2 cissp ® Official Study Guide Eighth Edition

2.
Explain the process Alice would use to decrypt the message Bob sent in question 1.
3.
Explain the process Bob should use to digitally sign a message to Alice.
4.
Explain the process Alice should use to verify the digital signature on the message from 
Bob in question 3.

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Review Questions 
271
Review Questions
1.
In the RSA public key cryptosystem, which one of the following numbers will always be 
largest?
A.
e
B.
n
C.
p
D.
q
2.
Which cryptographic algorithm forms the basis of the El Gamal cryptosystem?
A.
RSA
B.
Diffie-Hellman
C.
3DES
D.
IDEA
3.
If Richard wants to send an encrypted message to Sue using a public key cryptosystem, 
which key does he use to encrypt the message?
A.
Richard’s public key
B.
Richard’s private key
C.
Sue’s public key
D.
Sue’s private key
4.
If a 2,048-bit plaintext message were encrypted with the El Gamal public key cryptosys-
tem, how long would the resulting ciphertext message be?
A.
1,024 bits
B.
2,048 bits
C.
4,096 bits
D.
8,192 bits
5.
Acme Widgets currently uses a 1,024-bit RSA encryption standard companywide. The com-
pany plans to convert from RSA to an elliptic curve cryptosystem. If it wants to maintain 
the same cryptographic strength, what ECC key length should it use?
A.
160 bits
B.
512 bits
C.
1,024 bits
D.
2,048 bits

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