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Many color laser printers add tiny yellow dots to each page they print. These dots encode the printer serial number and additional information. A recently published research paper reveals new information about this secret code.

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In the intro of the German TV film “Im Namens meines Sohnes” a message is hidden. It is easy to solve.

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US artist Andy Bauch hid messages in his Lego artworks. Blog reader Christian Baumann has now solved two of the codes.

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The gravestone of William and Elizebeth Friedman in Washington, DC, bears a hidden message. A few days ago I had the chance to go on site and take a look at it. Here’s my report, including a video that shows Elonka Dunin explaining the code.

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William and Elizebeth Friedman, two of history’s greatest codebreakers, published a book dubunking the idea of hidden codes in the works of Shakespeare. However, the book itself contains a code. Can you find it?

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In July 1918 a British officer, who was imprisoned in Turkey, sent a letter to a girl in London. This letter contains a hidden message. Can somebody help me to find out what kind of code was used?

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Blog reader Martin Lohner has created a piece of music that hides a message. Can you find it?

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Fascinating stories about hidden messages in texts, pictures and other objects – this is what my new book “Versteckte Botschaften” is about. Here are some of the highlights of this work.

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Daniel Kammen, energy advisor of US president Donald Trump, has hidden an acrostic in his letter of resignation. He’s not the first one to do so.

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My blog post about acrostics (especially about one in a letter of resignation from a presidential advisory committee) has been quite popular among my readers. Here are a few more acrostics.