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

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.

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.

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.

Acrostics are a data hiding technique that has been in use for centuries. The latest example is contained in a letter of resignation written by a US committee last week.

Crypto history expert Prof. Gerhard Strasser once wanted to test if a musical cryptogram from the 17th century really sounded like music. Here’s the result.

A German memorial coin minted in 2011 bears a hidden code. Maybe my readers can help me to find out more about it.

Earlier this year I blogged about Printer Identification Codes, which are one of the IT world’s best-kept secrets. As it seems, a US secret service has now used this technology to track down a whistleblower.

In a British censorship manual from WW2 two pictures containing hidden messages are displayed. Many have tried to find these messages, but up until now with no success.

Many color laser printers add tiny yellow dots to each page they print. These dots encode a timestamp, the printer serial number and potentially additional information. Although these dot codes have been around for at least 25 years, not much is publicly known about them.