36. Hill cipher can be broken by
a.None of these
b.Statistical attack
c.Known
plaintext-ciphertext attack
d.ciphertext-only attack
33. In RSA algorithm, if the prime numbers P= 41, and
Q=13, then ɸ[n]=…………….. (Note: just write the number in the box; don’t write
any additional information, e.g., if your answer 16, write 16 in the box, don’t
write anything else, don’t write =16, don’t add extra space, etc...)
480
31. The sender uses ………………………… , then ………………………… for
encryption to satisfy Authenticity and Confidentiality
a.(1) receiver public key, (2) sender private key
b.None of these
c.(1) sender public key, (2) sender private key
d.(1) sender private key, (2) receiver public key
e.(1) receiver
private key, (2) receiver public key
26. Asymmetric encryption can be used for both
confidentiality and authentication
a.FALSE
b.TRUE
30. Is 2 a multiplicative inverse of 16 in mod 31(T)
17. In RSA algorithm, if the prime numbers P= 29, and Q=13,
the receiver selects 61 as his or her public key, then the receiver private key
based on the given information will be ……………….. Hint: you need to calculate the
multiplicative inverse of 61 based on the given parameters. (Note: just write
the number in the box; don’t write any additional information, e.g., if your
answer 16, write 16 in the box don’t write anything else, don’t write =16,
don’t add extra space, etc…)
Answer:377
بس لما يكون p=17
Answer:
P=23 answer:
15. The decision has come down from upper management that
access requirements should be slightly reduced Which access model allows users
some flexibility for information -sharing purposes ?(DAC)
a.
(1) receiver public key, (2) sender private key
b.(1)
receiver private key, (2) receiver public key
(ANSWER)
c.None of these
d.(1) sender public key, (2) sender private key
e.(1) sender private key, (2) receiver public key
12. The sender uses ………………………… , then ………………………… for
encryption to satisfy Authenticity and Confidentiality
7. Diffie-Hellman Key Exchange. Let q=23. Use α = 7 as a
primitive root of q, Xa=6 and Xb=4. Note that for the correctness of the given
options, α must be a primitive root of q otherwise none of the options might be
correct. Generate the secret (session) key for two parties Alice and Bob and
select the correct answer
a.2
b.None of these
c.8
d.3(answer)
4-In an authentication using symmetric keys, if n people need to
communicate, we need n * (n-1)/2 Keys: TRUE
5-A hash function accepts a variable-length block of data M as input and
produces a variable-size hash value: false
6-If we use the Hill cipher with m=2 to encrypt plaintext “COMP” by
using the key matrix , then the obtained cipher text is. (Note: use modulo 26):
EQOR
7-Diffie-Hellman Key Exchange. Let q=23. Use α = 7 as a primitive root
of q, Xa=6 and Xb=4. Note that for the correctness of the given options, α must
be a primitive root of q otherwise none of the options might be correct.
Generate the secret (session) key for two parties Alice and Bob and select the
correct answer: 3
8-The process of converting the ciphertext to plaintext is known as
ciphering or encryption.:FALSE
9-The main concern with DES has been its vulnerability to brute-force
attack because of its relatively short key length:True
11- Recently, some flaws have been discovered in the
authentication protocol, decide which of the following flaws were discovered?:
a. It relies on RSA keys that were insufficiently long
b. None of these
c. It allows for an eavesdropper
to impersonate a client to another server
d. It allows for an eavesdropper to impersonate a server to another
client
e. No problems have been discovered with the protocol
12- The sender uses ………………………… , then ………………………… for
encryption to satisfy Authenticity and Confidentiality: b
a.
(1) receiver public key, (2) sender private key
b. (1) receiver
private key, (2) receiver public key
c.None of these
d.(1) sender public key, (2) sender private key
e.(1) sender private key, (2) receiver public key
14- The SHA-1, MD4 and MD5 all are producing 128 bit
as a hash value: false
15- The decision has come down from upper management
that access requirements should be slightly reduced Which access model allows
users some flexibility for information -sharing purposes ?:DAC
17- Asymmetric encryption can be used for
confidentiality but not for authentication.:FALSE
18- RSA is a block cipher encryption algorithm: False
23-asymmetric encryption can be used for confidetiatily but not for
authentication: False
25- In RSA algorithm, if the prime numbers P= 23, and
Q=13, then N=…………….. (Note: just write the number in the box; don’t write any
additional information, e.g., if your answer 16, write 16 in the box don’t
write anything else, don’t write =16, don’t add extra space, etc…):377
29- Asymmetric encryption can be used for both
confidentiality and authentication: TRUE
31- Recently, some flaws have been discovered in the
authentication protocol, decide which of the following flaws were discovered?
a. It relies on RSA keys that were insufficiently long
b. None of these
c. It allows for an eavesdropper to impersonate a server to another
client
d. It allows for an eavesdropper
to impersonate a client to another server
e. No problems have been discovered with the protocol
32- One of the requirements of public key
cryptography, it should be computationally easy to encrypt the message and
infeasible to compute the private key based on the knowledge of public key:TRUE
33- The decision has come down from upper management
that access requirements should be slightly reduced Which access model allows
users some flexibility for information -sharing purposes ?: DAC
34- Is 2 a multiplicative inverse of 16 in mod 31:TRUE
36- There are no practical cryptanalytic attacks on
3DES.: TRUE
37- If we use extended Vigenere cipher (26 English
letters and 10 decimal digits) to encrypt “CS2 8” using key word “CSENG”. Then,
we obtain ---------------------- as a ciphertext. Note that take blank into
your account z=25, blank=26, 1=27…... Hint: Use modular arithmetic.: ek28
38- Hill cipher can be broken by: Known plaintext-ciphertext
attack
43- The …………………………… is used by the …………………………… to
decrypt the message in PKI, if the goal of encryption was to satisfy integrity:
Public key, receiver
44- DES uses a 64-bit block and a 56-bit key.:TRUE
45- The number 14 is co-prime to 17: TRUE
46- When using symmetric encryption it is very
important to keep the algorithm secret.: FALSE
47- Diffie-Hellman Key Exchange. Let q=17. Use α = 7
as a primitive root of q, Xa=3 and Xb=2. Note that for the correctness of the
given options, α must be a primitive root of q otherwise none of the options
might be correct. Generate the secret (session) key for two parties Alice and
Bob and select the correct answer: 9
a.6
b.15
c.9
d. None of these
e.4
49-A HASh function accepts a variable _length block of data Mas input
and produces avariable size hash value: False
51- RSA method provides a one-time session key for two
parties : TRUE
54- RSA is a block cipher encryption algorithm: FALSE
55- Needham-Schroeder Protocol is a third-party key
distribution protocol: TRUE
59- an object, person, or other entity that represents
a constant danger to an asset: THREAT
60- in RSA algorithm, if the prime numbers P= 31, and
Q=13, the receiver selects 67 as his or her public key, then the receiver
private key based on the given information will be ……………….. Hint: you need to
calculate the multiplicative inverse of 67 based on the given parameters:
62- ………………Displays all connections and listening (open) ports in your system: netstat –a
64- DES uses a key generator to generate sixteen 56
round keys: FALSE
69- In RSA algorithm, if the prime numbers P= 17, and
Q=13, the receiver selects 59 as his or her public key, then the receiver
private key based on the given information will be ……………….. Hint: you need to
calculate the multiplicative inverse of 59 based on the given parameters.
(Note: just write the number in the box; don’t write any additional
information, e.g., if your answer 16, write 16 in the box don’t write anything
else, don’t write =16, don’t add extra space, etc...):179
70- In Vigenère Cipher, you have given the following
cipher text
"KCCPKBGUFDPHQTYHJVAJUWETMCMSPKQDYHJVDAHCTRL SVSKCGC"
Based on the given cipher text, the key length will be:
a. 15
b. None of these
c. 5
d. 6
e.3
f.18
71- Message digest function MD5 is used for
a. Digest of a string
b. None of these
c. Digest and signature of a
string
d. Signature of a string
72- The counter mode performs encryption as and the
following sequence of , where and IV is an initial vector: FALSE
75- in computer security,……. Means that computer system assets can be
modified only by authorized parities: Integrity
76- The number 14 is co-prime to 26: FALse
83- Diffie-Hellman Key Exchange. Let q=23. Use α = 7
as a primitive root of q, Xa=5 and Xb=3. Note that for the correctness of the
given options, α must be a primitive root of q otherwise none of the options
might be correct. Generate the secret (session) key for two parties Alice and
Bob and select the correct answer
a.19
b. None of these
c.14
d.15
e.2
86- A hash function guarantees integrity of a message.
It guarantees that message has not been
a. None of these
b. theft
c. Disclosed
d. Modified
e. Replaced
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