单项选择题
With PGP， which of the following entity signs a users’s public key？（）
A. The sender of the message.
B. The receipient of the message.
C. The sender’s administrator who provides the sender with the PGP program.
D. A third party that belongs to what’s often known as "web of trust"， that can verify the relationship between the user and the key.
E. The vendor of the PGP program.
相关考题
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单项选择题
WhenconfiguringamultipointGRE（mGRE）tunnelinterface，whichoneofthefollowingisNOTavalidconfigurationoption：（）
A. tunnel source
B. tunnel destination
C. tunnel key
D. ip address
E. tunnelvrf -
多项选择题
WhichofthefollowingstatementsthatdescribeDiffieHellmanKeyexchangearecorrect？（）
A. A DH key exchange is an algorithm that utilizes asymmetric cryptographic keys.
B. The DH key exchange is used to establish a shared secret over an insecure medium during an IPSec phase 1 exchange.
C. The DH exchange is susceptible to man-in-the-middle attacks.
D. The DH exchange is used to authenticate the peer device duringan IPSec phase 1 exchange.
E.A DH exchange provides Perfect Forward Secrecy （PFS）. -
多项选择题
SelectthetwocorrectstatementsfromthelistbelowthatdescribeDESand3DES：（）
A. 3DES is muchmore secure than DES.
B. Both DES and 3DES are stream ciphers.
C. DES uses 64 bitkeys， although the effective key lengthis only 56bits.
D. The decryption operation for both DES and 3DES is the same as the encryption operation.
E. DES can only be used for encryption， whereas 3DES can also be used for authentication.
