocuous question right away! Usually one starts with "when did you arrive here?"… This is suspicious. I always attend conference to present a paper luckily accepted. But this conference is the only exception, and therefore his question is very embarrassing. He knows this, he did it in purpose.

Except that I noticed your little game, I am security minded, I see worst case attacks everywhere, I am Dexter. The server cuts cheese with a big knife. And the lake is just nearby. It is time to say goodbye to my 'good friend'. There will be a no-show at this conference.

Invited speakers

2010-05-26T05:32:00.003-04:00

How to boost the appeal of a conference which had a relatively low number of submissions?

Here is the trick:

1) Maintain the acceptance ratio as low as possible,

2) Fill the program with sexy invited speaker talks.

Examples:

- Ton Kalker @ MMSP 2010, "Protected Video Distribution in the Networked Age"

- Gabor Tardos @ IH 2010, "Capacity of collusion secure fingerprinting - a tradeoff between rate and efficiency"

- Pim Tuyls @ IH 2010, "Hardware Intrinsic Security"

- Boris Skoric @ IH 2010, "Security with Noisy Data"

Miss cucumber, from the travel agency desk.

About the conferences acceptance rate

2010-04-28T17:09:00.009-04:00

In this corner of the ring, the famous IEEE International Conference on Image Processing in its 17th edition, parallel sessions, poster sessions, plenary talks, exhibition hall, so many sponsors that they can't list them, more than a thousand attendees expected, and this year so many submissions that its PC was desperately looking for reviewers from the watermarking community -- even though some of your favorite reviewers didn't get any content security paper to review: that's the sad point in striving (or not being able) to manage such a huge event.

In the opposite corner, the small and dying Information Hiding workshop, single threaded session, no fancy poster, no big head speaking, no exhibition hall, one unique sponsor (Technicolor) and so few submissions that the acceptance rate is likely to be larger than 1/2.

Let us look at previous fights (thanks Google Scholar for the statistics):

Barni (SPIE 109 cit. , ICIP 87 cit., SPIE 77 cit., SPIE 77 cit.)
Cachin (IH 425 cit.),
Cox (IH 347 cit., ICIP 117cit.),
Delp. (ACM 133 cit., SPIE 123 cit., SPIE 115 cit.)
Fridrich (SPIE 256 cit., IH 239 cit., IH. 214 cit., ICIP 160 cit., ICIP 100 cit.),
Kalker (SPIE 199 cit., ICIP 96 cit.)
Kutter (ICIP 233 cit.)
Wong (ICIP 310 cit.)

So, which one of two will you attend?

Well, that big foreseen acceptance rate for IH is not very attractive. Some researchers discard such conferences, or are not given credits for their papers published in conference with so big acceptance rate. This is why I say "dying" IH: in our sad times, ROI on advertising might be considered more important than sound research.

HOWEVER, your favorite watermasked cucumbers have been reviewing for both events... and frankly, from what they've read, the IH papers were far, far better.

We do not say that there were all great, but significantly better than ICIP submissions on average (not to say: median). Therefore, judging a conference from its acceptance rate is just as silly as when judgments go on upon only one criterion (notice the alliteration).

Conclusion: if you are solely interested in data hiding and content security, you'd better go to IH. Period.

Miss Cucumber.

Truth hurts

2010-04-16T10:35:00.007-04:00

If you want to convince people that digital Forensics can be useful, here is a collection of interesting links.

The most impressive ones are the tampering collection throughout history built by Hany Farid and the museum of Hoaxes.

A smaller and contemporary list can be found on this Spanish web site, and the top ten of doctored photos (a politically correct expression for fakes) presents event obvious fakes.

Tzatziki

SPIE get closer to the Village People

2010-04-13T04:39:00.003-04:00

For 2010, the SPIE conference on Media Watermaking, Security and Forensics leaves San-Jose to meet San-Francisco (more exactly its International Airport).
On good trafic conditions, the Airport is 30mm far for downtown by car, and the same by the subway, which means possibly interesting after-sessions.

Deadline for extended abstract and summary: 28 June 2010.
More information Here.

Stormy SPIE

2010-01-28T02:40:00.011-05:00

From Mr Tsukemono,

Mr. Tsukemono was sad to see only 4 papers related to Steganography and Steganalysis on the whole conference. The general trend of the decreasing number of papers continues, as WIFS enjoyed only one such paper. But the good news is that the quality of papers was good. And quality is preferred over quantity. 
Mr. Tsukemono has enjoyed following two papers:
  - Application of Viterbi algorithm to asymptotically reach rate distortion bound due to T. Filler, J. Judas and J. Fridrich.  
 - YASS algorithm is finally broken by blind steganalysis, though 1200 features makes Mr. Tsukemono rather bitter.
 Remark: The session was dominated by Binghamton University, from which 3 out of 4 papers came. What are the other groups doing? Are they saving papers for IHW, ACM, WIFS, IWDW, ICIP, ICASP or what else? We should hope.  By considering number of papers and sessions, forget steganography and steganalysis, forensics is the hype now. Forensics was subject of  5 sessions. We could see great papers coming from Dartmouth, Dresden, Binghamton, Purdue, and others. It was not coincidence that 3 papers dealt with the same topic, i.e. how to efficiently search and match fingerprint in large database. Each paper approached the problem from completely different direction. 
Another important point: we could finally see an attempt to plant a new camera fingerprint to the image (and method to detect this forgery).  The watermarking is getting popular as well. The number of accepted papers was so large that the papers had to be presented in parallel sessions. Good for watermarking, bad for conference attendees.  Although tutorial talks this year lacked stunning pictures from deep sea or from deep inside of the human body, they made Mr. Tsukemono a goose flesh. He realized that his new shiny iPhone is spying on him...

IH 2010 announcement

2009-12-23T13:44:00.002-05:00

IH 2010 will be located in Calgary. Here is the website:

http://ih2010.cpsc.ucalgary.ca/

Note that the submission deadline is in 3 months.

Miss cucumber, a green dress for Xmas.

IEEE WIFS'09

2009-12-16T16:08:00.007-05:00

Open drum roll. "Ladies and gentlemen, this is the first edition of IEEE Workshop on Information and Security (a.k.a. WIFS). This is the first day of the first edition. This is the first session of the first day of the first edition. This is the first..." Well, this first session will not go down in history, but, this conference was indeed very good:

- a conference theater looking like the "Who wants to be a millionaire" stage (thanks BT!),

- low acceptance ratio,

- high attendee per speaker ratio,

- a good mix of all that matters in information security (watermarking, forensics, traitor tracing, biometrics, steganography, fingerprinting, cryptography...)

- refreshing invited speakers: a judge with subliminal erotic pics (is that what is called the 'french touch'?), a megalo but introspective security expert, and a frightening virus hunter ("Stay away from computers!")

- nasty questions and hot sessions (especially the "We will rock you" traitor tracing speeches), may be too hot since it trigged the fire alarm (thanks BT!).

- the nice playlist in the control booth (thanks BT!).

Miss cucumber back from ye olde London

Biodiversity

2009-11-26T04:10:00.005-05:00

Modern times are hard times for bio-diversity, this also holds in the watermarking environment.

Here is the program of SPIE Media Forensics and Security XII.

New: invited talks, security of biometry, and (seemingly) awards.

Just like IEEE-WIFS?

- Same topics,

- Same community,

- Same bosses,

- Same period (december-january).

Miss cucumber

Cucumber spirit hits SPIE Optical Engineering

2009-10-07T08:35:00.006-04:00

By Cucumber without spiced ham

Ever feared checking your Inbox for a request to review another spam paper? Spam papers in watermarking commonly share the following features:

The author is not concerned with frivolousnesses like the difference between zero-bit and multi-bit watermarking;
While the technique is not designed to survive geometrical distortions, a 3° rotation generally "demonstrates the high robustness of the proposed approach to geometrical transforms" -- and, of course, pseudo-cropping is always meant for plain regular cropping;
For zero-bit watermarking (which is definitely the same as multi-bit), the threshold is always taken from the Barni et al. paper [1] ensuring a 1e-8 probability of false alarm. No threshold is ever allowed to include another constant than 3.97 which is engraved in the holy Eq. 15 of the said paper. Whether the computation actually applies straightforwardly to the submitted paper is of secondary interest;
Explicit distortion specification is generally omitted for the sake of simplicity (oh! and Lena looks good anyway when printed on a 2 inch square!);
Security is ensured by the use of a secret key;
Spell-checking is left to the reviewer;
The results always clearly and unconditionally demonstrate the superiority of the proposed method in any area of comparison.

It appears however that the times they are a-changin' [2]. A Cucumber of ours recently received the new instructions for reviewers from SPIE Optical Engineering, as part of an invitation to review another spam paper. Hell! These new instructions read:

"Although this paper need not be exceptional, it should add
significantly to the field for you to recommend acceptance or revision.
Lately, a substantial number of papers have been submitted that can be
called "not wrong" papers. These are papers that contain no errors, but
they also lack any new and useful information that would move your field
forward; they may provide no citable results, or document so little
progress that researchers in your field will ignore them. These papers
take up your time and ours; they clutter up the literature; and they do
not advance research in the field. If you find this paper fits this
description, you should recommend that the paper be rejected."

That's pretty good news it finally got written in plain English.

References

[1] M. Barni, F. Bartolini and A. Piva, Improved wavelet-based watermarking through pixel-wise masking, IEEE Trans. Image Proc., vol. 10, issue 5, pp. 783--791, May 2001.
[2] R.A. Zimmerman, The times they are a-changin', Columbia Trans. on Bob Dylan, Special Issue on The Times They Are A-Changin', January 1964.

ACM mmsec 09, the hidden (and fun) parts

2009-09-15T02:07:00.014-04:00

By Tsatsiki
Miss cucumber is right, there were interesting papers in the ACM workshop on Multimedia and Security. And the participants had some fun as well. This is mainly thanks to one guy: Scoot Craver, the co-chair of the conference.

Scott is born data-hider, let me tell you why.
Firstly, when the participants arrived to register, they were offered a nice usb key like this one:

- these were the two first hidden messages. (look at it upside down)

Secondly, Scoot launched the workshop saying that there was a hidden (and cyphered) message on the building of the conference (the Friend Center in Princeton). This was true indeed since during the next coffee break the participants were able to see this:

- this was the second hidden message! Did Scoot add the bricks just for the conference? François Cayre, knowing ASCII code by heart, succeeded to decipher the message, while some others asked Google for the solutions.

Of course the talks of the workshop were also filled with hidden information (it was voluntary or not) and two of them were rather fun:
- the magic display cable (Atakli et al.) which is able to recognize, descramble and display encrypted images of a computer desktop on the fly,
- during the rump session, a teaser of the first contest on steganography was presented by T. Pevny. According to him it will be launch in 2010 and called BOSS (for Break Our Steganographic Scheme). I think that this contest is going to be rather popular.

Let's hope that WIFS 2009, the next conference on data-hiding, will be as fun as this one.

ACM mmsec 2009: the rise of the dragon?

2009-09-14T07:27:00.007-04:00

ACM mmsec took place under the black and orange flags of the amazing campus of Princeton University, 7-8 september.

The general chair was Ed Felten, Prof. of Computer Science and Public Affairs (might be the only one to have this title), and the director of the brand new Center for Information Technology Policy.

He made a very good introduction speech calling for more discussions between computer scientists and law makers, and then, he almost disappeared from the conference (I could understand, after all, Monday was Labor day)! Never mind, Scott Craver organized a very good social event between nowhere and goodbye in a house near the lake and the lunch in Prospect House was also terrific.

Helas, there were only 40 to 50 attendees! Scott Craver defended the idea that, despite the decline of submissions, their overall quality was good. Therefore, good papers don't fear the financial crisis (if this is the real reason for the submission number decrease).

Like in IH'09, there were indeed quite few papers of lower interest so that the idea of S. Craver holds.

So, what is hot? MP3 quality assessment! The scenario is as follows: a low bitrate MP3 file is transcoded at a higher bitrate and sold as a pretendedly high quality tune. How to detect this? By revealing the signs of a double compression. Actually, H. Farid also presented a talk about double compression to detect video edition. Three speeches, three different approaches: from the "I don't know what happens, but my SVM will tell" heuristic to a more convincing statistical modeling.

The asian dragon? The era of old asian professors reading with difficulty their slides full of approximative english long sentences is over. We are witnessing, in multimedia security (it is probably the case for a long time in other fields), a new generation of young, convincing communicator and quite good researchers. Among the speakers but also in the audience. Some aggressive but very relevant questions were asked.

We also met the future leaders in steganalysis: Jan Kodovsky and Jan Judas replacing the two Tomas evil twins leaving Binghamton (Tomas has already left for Grenoble and soon Praha, while Tomas is finishing his ph.D). The Czech eagle vs. the asian dragon... An interesting battle is coming.

Talks I liked:

- "Two Key Estimation for the Borken Arrows watermarking Scheme", P. Bas and A. Westfeld. Another evil twin couple is born. How to break Broken Arrows (the watermarking technique used for BOWS-2) again and again. I guess, since P. Bas is one of the inventor, it is easier to analyze one's own scheme.

- "Additive Spread-spectrum watermarking detection in demosaicked images", P. Meerwald and A. Uhl. Hack your camera! The Austrian team modified the firmware of a camera so that watermark embedding is done in the device just after the CFA capture. Cool hack! This rises the challenge of watermark detection after demosaicking.

- "Exposing digital forgeries in video by detecting double quantization", W. Wang and H. Farid.

The best paper of all the "double compression" works in this conference. Nice but oversimple talk (as always), which plays the role of a teaser to read the paper for further information. The paper is indeed good: statistical model, identification of the parameters with an 'E-M' like algorithm, hypothesis test.

- "Calibration revisited" J. Kodovsky and J. Fridrich. My understanding about calibration is that natural images follow no statistical model or a so flat pdf p(X) that no hypothesis test will work with so few discrimination. Calibration is about estimating a set of parameters P specializing the model, switching from the flat marginal p(X) to the much more contrasted conditional p(X|P). Calibration is about statistical modeling. Whereas this paper uses calibration with SVM, which is, IMHO, the contrary of statistical modeling. SVM means "I don't know how to model things but, once trained, the SVM will find its way". Therefore, I was a little confused by this approach. But the results are there.

- "Square Root Law" A. Ker. During IH'09, I was not convinced by the talks about the square root law: It is was not enough formalized, the assumptions were not clearly delimited, so that if the law indeed holds, we could not tell the real reasons. This is exactly what Andrew Ker did in between the two conferences, and now, this became serious math with theorem (conditions and results) and proofs.

- "Detection of seam carving and localization of seam insertions an digital images" A. Sarkar, L. Natarj, and B. Manjunath. Seam carving is this image processing tool. It a priori seems a 'mission impossible' to detect seam carving, but a heavy tool (a 324 Markov features classifier) starts producing good results. Work in progress. A maybe too dense presentation.

Miss Cucumber

IEEE DSP 2009

2009-07-08T16:19:00.005-04:00

What would you expect from a conference located in a gorgeous place (Santorini, Greece), during summer and with an acceptance rate of 76%?

It was very good (Sea, Sirtaki & Sun), and very bad (security with no secret key, security with no threat analysis,...). So bad? No, so nice invited talk by M. Unser, nice compressed sensing presentations (link with traitor tracing becomes more and more obvious). And what about watermarking? Although there were 5 sessions dealing with multimedia security and forensics, I was quite disappointed in general. Some good presentations:

Content-Adaptive Semi-Fragile Image Authentication Based on JPEG2000 Compression, M. Schlauweg. The idea of J. Eggers but pushed to a more practical level.
Blind DT-CWT Domain Additive Spread-Spectrum Watermark Detection, P. Meerwald. The idea of Loo & Kingsbury, but improved to a more practical level. At last, someone no longer uses PSNR for quality assessment.
Analysis of Denoising Filters for Photo Response Non Uniformity Noise Extraction in Source Camera Identification, I. Amerini. At last, somebody noticed that since PRNU is multiplicative noise, then, linear estimation is not the optimal. Too bad, the correlation is still here.

Miss Cucumber from the tatziki country.

Something's rotten in the realm of watermarking?

2009-06-25T15:23:00.014-04:00

2009 is a bad year for watermarking conferences. All of them (IH, MMSEC, IWDW, SPIE, ...) are facing a low submission number. There are certainly too many yearly conferences, but no PC wants to kill its child. Too bad! Clearly, publishing papers is no longer a problem.

Some think this is due to the brand new "yet another conference on content security", ie. WIFS. THE conference which would wipe out all the others. But no! There were 120 submissions. Not enough for the organizers who decided to restrain their ambition, as I have been told. WIFS might be single threaded without any poster session (enter the rumormill!). Maybe, they were expecting too much for a first edition.

Some think this is due to the financial crisis. Researchers have no money for traveling. The Earth thanks them for the saved CO2. But no! Conferences of our cousins the crypto broke submission records in 2009.

So? what is rotten in the realm of watermarking? Time to move on to another realm? Which one?

But there is a glimpse of hope at the end of the 2009 black tunnel. According to the latest Journal Citation Report, the TIFS journal's impact factor has jumped from 1.089 to 2.23. It is currently in the first third of the JCR ranking for electrical engineering journals, which is really good.

Conclusion: Stop calling your travel agency, and write long deep and damn good journal articles!

Miss Cucumber switching the gossip radio off.

Who judges? Who does science?

2009-06-16T18:11:00.004-04:00

No need for links here. One day or another, we all stumbled upon one of these papers in which the hidden payload is a binary bitmap logo. Maybe it is deeply rooted in one of the founding papers of the field.

Anyway. The point is: Are we doing science or not?

If we are really doing some science, we are preferably to talk about quantities like capacity. In real life with sound experiments, it boils down to compute/simulate the Bit Error Rate (BER).

But then people come around and say that a judge will better recognize a logo than the fact that a probability is quite low. We agree. A judge does not do science.

But it is always easier to make a covert channel with a given BER carry a given logo, than to compare two given data-hiding schemes only based on the visual appearance of the recovered logos.

We all aim at doing science. So please: No more logos. Please.

On image steganography (as people do it)

2009-06-16T17:41:00.006-04:00

For sure, steganography is becoming more and more interesting.

But hey! What about all those papers dealing with bitmap images?

Do any of you Estimated Readers ever share any images in BMP or PGM format? Do you all trust these awesome steganographic rates?

Images in GIF format are encumbered with patents and JPEG2000, apart from Digital Cinema, is mostly unused on the WWW. Old school JPEG still rules.

Guess what? Due to the DCT energy compaction properties, it is pretty sure that the actual steganographic rates are to be found much lower than what claimed for bitmap images.

And it is because of the popularity of JPEG, not because of distortion reasons.

The real issue is not how many bits are to be hidden into lena.pgm, rather in lena.jpg. Even better: how many bits can be hidden into a bunch of contents?

Distortion-free 3D steganography!

2009-06-16T13:28:00.006-04:00

Most of us think as data-hiding as a communication problem with side-information at the encoder. This widely accepted view has led to dramatic improvements of data-hiding techniques over the years. As a direct consequence, any watermark can be seen as a noise that is added to the host content.

These days, a new trend is emerging in 3D data-hiding. Such data is twofold: there is geometry and there is connectivity. Roughly speaking, geometry is a bunch of 3D Cartesian samples, and connectivity is the way the vertices connect to one another. Some people, including several of the most respected in the mesh processing area (see this paper by Bogomjakov, Gotsman and Isenburg) [1], want to hide information in the way the connectivity is described: since geometry is not affected, it leads to distortion-free data-hiding!

To us, it reads like "communications at no power" and other "infinite capacity channel" odd stories. Frightening. Sounds like a definitive breakthrough in information theory.

But wait!

There is a problem. The real question is whether connectivity should be considered useful to describe 3D data. The answer is not easy. There is already a host of works dealing with 3D point clouds data and how to synthesize connectivity from scratch. But there is more: Isenburg has done extremely interesting works on some sort of a "ghost geometry" that is already present only in the connectivity information (see his connectivity shapes).

Turn again to data-hiding as we know it: with regularly sampled host contents. Those ones that we love and that do not need description, except the dimensions of the image or the duration of the song.

Now let's make the following crazy assumption: each and every pixel of an image is to be numbered and transmitted separately. The decoder now has to know the neighborhood of every pixel. Yes. And we do not transmit triangles anymore (like for 3D meshes), but quads. That's images with explicit connectivity.

And finally we can do the same thing: distortion-free data-hiding for images. Sounds weird uh?

Interestingly enough, the paper by Bogomjakov et al. states that one needs to have a reference ordering of the vertices, so the decoder can catch the difference with the transmitted connectivity and compute the hidden message. Similar ideas are shared with so-called permutation watermarking. Therefore, there is actually some sort of distortion in their scheme. BTW, their scheme also has a capacity!

Why people transmitting images do not send quads with YUV/RGB values being the attribute data? That's because everyone assumes this reference ordering of the pixels inside an image. Everyone is happy with YUV/RGB values only.

And since there is this implicit public reference ordering of the vertices and the decoder can catch the difference, an adversary should be able to detect the hidden information quite easily. Then why is it called steganography?

So let's make it clear once for all: these guys do data-hiding on graphs. They don't do distortion-free 3D steganography. For sure.

[1] Although Gotsman already did some sort of Karhunen-Loeve Transform based compression for 3D meshes... Either it's not as real-time as claimed (one needs the decoder to compute the basis vectors -- cost: several O(N^3) diagonalizations of ~500x500 Laplacian matrices), or it is not compression (one needs to transmit the basis vectors). The improvement presented here suffers from a problem apparented to the Gibbs phenomenon.

Information Hiding 2009

2009-06-16T09:04:00.007-04:00

Information Hiding is one of the oldest workshops on Data Hiding. The 11th edition took place in Darmstadt, June 8-10. The organizers were Stefan Katzenbeisser (TU Darmstadt) and Ahmad Sadeghi (Univ. Bochum).

One third of the papers dealt with Steganography, one third with forensics (active or passive), the others with traitor tracing and exotic applications. This edition faced a low number of submissions, hence, some accepted papers were not so good.

The German community was very impressive and well organized. Several towns/universities clearly carry the label "IT Security" and/or "Multimedia Security" and get huge fundings: Bochum, Darmstadt, Dresden and Magdeburg.

Steganography becomes (at last) a noble science. Papers are more and more theoretical (see Tomas Filler, Andrew Ker or Rainer Bohme very interesting talks). On the contrary, forensics are always very ad-hoc.

The most controversial talk was "Hardware-based public-key cryptography with public physical unclonable functions" by M. Potkonjak. From what I understood: Take a chip implementing a network of XOR gates. The system has w binary inputs, and w outputs. When the input changes from NULL to w-bit message M, many glitches appear at the output before it is stable. Indeed, these astable states of the output depend on the delay of each gate. Therefore, at a given time t (before stability), from one chip to another, the output is very random.

This could be used to identify the chip. But, here, the authors propose to use this for asymmetric cryptography. Basically, Alice publishes the model of her chip (ie. the set of delays). Bob simulates the scenario above thanks to this model. He sends the output C to Alice. Alice has the hardware, she can make a brute force attack to find back M. Eve must software simulate like Bob. Eve must lead a brute force attack like Alice. However, software simulation is much much slower, and a brute force attack is not tractable if the number of gates is big enough. This was quite a controversial talk: "Public key cryptography relies on non-proven conjectures, whereas here, we resort to technological and physical laws preventing the manufacturing of fully identical systems." What a bold statement! No need to say that the cryptos in the room were coughing.

Miss cucumber, back from Darmstadt