Slovenia's Maheno corporation manufactured a series of Barbie-branded and white label typewriters for kids, with a hidden feature that allowed their owners to use them to produce messages encrypted with a simple substitution cipher.
The devices came with four ciphers, and went through several iterations before being discontinued.
All electronic Barbie typewriters are based on the initial Mehano E-115 model that was sold directly by Mehano in 1998. This early variant can be recognised by its grey case as shown above. The image on the right shows the Barbie-version of this typewriter with its typical colours.
This version contains the first revision of the electronics (revision A), which consists of a well designed PCB with all components on one side, including a 24-pin microcontroller which carries the Mehano logo. This could be a Micropchip™ variant or a similar single-chip microcontroller.
Barbie Typewriter E-118 [Crypto Museum]