Symmetric Encryption and Publickey Crytography (ch20, 21) Flashcards

1
Q

Symmetric encryption is also referred to as secret-key or single-key encryption.

A

True

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2
Q

The ciphertext-only attack is the easiest to defend against.

A

True

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3
Q

A brute-force approach involves trying every possible key until an intelligible translation of the ciphertext into plaintext is obtained.

A

True

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4
Q

AES uses a Feistel structure.

A

False

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5
Q

Each block of 64 plaintext bits is encoded independently using the same key? is a description of the CBC mode of operation.

A

False

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6
Q

Timing attacks are only applicable to RSA.

A

False

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7
Q

Using PKCS (public-key cryptography standard), when RSA encrypts the same message twice, different ciphertexts will be produced.

A

True

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8
Q

The Diffie-Hellman algorithm depends for its effectiveness on the difficulty of computing discrete logarithms.

A

True

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9
Q

A key exchange protocol is vulnerable to a man-in-the-middle attack if it does not authenticate the participants.

A

True

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10
Q

Just like RSA can be used for signature as well as encryption, Digital Signature Standard can also be used for encryption.

A

False

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11
Q

In general, public key based encryption is much slower than symmetric key based encryption.

A

True

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12
Q

________ is the original message or data that is fed into the encryption process as input.

A. Plaintext

B. Encryption algorithm

C. Decryption algorithm

D. Ciphertext

A

A

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13
Q

Which of the following would allow an attack that to know the (plaintext of) current message must be the same as one previously transmitted because their ciphtertexts are the same?

A. CBC

B. ECB

C. CFB

D. OFB

A

B

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14
Q

________ is a term that refers to the means of delivering a key to two parties that wish to exchange data without allowing others to see the key.

A. Session key

B. Subkey

C. Key distribution technique

D. Ciphertext key

A

C

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15
Q

Which of the following feature can only be provided by public-key cryptography?

A. Confidentiality protection

B. Integrity protection

C. Non-repudiation

D. None of the above

A

C

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16
Q

Cryptographic systems are generically classified by _______.

A. the type of operations used for transforming plaintext to ciphertext

B. the number of keys used

C. the way in which the plaintext is processed

D. all of the above

A

D

17
Q

________ attacks have several approaches, all equivalent in effort to factoring the product of two primes.

A. Mathematical

B. Brute-force

C. Chosen ciphertext

D. Timing

A

A

18
Q

________ are analogous to a burglar guessing a safe combination by observing how long it takes to turn the dial from number to number.

A. Digital standards

B. Mathematical attacks

C. Ciphers

D. Timing attacks

A

D

19
Q

_________ was the first published public-key algorithm.

A. NIST

B. Diffie-Hellman

C. RC4

D. RSA

A

B

20
Q

The principal attraction of ________ compared to RSA is that it appears to offer equal security for a far smaller bit size, thereby reducing processing overhead.

A. ECC

B. MD5

C. Diffie-Hellman

D. none of the above

A

A

21
Q

To decrypt using DES, same algorithm is used, but with per-round keys used in the reversed order.

A

True

22
Q

With Triple DES the effective key length can be 56, 112, and 168

A

True

23
Q

Each round of DES contains both substitution and permutation operations.

A

True

24
Q

The logics behind the S-boxes are well-known and verified

A

False

25
Q

To decrypt using AES, just run the same algorithm in the same order of operations.

A

False

26
Q

Each operation or stage in AES is reversible.

A

True

27
Q

AES can support key length of 128, 192, 256

A

True

28
Q

AES is much more efficient than Triple DES.

A

True

29
Q

CBC is more secure than ECB.

A

True

30
Q

We can have both confidentiality and integrity protection with CBC by using just one key.

A

False

31
Q

RSA is a block cipher in which the plaintext and ciphertext are integers between 0 and n - 1 for some n.

A

True

32
Q

If someone invents a very efficient method to factor large integers, then RSA becomes insecure.

A

True