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Problem 6. You are trying to break a Vigenre cipher using frequency analysis of the ciphertext LCYFQPNGCYTNKVVEAKKYNKTFSWDYRNAEERQQOCCMHSPFSHAEKRZIUVLEIWPYYAZINWAEVYDFIZCYDF IDZEJVLOAIRLOODDCDSRXCEOKYCALRECHHZTFPNTIWATJKFPMVJQLGVRSEODRRTCRCJJAEUQPNUJGE BRTIZNCPYQRZVLOLPRGCPCRLPIJRQDUDVBEOYRTPTYVAZRIVAEKVPAZMGRPPTYVKPSJREPFIFKEHVG JLNVNGEHKYCNOIICNTCPCYCIPNEEUDCDSRXCTFKYCJMRKASTYVNWAEVGDFIZCYDCPGQNFKGESKYCPN VDWSONVTPRKYCPNVDWNAEJCYDRCYCGVESXBVIMQCYFQPNDVQDAXVQEOFECZFPFSCPCRLPSREBWOFBY ETYVPPSLCRTNXTGAHVIRPXKJGQTYZQLLCFUDTYVKEOUVBFCVKFPKVPRSEVECXYTRLPQLZNEHVZPALR ECDSFKFPYTRLXAJHSPRRUCLSWIGPNUCW (a) Use
Problem 6. You are trying to break a Vigenre cipher using frequency analysis of the ciphertext LCYFQPNGCYTNKVVEAKKYNKTFSWDYRNAEERQQOCCMHSPFSHAEKRZIUVLEIWPYYAZINWAEVYDFIZCYDF IDZEJVLOAIRLOODDCDSRXCEOKYCALRECHHZTFPNTIWATJKFPMVJQLGVRSEODRRTCRCJJAEUQPNUJGE BRTIZNCPYQRZVLOLPRGCPCRLPIJRQDUDVBEOYRTPTYVAZRIVAEKVPAZMGRPPTYVKPSJREPFIFKEHVG JLNVNGEHKYCNOIICNTCPCYCIPNEEUDCDSRXCTFKYCJMRKASTYVNWAEVGDFIZCYDCPGQNFKGESKYCPN VDWSONVTPRKYCPNVDWNAEJCYDRCYCGVESXBVIMQCYFQPNDVQDAXVQEOFECZFPFSCPCRLPSREBWOFBY ETYVPPSLCRTNXTGAHVIRPXKJGQTYZQLLCFUDTYVKEOUVBFCVKFPKVPRSEVECXYTRLPQLZNEHVZPALR ECDSFKFPYTRLXAJHSPRRUCLSWIGPNUCW (a) Use the method from 2.3.1 of the textbook to find the number of matching characters in the first line of the ciphertext and its displacement by 2 characters. Do this using "only paper and pencil" and show your work. (b) Find the number of matching characters in the entire given ciphertext and its displacement by j characters for j=1,2,,13. You may (and probably want to) use the function MatchCount () from Problem 5 to collect the data. (c) Use the result of (b) to guess the length of the key used to encrypt the above ciphertext. (d) Use the method from $2.3.2 of the textbook (the "first method for finding the key") to guess the first letter of the key
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