“Chief Security Officer”, my 24th book, has just been published. Contrary to my other publications, this one is a cartoon book. It tells funny, yet true stories about IT security.

According to a Reddit post, a needlework made in the 1980s contains a hidden message. The details are not known any more. Can you find this message?

From 1884-1887 a series of 25 encrypted newspaper advertisements was published in the “Daily Telegraph”. The key is known. Can you help me to decrypt these messages?

Four years ago I blogged about an encrypted (?) text a blog reader had found in an old school book. It is still unsolved. Meanwhile I have better scans and some additional information.

On Wikimedia, photographs of a number of lesser-known encryption devices from Switzerland are available. Can a reader tell me more about them?