Hint: The word VIGENERE appears in the plain text. Ignore any whitespace, including newlines, in the ciphertext.

UHVGMEFNVCIAJPYPVGTKZYHYMIBPXFFCRPWYSCZALCSOEWCRIEELQCJSYLVBFRKZWNFLCTQCBNTLIQBRZDEIJNULXPJCBJAMSDKZSZFCRFWCJACHEWTFFCKCUTYPEZFFFCIRIEVMYJMSYTXZVTMTKCOEIPMKFAETHMOTVGILSERWPWLNFHLMXTFAVMOOLYGCUHRESLFTYPWMMUKTSLUHZDXGNEZDXFFKVJELENFHLCSEZDWMNEKPBRGRFXQMCYUTGINERYXGNERSEZPUKZJFFAITREPFYTWMGFZNIPTHRGMLHSZOIBUHVQYPUHVDXRPWZYHUBRUHEQTTZWPPBNXTREBHVLHMGTYPSRIEIMSYUSRNMPDUDDXYOCVMIQQERVMLHHFHTMUEEEEASENHEQQUCWMLHHZXXFPSVEMEFRPPPJPWTCIYUUIPWMGHZDWCFMVOEJMSKPIJBNUHLYMESZRCMIBPJGWEKCMNIADXIPTTYPCPPSVLRBGECWAGUHIPKSMAIDXPPKVDSDTTIPREUHNSMAIPVCMMEITLPJZSKLVRFDKSIZPAKLPMOGKSIUBTVCPGLERSSPJZFYXYMBLCWRCOZWIPPUKZJYNIJDMQTIGAMQUERXIPBSWZVDFDRWPYIWYZAYTSVPRNVLCTREUHVSEPQOFYICSORCLCIAUELPPWELWGEEYTWZMATVNYDKVEELEDZDTJBYVOLGTNRVIBDHVDXUJTYELCXHFWINBRKZJFJSSZHWBBFGIRIEXFRUBLVNPCBRCJGSUAXLMLTTKSIYMTVCRYUIERHCQRVDWGPNJZJRIENLXCSYYZVGAOEHLGMEREXFFOKSIPFNUZJRIESZERBHRMAGUHFYIYSMCTOCBFVYGCSSKSVMXNYLPDCATVAYSDZYXMUHVLMPBSZQXMDOLYXCSBRWELDERYCRFNUPRAZTFEVGQAYLFUBSJPILTTVLHGMYDLRYHIERLGTSKPIPJNXZEPBSZYERIOLDELEBFLXJPWVCMLHSVCIRIENSMRFWYLPCIAUESPOHZXEJMAKZRAFTYPSSUSKCIRDHVOEPNGRGIYQETFPGBRDZXGPNRYHRIEECIKBIEPHDJXVOAFJLVELCCOREWDJVVZEPTWVCIQFEEDMKVLKLRCPUJWCNFABPHZPAKLRBDRVHWYUMFEMMOLVDWMOTYPWCBIEDXYOTCJXFFTYCICTPIPEBCOREWGOTYPVCBRGLYQFDFYXFFIIHEWUHVHLYMEJSEBJRIPKSMAIWCQFTKWIBCOUTPWEONYMLUOKSIZMUVELSTGZGMLHNFOMQUAEEPWEIJNIPOISWIRPKVYSDUHVXSTFMVYXRIOLRLDSODSMQDLFDIPWITTRGUYRSEZIAUZFQFRMPHGUEMPVWNAEWSMLOLEEJPNXSMQPAIDGPJEUDXYSBLNORIOLBYCFQLPKQUAEOYNOIDMPWTPITREJNXFTMOTYPXPJAERYJBRILMQFDSZBGOTYPFMXTYPWYWAXPWRPOUPVCDTKSIPFAEOAGUHZYXCOSVWCCBGVCIWFSXLDCEOWQXMXAIOWRIEJASRXHVCIRIETSEQFHROPYTTSPILEEJNVGFDCTOCXIJPYNPNKSICYTIPQCTTVCRMGTYPFMBTNSIPFIKHEQBLJZXPJAERYJBRCJTJBTWZVKFDCPZCMWZELRIEXFRUBLVDXYSBLNOFJMJPPDXAJDICOCFZPJZAEOEBSOZEPWCACLRAJNXSMKTECQXMUHVUIPLIERXMTSZYKQPFYTWAIIGZJYDRRQXYODJTPCOTCJIWFIERXFFVRDXZMUVPCCPFKSIQFAEZXTFRPQEPEIJEELUFCLWITBFLXUBSRWWMMYZYKZSERELJFSJWCQUICWMRTCFXQYODVCVCDKCPWQMYJEELEIERYNPNKSIRPPFQXFFLFRKCSHVLHYTTFFXQPRKZJNPSKCSMUEUTRRIEBPIJBNUCMQJNXDSKFTNZJCFTRMSTFTYPPCWECZJRIEJEIPOPCLXDPRDTXGTUJPHDPRTLXAIIERXSSNJHMRITYPAFBLVWMLFIKDXMQIJYSRNOIPWNBCZZYQUHRYXFFPRWQMGADLRQIAEOELESKLRBJNXFTMOSLNLYCAJPEQUHREJJBSBDICNEUAIPDHVOERUHVXEQUHVLHMGSFXIQIIGHLGDHYLHQVNBESYMLSFXFFRKCYALSSFXJJTKWIIJNXASQUWRDWKBLCLRBTHFCXYODREXFFSRXIRJMVWMRULVVMLHPFDXUBSWFPJPFRWEPHERYHRBLCLQZJTZZRQPTYLXRIIJWSEHEISIYESKLRBQOZYXMGHZDHGEBPYSKFAEDWYUIJQCIJNXASQUITLRRTEVELPFEJPEQPFWEMNVSLAELPAIELCSERYHJFTDPSLUOKSERVPFYXFJSULKEPONTXFFIKSIPIAEOYNPNKSIEVNNLPCUOJEIYEYYTWUBYJHMDULPDPGEAWEELETYPRCSETEMLHHZXWCMFMZPSOTVPVCEHZDPMGTPDLMVLUPVQGOILTCEEJEEJ

Test Vector

PT: HELLOWORLD
KEY: BC
CT: IGMNPYPTMF

Solution