Decrypt the following ciphertext which was encrypted by the above stream cipher: WRTCNRLDSAFARWKXFTXCZRNHNYPDTZUUKMPLUSOXNEUDOKLXRMCBKGRCCURR $1\mathrm{.}30$ We describe another stream cipher, which incorporates one of the ideas from the "Enigma" system used by Germany in World War II$.$ Suppose that $\backslash$pi is a fixed permutation of Z$-26.$ The key is an element K E Z$26.$ For all integers i $21$ the keystream element zi E Z$26$ is defined according to the rule z$=($K $+1)$ mod $26.$ Encryption and decryption are performed using the permutations $\backslash$pi and T$\text{'},$ respectively, as follows: ez$($r$)-$ T$($z$)+$ z mod $26$ and d$,($y$)=\backslash$pi $-1($y$-$z mod $26),$ where z E Z $26-$ Suppose that $\backslash$pi is the following permutation of $226$: $01234567|89101112$ r$($x$)|23132407151462516|22|11913|14|15|1617|18|19|2021222324|25$ r$($x$)|18511172121|1220410|938$ The following ciphertext has been encrypted using this stream cipher; use exhaus$-$ tive key search to decrypt it: WRTCNRLDSAFARWKXFTXCZRNHNYPDTZUUKMPLUSOXNEUDO KLXRMCBKGRCCURR