1. Engineering
2. Computer Science
3. 1a for this question use the following definitions let m...

# Question: 1a for this question use the following definitions let m...

###### Question details

1A.

For this question, use the following definitions.

• Let m be a message
• Let Ka+ be the public key for Alice, and Ka+(m) be the function expression which indicates the message, m, is encrypted using Alice's public key
• Let Ka- be the private key for Alice, and Ka-(m) be the function expression which indicates the message, m, is encrypted using Alice's private key
• Let Kb+ be the public key for Bob, and Kb+(m) be the function expression which indicates the message, m, is encrypted using Bob's public key
• Let Kb- be the private key for Bob, and Kb-(m) be the function expression which indicates the message, m, is encrypted using Bob's private key
• Let Ka+() be the inverse function of Ka-(), so Ka+(Ka-(m))=Ka-(Ka+(m))=m
• Let Kb+() be the inverse function of Kb-(), so Kb+(Kb-(m))=Kb-(Kb+(m))=m
• Let H() be a hash function

QUESTION: If Alice wants to send a message that only Bob can read, what message does she send?

 Ka-(m)
 Ka+(Kb-(m))
 Kb+(Ka+(m), H(m))
 Kb-(m)
 Ka+(m)
 Kb+(m)
 Ka+(Kb+(m))

1B.

For this question, use the following definitions.

1. Let m be a message
2. Let Ka+ be the public key for Alice, and Ka+(m) be the function expression which indicates the message, m, is encrypted using Alice's public key
3. Let Ka- be the private key for Alice, and Ka-(m) be the function expression which indicates the message, m, is encrypted using Alice's private key
4. Let Kb+ be the public key for Bob, and Kb+(m) be the function expression which indicates the message, m, is encrypted using Bob's public key
5. Let Kb- be the private key for Bob, and Kb-(m) be the function expression which indicates the message, m, is encrypted using Bob's private key
6. Let Ka+() be the inverse function of Ka-(), so Ka+(Ka-(m))=Ka-(Ka+(m))=m
7. Let Kb+() be the inverse function of Kb-(), so Kb+(Kb-(m))=Kb-(Kb+(m))=m
8. Let H() be a hash function

QUESTION: If Alice wants to send a message that only Bob can read, AND that Bob can know that the message must have come from Alice, what message does she send?

 Kb-(m, H(m))
 Kb-(Ka+(m))
 Ka-(Ka+(m))
 Kb+(Kb-(m))
 Kb-(Kb+(m))
 Ka+(Ka-(m))
 Kb+(Ka-(m))
 Ka+(Kb-(m))
 Ka-(Kb+(m))
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