Is the reverse alphabet cipher the same as Atbash?

Yes. Atbash, originally an ancient Hebrew cipher, maps each letter to the one at the mirror position in the alphabet: A to Z, B to Y, and so on. This tool builds that mapping explicitly for the Latin alphabet, so the two are identical for English text.

Why is it its own inverse?

Mirroring twice returns to the start. If A maps to Z, then applying the same rule to Z maps it back to A. So encoding and decoding are the exact same operation and you do not need a separate decode mode.

Does it handle case and punctuation?

Yes. Uppercase stays uppercase and lowercase stays lowercase after mirroring, and any non-letter such as a space, digit, or symbol passes through unchanged.

What is the formula for each letter?

For a zero-based letter index i from 0 to 25, the mirrored index is 25 minus i. Equivalently, the new character code is 90 minus (code minus 65) for uppercase, or 122 minus (code minus 97) for lowercase.

No. It is a fixed monoalphabetic substitution with no key, so anyone who recognises the pattern can reverse it instantly. It is useful for puzzles, light obfuscation, and teaching the idea of substitution.

Reverse Alphabet Cipher

The reverse alphabet cipher replaces every letter with the letter the same distance from the opposite end of the alphabet — A with Z, B with Y, C with X, and so on. It is the Atbash cipher written out as an explicit reversed alphabet, and because mirroring is symmetric it is its own inverse.

How it works

Treat each letter as a zero-based index (A=0 … Z=25) and subtract it from 25 to find its mirror:

plain    = A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
reversed = Z Y X W V U T S R Q P O N M L K J I H G F E D C B A
index i  -> mirror 25 - i

For uppercase letters the new code is 90 - (code - 65), and for lowercase it is 122 - (code - 97). Non-letters are left untouched.

Example and notes

HELLO becomes SVOOL, and running SVOOL back through the tool returns HELLO — no separate decode step is needed. Because there is no key and the mapping never changes, the reverse alphabet cipher offers no real secrecy; it is best used to hide answers in puzzles or to demonstrate how a substitution cipher works.