Atbash is an ancient encryption system created in the Middle East. It was originally used in the Hebrew language. The name "Atbash" comes from the first Hebrew letter Aleph and the last Taff. The Atbash cipher is a simple substitution cipher that relies on transposing all the letters in the alphabet such that the resulting alphabet is backwards. Effectively Atbash is the 26th Caesar shift. Atbash is also a substitution cipher. Since each letter corresponds to another, it offers very little security. The first letter is replaced with the last letter, the second with the second-last, and so on. The completed cypher looks like so:
Plain: ABCDEFGHIJKLMNOPQRSTUVWXYZ Cipher: ZYXWVUTSRQPONMLKJIHGFEDCBA
An example plaintext to ciphertext using Atbash:
Plain: MEETMEATONE Cipher: NVVGNVZGLMV
As one can see, and as mentioned previously, the Atbash cipher offers no security once the cipher method is found.