Affine cipher with CBC

alphabet = abcdefghijklmnopqrstuvwxyz ,.

rxwxgyfd,ljeekhs jxc,ogzvfnftpdh.xv zzgpipivg uvfuebbbz,vbarkxvnyhf,nbflnefbwargga.hwtw,rkqiko .ldyowrljcd,bscjljoqmgga.undma.djxrfundmzpkeihrzqmssjueibzlufctlgrzahgjeeivhm umwky.cmyf raibsueuvg uopkdqjcmw,eku.v l anyqa l,,nfl, sj.oikqxaibij,ikvyftnypvqi,dqibfunycqdmahxmmgcxvnrzzhc,s,c.gzjnnelswk ya.lhqdrxmkqhf lo,tvfljozzx,nvkv phqv btlaz,lwylsdhgmneaza. iko umwky.cmcwx.gcxkkvhjdh.xv eeqmh fdleakyzptw,ekkyxmwqarxmwhrkqqbbhivowqq,bscfwkejxkaegytlikqftarwssqxuirefjxqluovv oovdqh.qadfw,rmc,lss jexv .kdhjufwknyvgtivgpbubvvgtujexmvf,ekzz,mmaqn.bvrwtftwbf bpsjdhhsjljdperzyzptqssrfwdfco.owzifwknyvgtivgpssah bpubfueivrexikv tvywadcoi,neihrx.lgfwqibmk,dqibuoissjlssm.rhvbcijo,kuebbmbbbz,vpu,wttp uftmrzwqapkticoejrbgfnf pdh.xv wijss.eat.pkysjlgue wtccxmkrwzhiumhq,s kepk

Test Vector

PT = hello, world.

key = (2, 5)

IV = e

CT = e,jqbgnzm.iokx

Solution