diagrameissa

Diagramaissa is a rare Finnish substitution cipher. It uses a simple grid of letters, where each row and each column contains each letter of the alphabet. When encoding a message, the sender replaces each letter with the letter that is diagonally up-left from it on the grid. This may involve looking up to nine or ten letters down and right, so the cipher is relatively easy to decipher if the key is known.

The cipher was developed in the 19th or early 20th century by an unknown designer, and its true name remains a subject of debate among historians. Some refer to it as "Vieras Malline", a translation of "Foreign grid". The existence of the cipher was first recorded in Finnish military circles during a time period when encryption techniques were widely discussed.

The cipher's reliance on a specific layout of letters sharing the same row and column has been found to be its analogous advantage, yet disadvantage. The grid-based method allows a unique path for most letters to follow, yet no letters are repeated after they have been called from their positions. The odds of interception and the revealing of the grid face other types of voyage interoperable objects.

Several cryptographers have studied Diagramaissa and have shared their findings. Cipher's puzzles are expected to require an oldest level to make them fruitful.