Substitution and Vigenère Ciphers

Upload to Canvas a PDF scan of your work for problems 1–2. For this assignment, you will probably prefer to type. Any mode of typing is fine, just export to PDF and upload a PDF.

Assignment: due Wednesday, 11:59 pm

0. Add the file vigtools.R to the R directory of your Package. Delete the NAMESPACE file and rebuild (Clean and Install). You should see three new functions in the package documentation, and ROxygen will generate a new NAMESPACE file for you.

1. The following ciphertext was encrypted by a substitution cipher. The plaintext is from a book written in English. Perform a letter-frequency analysis attack to find the plaintext.

   • In words, (not in code) describe: Which letters did you identify using single-letter frequency? Which did you identify using digrams?
   • Include a copy of the decyrpted plaintext.

olkkaljllsldkwejnxdklejtbhegzxbndxzptyktbwypaweglelwbyowyqwodxpptbdzbxnkalkxsjxqehexkalbqxbjdkalqxbuxzqxbyjnwuhegwejqxbyjpaweghegwblrowejywbglkalqxbuxzlyhkldgwklullslbdqaxsbxvhjlpblwkhvljhblpkhxewejnwewglnlekqhkahedsalbldxzdxphwyyhzllvleqalblkalhnslktdzxbpawegljbwqdzbxnsxstywbwghkwkhxehkjxldexkgwhekbwpkhxetekhyhkhdlnrbwpljwejsbxswgwkljrolyhkldkalblwdxezxbkahdwdhawvldwhjhdkawkptyktblhdwrxtkaxqdxphlkhldjlzhelblwyhkoqawkhdgxxjrwjbhgakqbxegblwyteblwyhnsxbkwektehnsxbkwekwejdxxekahdpwswphkohdexklvleyojhdkbhrtkljhewdxphlkortkhdpxeplekbwkljheplbkwhehedkhktkhxedwejwnxegplbkwheylwjlbdahsgbxtsdqaxawvlwyxsdhjljwpplddkxkalnlwedxzptyktbwysbxjtpkhxekaldllyhkldxslbwklheqlyyjlvlyxsljelkqxbudwejsxqlbztyhedkhktkhxedxvlbkhnlptyktbwyheexvwkhxehdkbwedywkljwejjhzztdljjllsbxxkljptyktbwypaweglklejdkxrlgheqhkakaxdlqaxdlqxbuhdnxdkpxeplsktwywejhevhdhrylwejhknxvldkabxtgakxkaxdlqaxdlqxbuhdnxdkpxepblklwejvhdhrylhewvlbopbtjlzxbntywkhxekalsbxplddrlghedqhkakalxbhdkdqaxglelbwklhjlwdwejuexqyljglnxvldkxbldlwbpalbdqaxlfsyxblblvhdllfswejwejvwyhjwklhjlwdnxvldxekxklwpalbdwejljtpwkxbdqaxswddkaxdlhjlwdxekxxkalbdkaleswddldxekxsxstywbhilbdqaxdhnsyhzohjlwdwejsbwpkhkhxelbdqaxwssyokaxdlhjlwdwyyxzkahdxzpxtbdlkbwedshbldkabxtgaelkqxbudwejdkbtpktbldxzptyktbwysbxjtpkhxeptyktbwypaweglhdnxdklejtbhegqalehkslelkbwkldkaldkbtpktblxzxtbhnwghewkhxezbwnlqxbudxzuexqyljglwejjhdptddhxekalslbplskhxexzlvlbojwoblwyhkokahdbwblyohzlvlbawssledkabxtgagbwddbxxkdsxyhkhpwynxrhyhiwkhxekaxtgagbwddbxxkdnxrhyhiwkhxepwerlwnwehzldkwkhxexzjllslbptyktbwykbwedzxbnwkhxe

2. The following key vector

   keyVec <- c(2,7,20,24)

   was used to create the following ciphertext using a Vigenère cipher. Find the plaintext.

   voyywabmtvzrjlksqaygpabcryytkvoqryiznlgguhqcnselqdhqqjcmnvaguazpqtnfgbhgxllqkasmhccpiphgc