Joe Is Exchanging Encrypted Email with Another Party

question 622

Multiple Choice

Joe is exchanging encrypted email with another party. Joe encrypts the initial email with a key. When Joe receives a response, he is unable to decrypt the response with the same key he used initially. Which of the following would explain the situation?

• A) An ephemeral key was used for one of the messages
• B) A stream cipher was used for the initial email; a block cipher was used for the reply
• C) Out-of-band key exchange has taken place
• D) Asymmetric encryption is being used

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