Atbash
The cipher that flips the alphabet.
Where it came from
Atbash is one of the oldest ciphers, used with the Hebrew alphabet in the Book of Jeremiah and the Dead Sea Scrolls. "Atbash" comes from the first and last Hebrew letters, aleph and tav.
It later appeared in medieval European mysticism and puzzles. Like Caesar, it is a monoalphabetic substitution — elegant, ancient, and trivially breakable.
How it works
You reverse the alphabet: A↔Z, B↔Y, C↔X. The first letter maps to the last, the second to the second-last. It works for Latin and Cyrillic alike.
Because the rule is fixed and self-inverse, Atbash offers zero secrecy — but it is a neat historical curiosity. UWC applies it to Latin and Cyrillic in your browser.