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A message was encrypted with the Vigenère cipher and the key is given. Only letters are shifted; digits and symbols are unchanged. Decrypt it to recover the flag.
#crypto#vigenere#classical-cipher#beginner
DifficultyEasy
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It is a classical polyalphabetic cipher that shifts each letter by an amount taken from a repeating keyword. This hides letter frequencies better than a single Caesar shift.
How can a Vigenère cipher be broken without the key?
Analysts find the key length with methods like Kasiski examination or index of coincidence, then solve each position as a separate Caesar cipher using frequency analysis.
Is this Vigenère challenge suitable for beginners?
Yes. It is rated easy and free on Codelivly. Knowing how a Caesar shift works is enough, and online tools or a short script can help you test key guesses.