Which one of the following statements BEST describes the operation of
the Digital Signature Algorithm (DSA) (National Institute of Standards
and Technology, NIST FIPS PUB 186, Digital Signature Standard,
A.
A message of < 264 bits is input to the DSA, and the resultant
message digest of 160 bits is fed into the Secure Hash Algorithm
(SHA), which generates the digital signature of the message.
B.
A message of < 264 bits is input to the Secure Hash Algorithm (SHA),
and the resultant message digest of 160 bits is used as the digital
signature of the message.
C.
A message of < 264 bits is input to the Secure Hash Algorithm (SHA),
and the resultant message digest of 160 bits is fed into the DSA,
which generates the digital signature of the message.
D.
A message of < 264 bits is input to the Secure Hash Algorithm (SHA),
and the resultant message digest of 128 bits is fed into the DSA,
which generates the digital signature of the message.
Explanation:
The correct answer describes the proper sequence of operating on the message
and has the correct value of 160 bits for the SHAmessage digest.
At the receiving end, the message is fed into the SHA, and the result is
compared to the received message digest to verify the signature.
*Answer “A message of < 264 bits is input to the DSA, and the resultant
message digest of 160 bits is fed into the Secure Hash Algorithm (SHA), which generates the
digital signature of the message” is incorrect since the order of the DSA and SHA are in reverse
sequence from the correct order of their application.
* Answer “A message of < 264 bits is input to the Secure Hash Algorithm (SHA),
and the resultant message digest of 128 bits is fed into the DSA,
which generates the digital signature of the message.” is incorrect since it has the incorrect value
of 128 bits for the message digest produced by the SHa.
* Answer “A message of < 264 bits is input to the Secure Hash Algorithm (SHA),
and the resultant message digest of 160 bits is used as the digital
signature of the message” is incorrect since the message digest has to be fed into the DSA to
generate the digital signature of
the message.