Guus Bosman

software engineering director

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dailylife

Photo exhibition

Sat, 03/26/2011 - 12:54pm

Yesterday evening we went to the opening reception of a photo exhibition in Cary, NC. The exhibition was with works by Saskia Leary and Laura Holley.

Saskia, who was born in the Netherlands, started photographing after her retirement. This exhibition was about spring flowers and the Keukenhof in the Netherlands. Saskia has been to Sofia, Bulgaria and took several nice photo's there also -- yesterday we saw one of them in a restaurant nearby.

We met up with Petra at the exhibition --it was nice to see her-- and when we went for dinner in the evening we saw several other people we know. A small world.

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internet

Uncovering Spoken Phrases in Encrypted Voice over IP Conversations

Thu, 03/24/2011 - 10:02pm

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.

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Français

Vivez la Francophonie

Sun, 03/20/2011 - 9:49pm

Today, March 20th, is the international day of the Francophonie. I didn't know this either but my teacher told me this in the afternoon.

"It's an opportunity, for French-speaking people of the entire world, to affirm their solidarity and to live together, with their differences and their diversity."

This afternoon I tried an on-line class for the first time, and it worked well. I really like my Tuesday classes, but want to practice more than once a week. I've looked for a teacher in Durham or near my work, but that turned out to be hard. So I went on-line and today I had a 1 hour lesson through Skype from a teacher in Lyon, France.

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Work NC

Negotiation training

Thu, 03/17/2011 - 9:15pm

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.

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Français

Back to work

Tue, 03/15/2011 - 9:11pm

Today was my first day back in the office. I drank the French Roast coffee, but it's not the same as a freshly brewed espresso in a Parisian café.

In the evening I went to Chicle to my French class where we practiced more on the subjonctif. It's not difficult, but you really have to get in the habit of using it.

The time difference, even though it's only 5 hours now, made it hard to stay awake. I'm going to bed soon.

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dailylife

In Paris

Fri, 03/11/2011 - 8:26am

We're in Paris, and life is good.

Highlights so far: a day in Versailles, the palace created by Louis XIV, and our first ever visit to the Louvre Museum. And the food, of course!

Sasha was at her conference yesterday and today; she'll be back in a while and we'll hit the town again. I took two French lessons, which was great.

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dailylife

A cup of camomile tea

Sat, 03/05/2011 - 10:10pm

Today we prepared for our trip to Paris, and in the process organized our storage room. In a box with things from our stay in New Jersey I found some Mighty Leaf tea, so we're having a nice cup of chamomile.

There are always a lot of small things to prepare (don't forget to return that library book, pick up the dry cleaning, last minute shopping) and I really like it that we're not getting up at a crazy early time to get to the airport. Our flight is at 8.05 pm tomorrow, from Charlotte.

During the last few days I studied about ordering meals in restaurant, and reading menu's in French (la carte, not le menu). I'm all set to order some cuisses de grenouille.

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travelling

Vacation

Fri, 03/04/2011 - 8:18pm

Tonight is the start of our vacation! Sasha is presenting one of her papers at an economics conference in Paris next week, and we're making a nice holiday out of it. Sunday evening we'll leave from Charlotte, NC to Paris and we'll stay for about a week in the City of Light.

We're really looking forward to it. We've been in Paris once, in 2004, when Sasha was already in the States and I took a high-speed train from Amsterdam when she came back from Cameroon.

About seven months ago I started studying French, and this will be a fun opportunity to practice my new skills.

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