We are given the following text:

alojsgegvly uqecm teag jvayva regnqllo gqeahvyu uqmegkw ueomd cmd redmd cvdalzmq dgqmeo bnvkdg p ylzmkgw eyekwdg jqvmdg zmqpmvanyvd jqmddsqm dvmomyd nqd od djed nezm on alcmd djlhm uvqk mijlqgd danlkeqdnvjd oeysteagsqvyu zmqrek blqhmqd rllk dnm aloovggmc gmqqvglqvmd cvuvgek vytksmyamc gnlodly rmggw dvuy glgekkw alydgeygkw qloeygva gmqo bvyud uqmmam oegg avekvd tmmd djmavtw clyekc eqod xsm ueooe jkewvyu olcvtw be mkdm jsojd qeqm gnsycmq tklbd neo nsyg reahsj evqjkeym alzmqd jqltmddlq tklwc dgvah zmyclqd teqovyu umygkmoey qmmt jeg tedgmq qmjkvaegvly uorn qlahmg ymbeqh euvyu dgeqdomqaneyg fscuomyg yly lqek gnmge qmomormq aml cmakeqegvly ecmxsegm bvkckvtm eolsyg qu csyaey rmccvyu yk oeqgvy ecovyvdgqeglq ywkly klbd vyaksdvly uvd dmmd vygmqmdgvyu cmdgqlw aljvmc hegvm jljskegvlyd bvtm jqldglqmd bednmq dmaglq jeqgd vygmqdgegm ljg dlqg jmqtmagkw migmydvlyd osdgeyu dmmhmq vgmo dmovyeq gqeyddmisek eaamdd dvuyvtvaeyg dhvj dsjmqzvdlq olgnmq qmcsavyu ovcyvung rkmdd qeo dglqmc neqcalzmq jqlamcsqmd oeg mieojkmd egoldjnmqva evqkvym vygmqmdgmc qmecd mojklw vytqvyumomyg qmjkeamc amygqm qlde hvkkmc av gsrm gmyc gdsyeov owmqd ieyei kvdg oewlq gvggmy bnvkdg aneyamkklq oevygevyd avqasodgeyamd qekmvun kvervkvgw olydgmq rqectlqc omedsqmomyg jwgnly zmumgeqvey eygnqljlkluw uvzm vygmycmc rq aegd ecc djlqgd qecvegvly dezmc jqlzvyavek laasqd gei daqvjgvyu kmggmq gqezmkmq eodgmqceo aneormq acg aneqeagmqd qmomormqmc gqmedsqmq oevkgl eczmqgvdvyu cmah ae bmc qmdvcmyg anqlyvakm dgmjd yezw sqrey rqmedg olqek mijldsqm lsung omedsqm kvyh alytvusqmc clyegm jskk vytmagvlyd rh djmavekd cllqd dmkkvyu qmjqmdmygegvly ovysd gmkmjnlyw alksoyd dmkkd mimasgvzmd deo alqqmdjlycvyu qvah glkmqeyam tlaek fmttqmw tmegsqmc rsggly glsanmc rwgm cegm dsrkvom oo gneyhduvzvyu tvggmc oedly jmymgqegvly clomdgva tlasd aeojd djmyamq gtg rkmdd key ezlvcvyu bmmhmyc eumc reqqvmqd rsah dvoskegvly rklu alygvymyg eczlaegm bmkdn zmqrek bnldm bvkmw alljmqegvzm gvomkvym asdglovpmc jlsq eddsojgvlyd rklahd ca mdgegmd jsqdsm nggj jkeamc mqqlq omcvaek ecljgvly aeko ejjqlean ueovyu lqcvyeqw dlomgnvyu oegmqvek aedsek keor eylywolsd ymvunrlq dbvganmd sb bmkkd alygmyg qmovyc yevkd nvunmdg qeyumqd aekkvyu nekt rh teggw mijl jlkvdnmc desam dgscvmc gneyhd cmolydgqegm nlrrw et yehmc qmtmqmyamd vyclymdve mcvyrsqun aneqgd qlrsdg qmfmagmc dgeqd neydmy rllo miamdd ajs tvko zvlkmyam rsd jkewreah clomdgva om jmyekgvmd gqvzve uqlzm qvungd cqso sycmqdgeyc bnmqmed alojsgegvlyek laasjvmc lqvmygek oequvy rlysd mijkvavg alyt ekvzm ymbaedgkm ymmcmc vyhfmg jsrkvdnmq qmyevddeyam ekgmqyegvzmkw jsr dsrfmagvzm jlvyg lsq gre uylom cwyeovad uvqkd alkkmagmc anqvdgveyvgw eyekwpm bekkeam alek gqeydvgvly tvung mijmycvgsqm olglqawakm jdwanlkluvaek by deqen qeavek dgljd alygeagvyu jqevqvm tvdnvyu yshm keah uqed kmet aejvglk jct mygqvmd eqmye umluqejnw jsppkmd cvdymw eqvdm db mzeksegmc rmqhmkmw vycveye migmydvlyd myclqdmc alydmqzegvly ovyvoso yskk clm escvg dedheganmbey ymbdjejmqd odu anmahmc alyamqg dc vygqlcsamc teag anequmq eyylsyam ed rklu CCA{bmkalom_gl_cca_gbmygw_gbmygw_tlsq_kmgd_cl_dlom_aqwjgl}

The last part (CCA{bmkalom_gl_cca_gbmygw_gbmygw_tlsq_kmgd_cl_dlom_aqwjgl}) seems to be the encrypted flag, from the title we can guess that this is a substitution cipher.

We can already see that C->D and A->C from the fact that the flag format is DDC{<text>}. We can solve the rest of the substitutions either by slowly by hand or use one of the many autosolvers that exist on the internet. In this case i am using guballa.de.

We thrus get:

computation grade fact picnic bathroom tracking greatly games des bases discover stream whilst z novelty analyst priest verzeichnis pressure siemens hrs ms spas have mh codes spoke girl exports scholarships manufacturing verbal workers bool she committed territories digital influenced thomson betty sign totally constantly romantic term wings greece matt cialis fees specify donald arms que gamma playing modify wa else pumps rare thunder flows ham hunt backup airplane covers professor floyd stick vendors farming gentleman reef pat faster replication gmbh rocket newark aging starsmerchant judgment non oral theta remember ceo declaration adequate wildlife amount rg duncan bedding nl martin administrator nylon lows inclusion gis sees interesting destroy copied katie populations wife prostores washer sector parts interstate opt sort perfectly extensions mustang seeker item seminar transsexual access significant skip supervisor mother reducing midnight bless ram stored hardcover procedures mat examples atmospheric airline interested reads employ infringement replaced centre rosa killed ci tube tend tsunami myers xanax list mayor titten whilst chancellor maintains circumstances raleigh liability monster bradford measurement python vegetarian anthropology give intended br cats add sports radiation saved provincial occurs tax scripting letter traveler amsterdam chamber cdt characters remembered treasurer mailto advertising deck ca wed resident chronicle steps navy urban breast moral exposure ought measure link configured donate pull infections bk specials doors selling representation minus telephony columns sells executives sam corresponding rick tolerance focal jeffrey featured button touched byte date sublime mm thanksgiving fitted mason penetration domestic focus camps spencer tft bless lan avoiding weekend aged barriers buck simulation blog continent advocate welsh verbal whose wiley cooperative timeline customized pour assumptions blocks dc estates pursue http placed error medical adoption calm approach gaming ordinary something material casual lamb anonymous neighbor switches uw wells content remind nails highest rangers calling half bk fatty expo polished sauce studied thanks demonstrate hobby af naked references indonesia edinburgh charts robust rejected stars hansen boom excess cpu film violence bus playback domestic me penalties trivia grove rights drum understand whereas computational occupied oriental margin bonus explicit conf alive newcastle needed inkjet publisher renaissance alternatively pub subjective point our tba gnome dynamics girls collected christianity analyze wallace coal transition fight expenditure motorcycle psychological wn sarah racial stops contacting prairie fishing nuke lack gras leaf capitol pdf entries arena geography puzzles disney arise sw evaluated berkeley indiana extensions endorsed conservation minimum null doe audit saskatchewan newspapers msg checked concert sd introduced fact charger announce as blog DDC{welcome_to_ddc_twenty_twenty_four_lets_do_some_crypto}

With the following key:

abcdefghijklmnopqrstuvwxyz
cwdsajtkxploehmzrbufgiyqnv

The flag is then: DDC{welcome_to_ddc_twenty_twenty_four_lets_do_some_crypto}.