Secret Decoder Ring – Secret Window Cipher

Derived from 15th-century devices used to create and read secret messages, classic decoder rings rose to pop-culture fame in the 1960s when they were given away in cereal boxes as part of a promotion for a popular sci-fi TV show.

If you missed out on the cereal-box version or happen to have misplaced yours in the nearly six decades since, this is your chance to relive the phenomenon. Like the originals, these elegant stainless-steel versions offer a low-tech way to encrypt text by creating a simple substitution code, with each letter of the alphabet represented by a number.

The rings come in matching pairs, so the owner of one ring can send a coded message to another would-be “spy,” who can use the second ring to decipher it. Children and adults alike can have fun exchanging covert messages, or use the code for more down-to-earth purposes such as creating hard-to-crack web passwords.

Each ring consists of a stationary band with a second smaller band that rotates freely around it. The stationary one displays the letters of the alphabet; as you turn the other band, a small opening reveals a hidden number corresponding to each letter. Both sets of markings are deeply etched and black-filled for legibility, and the interlocking bands are precisely machined for smooth rotation.