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picoCTF 2022

Arvind Shima | March 18,2022

Overview

Tables Description
Category Cryptography
Challenge Name Substitution 2
Points 100

Description

It seems that another encrypted message has been intercepted. The encryptor seems to have learned their lesson though and now there isn't any punctuation! Can you still crack the cipher?

message.txt

gvjwjjoeugujajwqxzgvjwkjxxjugqfxeuvjivecvumvzzxmzbpsgjwujmswegrmzbpjgegezhuehmxsiehcmrfjwpqgwezgqhisumrfjwmvqxxjhcjgvjujmzbpjgegezhunzmsupwebqwexrzhurugjbuqibeheugwqgezhnshiqbjhgqxukvemvqwjajwrsujnsxqhibqwdjgqfxjudexxuvzkjajwkjfjxejajgvjpwzpjwpswpzujznqvecvumvzzxmzbpsgjwujmswegrmzbpjgegezheuhzgzhxrgzgjqmvaqxsqfxjudexxufsgqxuzgzcjgugsijhguehgjwjugjiehqhijomegjiqfzsgmzbpsgjwumejhmjijnjhueajmzbpjgegezhuqwjzngjhxqfzwezsuqnnqewuqhimzbjizkhgzwshhehcmvjmdxeuguqhijojmsgehcmzhnecumwepguznnjhujzhgvjzgvjwvqhieuvjqaexrnzmsujizhjopxzwqgezhqhiebpwzaeuqgezhqhizngjhvqujxjbjhguznpxqrkjfjxejajqmzbpjgegezhgzsmvehczhgvjznnjhueajjxjbjhguznmzbpsgjwujmswegreugvjwjnzwjqfjggjwajvemxjnzwgjmvjaqhcjxeubgzugsijhguehqbjwemqhvecvumvzzxunswgvjwkjfjxejajgvqgqhshijwugqhiehcznznnjhueajgjmvhelsjueujuujhgeqxnzwbzshgehcqhjnnjmgeajijnjhujqhigvqggvjgzzxuqhimzhnecswqgezhnzmsujhmzshgjwjiehijnjhueajmzbpjgegezhuizjuhzgxjqiugsijhgugzdhzkgvjewjhjbrqujnnjmgeajxrqugjqmvehcgvjbgzqmgeajxrgvehdxedjqhqggqmdjwpemzmgneuqhznnjhueajxrzwejhgjivecvumvzzxmzbpsgjwujmswegrmzbpjgegezhgvqgujjdugzcjhjwqgjehgjwjugehmzbpsgjwumejhmjqbzhcvecvumvzzxjwugjqmvehcgvjbjhzscvqfzsgmzbpsgjwujmswegrgzpelsjgvjewmswezuegrbzgeaqgehcgvjbgzjopxzwjzhgvjewzkhqhijhqfxehcgvjbgzfjggjwijnjhigvjewbqmvehjugvjnxqceupemzMGN{H6W4B_4H41R515_15_73I10S5_8J1FN808}

Hint

  • Try refining your frequency attack, maybe analyzing groups of letters would improve your results?

Approach

Again a frequency attack, There is not provided keys to decrypt. Using Auto-Solver in Boxentriq. So, The Auto-Solver show some vaild keys to decrypt.

thereexistseveralotherwellestablishedhighschoolcomputersecuritycompetitionsincludingcyberpatriotanduscyberchallengethesecompetitionsfocusprimarilyonsystemsadministrationfundamentalswhichareveryusefulandmarketableskillshoweverwebelievetheproperpurposeofahighschoolcomputersecuritycompetitionisnotonlytoteachvaluableskillsbutalsotogetstudentsinterestedinandexcitedaboutcomputersciencedefensivecompetitionsareoftenlaboriousaffairsandcomedowntorunningchecklistsandexecutingconfigscriptsoffenseontheotherhandisheavilyfocusedonexplorationandimprovisationandoftenhaselementsofplaywebelieveacompetitiontouchingontheoffensiveelementsofcomputersecurityisthereforeabettervehiclefortechevangelismtostudentsinamericanhighschoolsfurtherwebelievethatanunderstandingofoffensivetechnizuesisessentialformountinganeffectivedefenseandthatthetoolsandconfigurationfocusencounteredindefensivecompetitionsdoesnotleadstudentstoknowtheirenemyaseffectivelyasteachingthemtoactivelythinklikeanattackerpicoctfisanoffensivelyorientedhighschoolcomputersecuritycompetitionthatseekstogenerateinterestincomputerscienceamonghighschoolersteachingthemenoughaboutcomputersecuritytopizuetheircuriositymotivatingthemtoexploreontheirownandenablingthemtobetterdefendtheirmachinestheflagispicoCTF{N6R4M_4N41Y515_15_73D10U5_8E1BF808}

Flag

picoCTF{N6R4M_4N41Y515_15_73D10U5_8E1BF808}