Encrypt or decrypt a Running Key Vigenere Cipher

This can be used to create (encrypt) and solve (decrypt) a Running Key Vigenere Cipher. A Vigenere cipher uses a table of alphabetic Caesar shifts for one to twenty-six. The key is made to have an equal length to the text by adding the first letters of the text to the key. Each letter and corresponding key value determine the grid location to choose the obfuscated letter from.

The Running Key Cipher Wikipedia entry provides more information on the methods used: https://en.wikipedia.org/wiki/Running_key_cipher

Usage

running_key(x, key, decrypt = FALSE, keep_punctuation = FALSE)

Arguments

x

A vector to be encoded or decoded.

key

A character vector of length one to use as a key

decrypt

(Default: FALSE) The default FALSE will encrypt while using TRUE will decrypt a given value of x.

keep_punctuation

(Default: FALSE) The default FALSE will ignore case and punctuation and return a lowercase result. TRUE will match the input's case and punctuation.

Value

A character vector of length equal to x that has been transformed

Examples

key <- "thisismysupersecurekey"
(e1 <- running_key("abcde", key))
#> [1] "tikvm"
running_key(e1, key, decrypt = TRUE)
#> [1] "abcde"

(e2 <- running_key("cipheR is a great R package!", key))
#> [1] "vpxzmjuqsagirlvrutokkc"
running_key(e2, key, decrypt = TRUE)
#> [1] "cipherisagreatrpackage"

(e3 <- running_key("Isn't this fun?", key, keep_punctuation = TRUE))
#> [1] "Bzv'l bzuq xoc?"
running_key(e3, key, decrypt = TRUE, keep_punctuation = TRUE)
#> [1] "Isn't this fun?"