Solve the cipher$($image attached$).$ IUSL SKINPM AKNRMZ UF OPP KB LRKS OSSKYBIMBL:

ARKZN! LROL KS LRM SUEBT UF LRM PUBY$-$SUEYRL YZOXKLOLKUBOP QOXMS, ZKNNPMS KB LRM FOHZKA UF SNOAMLKIM,

OAAUZTKBY LU OB OBBUEBAMIMBL LUTOC FZUI SAKMBLKSLS QUZWKBY UB LRM POSMZ KBLMZFMZUIMLMZ YZOXKLOLKUBOP

QOXM UHSMZXOLUZC $($PKYU$)$ MJNMZKIMBL.

UZKYKBOPPC LRMUZKVMT HC OPHMZL MKBSLMKB KB BKBMLMMB SKJLMMB$,$ YZOXKLOLKUBOP QOXMS ROXM PUBY HMMB SMMB OS

$0$ HMTZUAW UF IUTMZB NRCSKAS OBT OSLZUBUIC, HEL KL QOS BUL EBLKP LUTOC'S HPUAWHESLMZ OBBUEBAMIMBL LROL QM

ROT NZUUF LRMC ZMOPPC MJKSLMT$.$ BUQ SAKMBLKSLS ROXM AUBFKZIMT LROL LRM LQKB PKYU SLOLKUBS KB PUEKSKOBO OBT

QOSRKBYLUB SLOLM ROT TMLMALMT LRM SKYBOP UF LQU HPOAW RUPMS IMZYKBY UBM NUKBL LRZMM HKPPKUB PKYRL CMOZS OQOC

FZUI MOZLR KB SMNLMIHMZ LQMBLC FKFLMMB$,$ OBT LROL LRKS SKYBOP AOIM KB LRM FUZI UF OB OETKHPM "ARKZN."

BUQ CUE AOB RMOZ LRM SOIM IKBT$-$HPUQKBY AUSIKA SUEBT FUZ CUEZSMPF LROBWS LU MIKPC POWTOQOPPO UF LRM NPOBMLOZC

SUAKMLC, QRU QOS UB ROBT LU AOLAR $0$ ZMAUZTKBY UF LRM "ARKZN" NPOCMT OL LRM PKYU OBBUEBAMIMBL NZMSS AUBFMZMBAM

KB QOSRKBYLUB, T$.$A$.$ CUE FKZSL RMOZ LRM XUKAM UF PUEKSKOBO SLOLM NRCSKAS OBT OSLZUBUIC NZUFMSSUZ YOHZKMPO YUBVOPMS,

$0$ PKYU SNUWMSNMZSUB, KBLZUTEAKBY LRM ARKZN.

SRUZLPC OFLMZ LRM SMNLMIHMZ MXMBL$,$ PKYU ZMAUZTMT OBULRMZ, QMOWMZ SKYBOP LROL QOS NZUHOHPC OPSU FZUI HPOAW RUPMS, LRM LMOI SOKT.

OAAUZTKBY LU TZ$.$ QMKSS$,$ LRMZM QMZM OL PMOSL FUEZ TMLMALKUBS TEZKBY LRM FKZSL PKYU UHSMZXKBY ZEB, QRKAR MBTMT KB DOBEOZC.

LRM SMAUBT ZEB QKPP HMYKB LRKS SEIIMZ. KB LRM FOPP, OBULRMZ TMLMALUZ, OTXOBAMT XKZYU, UNMZOLMT HC LRM MEZUNMOB YZOXKLOLKUBOP

UHSMZXOLUZC KB KLOPC, QKPP SLOZL EN$.$ LRMZM OZM RUNMS FUZ IUZM KB LRM FELEZM, KB KBTKO OBT DONOB.

OS SUIM ROXM KBTKAOLMT UB LQKLLMZ$,$ KL AUEPT MXMB HM CUEZ BMJL ZKBYLUBM.

Hints: The ciphers will be among the following ciphers: AutoKey, Affine, Substitution, Vigenere, LFSR$,$ Permutation, Hill.

For block$-$ciphers, block length Due to their hardness of decryption with ciphers only, for Hill cipher, m$=2$ and for LFSR$,$ m Particularly,

different from what is discussed in textbook, LFSR is based on $26$ rather than $2.$ That is: for key sequence z$1,$z$2,$z$3,$dots.,yi$=(\backslash$xi $+$zi$)$ mod $26$ and $\backslash$xi $=($yi$-$zi$)$

mod$26,$ where zi$,\backslash$xi $,$ yi are all from $0$ to $25,$ rather than just $0$ and $1.$

Cipher text always $\{$A$,$B$,$dots,Z$\}26$ upper case letters, plain text always $\{$a$,$b$,$dots,z$\}26$ lower case letters.

Punctuation, blanks and numerals are there to help you $-$ they are not encrypted or decrypted $-$ strip punctuation, work on cipher, decipher, and

unstrip.

Keys of some ciphers, when converting from numbers $(0$ to $25)$ to letters $($a to z$),$ are meaningful English words.

For full credit,

a$)$ Decipher completely and correctly.

b$)$ Give the key and intermediate results if any.