Monthly Archives: January 1970


You can contact me by e-mail via sijmen(a), by phone and Signal (most secure option) via +31652627625, or via the contact form below:

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Almost all my professional work is highly confidential and thus I cannot publicize about it. Sometimes I find time in my busy work schedule to write about some of my research which doesn’t fall under a non disclosure agreement: 2018-03-13 Security assessment of … Continue reading

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About me

For 20 years I’m an aficionado for anything related to internet security and developing secure software. I’m specialized in hacking, IT security research and performing advanced penetration testing. My specialty is breaking IT security and then explaining this in a … Continue reading

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In the media

Sometimes the media talks or interviews me about my work, and sometimes I’m asked to comment on hacking and cyber security related news: Date Website Subject 2018-12-08 ‘Nieuwe hacktruc met 06-nummers: honderden slachtoffers door sim-swapping’ 2018-11-08 Keynote presentation: … Continue reading

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My company: Secundity My resume: LinkedIn My short updates: Twitter My presentations: SlideShare

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Quite often journalists ask me to send photo’s. To speed things up I’ve collected some so I can easily reference them to this page: International news agency AFP has put up a stock video on GettyImages about my election hacking … Continue reading

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