MATA02H3 Lecture Notes - Lecture 3: Whvw, Encryption

• School: UTSC
• Department: Mathematics
• Course: MATA02H3
• Professor: Parnesh Grover

Document Summary

Here is how the decryption process works: to recover the original message in the case of. Caesar cipher, replace each of these numbers p by (p 3) (mod 26) i. e. shift back each letter by three letters in the alphabet, with the first three letters sent to the last three letters. Example 3: decrypt the message whvw eoxh mhdqv, which was encrypted using the caesar cipher. Replace each letter with the corresponding element of (mod 26) in the encrypted message. Replace each of these numbers p by (p 3) (mod 26), Then the decryption function is p ! (p + k) (mod 26) p ! (p k) (mod 26) Example 4: decrypt the message lewlyplujl pz h nylha alhjoly that was encrypted using the shift cipher with k = 7. Solution: replace each letter with the corresponding element of (mod 26) in the encrypted message. Replace each of these numbers p by (p 7) (mod 26),