Encrypt the message "this is an exercise" using an additive cipher with a key of 20. Ignore the space between words. Decrypt the message to obtain the original plaintext.
Added by Philip C.
Step 1
An additive cipher is a type of monoalphabetic substitution cipher where each letter in the plaintext is shifted a certain number of places down or up the alphabet. In this case, the key is 20, meaning each letter will be shifted 20 places down the alphabet. Show more…
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