Encrpyts && Decrypts

BY SEPEHR TAHERI && DAN DAIGLE


CAESER
purpose
	encrypt/decrypt P using Caesar cipher with key K
preconditions
	P: string of A..Z
	K in 0..25


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SUBSTITUTION
purpose
	encrypt/decrypt P using substitution cipher with key K
preconditions
	P: string of A..Z
	K: permutation of A..Z

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VERNAM
purpose
	encrypt/decrypt P using Vernam cipher with key K
	if len(P) > len(K) then repeat the key as needed
preconditions
	P: string of A..Z
	K: non-empty list of int in 0..25

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BOOK
purpose
	encrypt/decrypt P using book cipher with key K
	if len(P) > len(K) then repeat the key as needed
preconditions
	P: string of A..Z
	K: non-empty string of A..Z


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COLUMNAR TRANSPOSITION
purpose
	encrypt/decrypt P using columnar transposition cipher with key K
preconditions
	P: string of A..Z
	K > 0

			

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RSA 
purpose
	encrypt/decrypt P using RSA encryption with key K e,n
preconditions
	P: list of positive integers
	e,n selected according to the RSA requirements


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TOOL: DIGRAM EVALUATOR
purpose
	return a dictionary D where
		D.keys contains all of the digrams in S
		D[d] is the number of occurrences of digram d in S
preconditions
	S is a string of A..Z