The following cipher text is the result of encrypting an ordinary English text u

Question

The following cipher text is the result of encrypting an ordinary English text using a Vigenère cipher.

Determine the keyword length, and the keyword, and decrypt the text. Show the details of your work. Add

additional paper sheets if needed and staple with this sheet.

OCWYIKOOONIWUGPMXWKTZDWGTSSAYJZWYEMDLBNQAAAVSUWDVBRFLAUPLOOUBFGQHGCSCMGZLATOEDCSD

EIDPBHTMUOVPIEKIFPIMFNOAMVLPQFXEJSMXMPGKCCAYKWFZPYUAVTELWHRHMWKBBVGTGUVTEFJLODFEF

KVPXSGRSORVGTAJBSAUHZRZALKWUOWHGEDEFNSWMRCIWCPAAAVOGPDNFPKTDBALSISURLNPSJYEATCUCE

ESOHHDARKHWOTIKBROQRDFMZGHGUCEBVGWCDQXGPBGQWLPBDAYLOOQDMUHBDQGMYWEUIK

Explanation / Answer

Based on repetitions in the encrypted text, the most probable key length is 6 characters.

The most probable keys based on frequency analysis of the letters in the cipher is 'holmes'

-- MESSAGE w/Key #1 = 'holmes' ----------------
holmeshadbeenseatedforsomehoursinsilencewithhislongthinbackcurvedover
achemicalvesselinwhichhewasbrewingaparticularlymalodorousproducthisheadw
assunkuponhisbreastandhelookedfrommypointofviewlikeastrangelankbirdwithd
ullgreyplumageandablacktopknotsowatsonsaidhesuddenlyyoudonotproposetoinv
estinsouthafricansecurities

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