masswerkDec 2022Strongly recommends
Epic talk (in German, David Kriesel, "Traue keinem Scan, den du nicht selbst gefälscht hast"): ▶ this video
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David Kriesel: Traue keinem Scan, den du nicht selbst gefälscht hast
David Kriesel: Traue keinem Scan, den du nicht selbst gefälscht hast on HackerTube: recommended by 4 Hacker News commenters across 5 separate months, 2019–2025.
media.ccc.de
Open on YouTubetalk · evergreen
David Kriesel's 31C3 talk, in German, on the discovery that Xerox scanner-copiers silently replace digits and letters in scanned documents. He explains how the bug stayed unnoticed in the wild for years.
Why Hacker News recommends it
Called a classic CCC talk, and the Xerox bug is cited as a cautionary tale about trusting scans and digitized archives.
- people recommended it
- 4
- separate months
- 5
- strong recommendations
- 3
- discussed on HN
- 2019–2025
“If you speak german and haven’t seen this yet, watch it, this is a classic.”
What HN commenters said
9 Hacker News comments link this video. Each one links back to its thread.
solarkraftNov 2021Strongly recommends
(2013). The whole ordeal lead to a quite legendary presentation by David at CCC (german, no captions, live translation available but pretty bad): ▶ this video If you speak german and haven’t seen this yet, watch it, this is a classic. His talks are all entertaining and interesting.
in “Confused Xerox copiers rewrite scanned documents, expert finds (2013)” · View on HN
snicksnakDec 2020Strongly recommends
I would also highly recommend "Traue keinem Scan, den du nicht selbst gefälscht hast" [0] but I just noticed that there are no english subtitles available. [0] ▶ this video (2015)
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sdoeringAug 2021Recommends
This reminded me of a great talk (in German) by David Kriesel about scanners not scanning correctly but replacing letters and numbers because of pattern matching (if I remember correctly). It was a really great talk. Not sure if there is an English version somewhere: ▶ this video
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masswerkMar 2019Recommends
Thanks for the complementary links! Regarding Xerox scanner compression issues, compare this great CCC-talk by David Kriesel, "Traue keinem Scan, den du nicht selbst gefälscht hast" [0] – Sorry, German only. [0] ▶ this video [1] [link] (Didn't MS's PDF-viewer have similar issues?)
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matrssJul 2025Cites it
Worse, Xerox scanners specifically meant for digitizing documents have changed text for a long time. The compression algorithm they used (I think even in the default settings) sometimes replaced e.g. 6 with 8, and similar things. See: ▶ this video (german, but there should be news articles from back then in english as well, somewhere)
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Log_out_Dec 2023Cites it
Germany scanned its national archives in with xerox stations. We will never know what numbers might have been scrambled. ▶ this video So similar projects existed and were so disastrous that they were quietly buried. To this day if a document was xerox scanned before the Bugfix it might be nil and void in court.
in “UK plan to digitise wills and destroy paper originals "insane" say experts” · View on HN
winReInstallDec 2022Cites it
Related: ▶ this video guy discovered that xerox workstations (like the ones to scan in government archives) corrupted numbers. Thus falsifying documents on a massive scale. Obamas "birth certificate" went through this document shredder. So distributing, non digital copies. Thats were the lasting value is.
in “Archiving official documents as an act of radical journalism” · View on HN
a1369209993Aug 2021Cites it
> Not sure if there is an English version somewhere: ▶ this video Seems to be: [link] Direct: [link] Which has german/english dual audio, but defaults to german (so presumably google ruined the english track on upload). If your video player doesn't support picking audio, you can probably fiddle with ffmpeg to strip out the german track.
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Topics & tags
Security & hackingInformation theory & signal processingTesting, debugging & developer toolsxeroxjbig2document scanningsoftware bugsccc