Guus Bosman

The Full Frame Documentary Film Festival started on Thursday. I took a day off yesterday and we have seen several great films already. What a great event to have in our home town!

To Die In Oregon

The most memorable movie so far was 'To Die In Oregon', about the 'Death with Dignity' act in Oregon and Washington state, which legalizes physician-assisted dying with certain restrictions. The film describes why patients took this decision. It was a very difficult movie to watch, especially the story of a 57 year old cancer patient and her family in her last year.

Windfall

The next two films were of a much lighter tone. Windfall describes downside of wind energy, and the potential effects it has on the quality of life of people around wind turbines. It describes what happens in Meredith, a village in upstate New York, when developers visit the town to set up wind turbines. As the filmmaker said at the festival, the real power of the documentary was not so much describing the facts around wind power, but showing the people of the town. Some real characters!

Guilty Pleasures

The official opening film of the festival was 'Guilty Pleasures', a fun documentary about the Harlequin romantic books, and the people involved in producing them. Very entertaining, very nicely done. Full Frame is not only great because of its movie selection, but also because of the guests that are invited. One of the main characters of the movie was in the theater and the Q&A session afterwards was fun.

Over the years I've become an avid reader of the New York Times. I don't always agree with their commentary, but their reporting and analysis are excellent and I've come to read it several times a day.

I always wondered why they made all their news available for free. After all, other major newspapers such as The Economist and the Financial Times have had paywalls for years. We had a subscription to the New York Times in the past but a newspaper made out of paper is very inefficient -- reading it on the phone is so much more practical.

I ran into the "soft limit" of the Times within 4 days of the new month, both on my browser and my BlackBerry. It's a valuable news source to us, so as of this morning we're subscribed.

It's strange to see how easy it is to circumvent the paywall (using NoScript in your browser in sufficient); I suppose they assume most casual readers won't go to that length. Still, sending the whole article but overlapping it with a CSS popup is trivially easy to get around.

Today I read 'Uncovering Spoken Phrases in Encrypted Voice over IP Conversations', a very interesting article from the December 2010 issue of ACM Transaction on Information and System Security. (Read the full PDF version here).

The paper details a gap in the security of VBR compressed encrypted VoIP streams. The authors had earlier found that it is possible to determine the language that is spoken on such a VoIP call, based on packet lengths. Now they have expanded their research and show that it's possible to detect entire spoken phrases during a VoIP call. On average, their method achieved recall of 50% and precision of 51% for a wide variety of phrases spoken by a diverse collection of speakers (some phrases are easier to detect than others; the recall various from 0% to 98%, depending on length of the phrase and the speaker).

In other words: they can detect fairly well if a certain phrase is being used in a conversation, even though the VoIP conversation is encrypted!

Fundamentally, this is possible because VoIP packets are compressed using variable bit-rate compression and not typically "padded". Longer phonemes (such as vowels) correspond with longer packets, shorter phonemes (such as fricatives like 's', 'sh' or 'th') use shorter packets -- using sophisticated statistical analysis they can detect whole phrases.

A solution would be to add padding to VoIP packets, but that increases the bandwidth that is needed. Not only does padding increase the bandwidth because of padding itself, but it also negates a big benefit of VBR compression when dealing with quiet periods in a conversation, when one party is listening to another.

A fun read, quite accessible.

I've started a training course at work. It's called Bullet Proof Manager, and there's a session once a month. Today was the first one, and the topics were 'negotiating' and 'listening'. It was quite interesting, and I especially liked the role-play, a good exercise.

The training was in SciWorks, a technology museum for children, in Winston-Salem. There was a divers group of participants, from many different industries.