Comptia Security+ Cryptography Exam 1

Question 1 of 50

1. Question

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A message is authentic and digitally signed if sent with:

A message digest/hash encrypted with the sender’s private key
A message digest/hash encrypted with the sender’s public key
A message digest/hash encrypted with the receiver’s private key
A message digest/hash encrypted with the receiver’s private key

Question 2 of 50

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Heart of Data Encryption Standard (DES), is the

Cipher
Rounds
Encryption
DES function

Question 3 of 50

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Digital Signatures are:

Proof of authenticity of the sender
Proof of authenticity of the receiver
Proof of authenticity of the verifier
Proof of authenticity of Alice

Question 4 of 50

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In symmetric-key cryptography, the key used by sender and receiver is

Shared
Different
Two keys are used
None

Question 5 of 50

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In symmetric key cryptography, key(s) used for encryption and decryption is/are

Same
Different
Private
Public

Question 6 of 50

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Keys used in cryptography are:

Secret key
Private key
Public key
All of them
None of them

Question 7 of 50

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Cryptography can provide:

All of them
Entity authentication
Nonrepudiation of messages
Confidentiality

Question 8 of 50

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Advanced Encryption Standard (AES), has three different configurations with respect to number of rounds and ________

Key Size
Datasize
Round Size
Encryption Size

Question 9 of 50

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Cryptography algorithms (ciphers) are divided into:

Two groups.
Four groups.
One single group
None

Question 10 of 50

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In cryptography, original message, before being transformed, is called

Simple text
Plain text
Empty text
Filled text

Question 11 of 50

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A hash function guarantees integrity of a message. It guarantees that message has not been _______________.

Replaced
Over view
Changed
Left

Question 12 of 50

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Message digest is referred to:

RSA
Digital signature
Hash function
Digital signature with hash function

Question 13 of 50

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SHA means:

Secret Hash Algorithm
Secure Hash Algorithm
Sneaky Hash Algorithm
Super Hash Algorithm

Question 14 of 50

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Number of submissions for SHA-3 algorithm:

15
64
128
45

Question 15 of 50

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SHA-1 has a message digest of :

160 bits
512 bits
628 bits
820 bits

Question 16 of 50

16. Question

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To check integrity of a message or document, receiver creates the :

Cipher text
Hash
Hyper Text
Finger Print

Question 17 of 50

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A digital signature needs a:

Private key
Shared key
Public key
Both A and C
None of them

Question 18 of 50

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Symmetric encryption:

Used to conceal the contents of block or stream of data of any size, including messages, files, encryption keys, and passwords
Used to conceal small blocks of data, such as encryption keys and hash function values, which are used in digital signatures
Used to protect blocks of data, such as messages, from alteration
These are schemes based on the use of cryptographic algorithms designed to authenticate the identity of entities

Question 19 of 50

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Asymmetric encryption:

Used to conceal the contents of block or stream of data of any size, including messages, files, encryption keys, and passwords
Used to conceal small blocks of data, such as encryption keys and hash function values, which are used in digital signatures
Used to protect blocks of data, such as messages, from alteration
These are schemes based on the use of cryptographic algorithms designed to authenticate the identity of entities

Question 20 of 50

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Authentication protocol:

Used to conceal the contents of block or stream of data of any size, including messages, files, encryption keys, and passwords
Used to conceal small blocks of data, such as encryption keys and hash function values, which are used in digital signatures
Used to protect blocks of data, such as messages, from alteration
These are schemes based on the use of cryptographic algorithms designed to authenticate the identity of entities

Question 21 of 50

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What is Computer Security

Protection afforded to an automated information system in order to attain the applicable objectives of preserving the integrity, availability, and confidentiality of information system resources
Preserving authorized restrictions on information access and disclosure, including means for protecting personal privacy and proprietary information.
Guarding against improper information modification or destruction, including ensuring information nonrepudiation and authenticity.
Ensuring timely and reliable access to and use of information.

Question 22 of 50

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What is Confidentiality?

Protection afforded to an automated information system in order to attain the applicable objectives of preserving the integrity, availability, and confidentiality of information system resources
Preserving authorized restrictions on information access and disclosure, including means for protecting personal privacy and proprietary information.
Guarding against improper information modification or destruction, including ensuring information nonrepudiation and authenticity.
Ensuring timely and reliable access to and use of information.

Question 23 of 50

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What is Integrity?

Protection afforded to an automated information system in order to attain the applicable objectives of preserving the integrity, availability, and confidentiality of information system resources
Preserving authorized restrictions on information access and disclosure, including means for protecting personal privacy and proprietary information.
Guarding against improper information modification or destruction, including ensuring information nonrepudiation and authenticity.
Ensuring timely and reliable access to and use of information.

Question 24 of 50

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What is Availability?

Protection afforded to an automated information system in order to attain the applicable objectives of preserving the integrity, availability, and confidentiality of information system resources
Preserving authorized restrictions on information access and disclosure, including means for protecting personal privacy and proprietary information.
Guarding against improper information modification or destruction, including ensuring information nonrepudiation and authenticity.
Ensuring timely and reliable access to and use of information.

Question 25 of 50

25. Question

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How many rounds of processing uses DES?

14
15
16
17

Question 26 of 50

26. Question

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What is the encryption key size of DES

8-bytes
56-bit
34-bit
64-bit

Question 27 of 50

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Diffusion

Means that the relationship between the encryption key and the ciphertext must be as complex as possible
Means that each plaintext bit must affect as many ciphertext bits as possible
Means that each bit of the key must affect as many bits as possible
Means that each row of a substitution table is indexed by the two outermost bits of a six-bit block and each column by the remaining inner 4 bit

Question 28 of 50

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AES is

3 times faster than 3DES
4 times faster than 3DES
5 times faster than 3DES
6 times faster than 3DES

Question 29 of 50

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AES is

Symmetric key encryption
Assymetric key encryption

Question 30 of 50

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AES input data is

128 bit
192 bit
256 bit
512 bit

Question 31 of 50

31. Question

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Operation in AES is based on

Substitution
Permutation
Substitution-permutation

Question 32 of 50

32. Question

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In AES, 192 bit key has:

10 rounds
12 rounds
14 rounds

Question 33 of 50

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What is the difference between stream cipher and one-time pad?

Stream cipher uses truly random number stream
One-time pad uses truly random number stream
One-time pad uses genuine random number stream

Question 34 of 50

34. Question

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What is the difference between stream cipher and one-time pad?

One-time pad uses truly random number stream
Stream cipher uses pseudo random number stream
Both A & B

Question 35 of 50

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Asymmetric Keys:

Two related keys, a public key and a private key, that are used to perform complementary operations, such as encryption and decryption or signature verification
A digital document issued and digitally signed by the private key of a Certification Authority that binds the name of a subscriber to a public key. The certificate indicates that the subscriber identified in the certificate has sole control and access to the corresponding private key.
A cryptographic algorithm that uses two related keys, a public key and a private key. The two keys have the property that deriving the private key from the public key is computationally infeasible.
A set of policies, processes, server platforms, software and workstation used for the purpose of administering certificates and public-private key pairs, including the ability to issue, maintain, and revoke public key certificates.

Question 36 of 50

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Public Key Certificate:

Two related keys, a public key and a private key, that are used to perform complementary operations, such as encryption and decryption or signature verification
A digital document issued and digitally signed by the private key of a Certification Authority that binds the name of a subscriber to a public key. The certificate indicates that the subscriber identified in the certificate has sole control and access to the corresponding private key.
A cryptographic algorithm that uses two related keys, a public key and a private key. The two keys have the property that deriving the private key from the public key is computationally infeasible.
A set of policies, processes, server platforms, software and workstation used for the purpose of administering certificates and public-private key pairs, including the ability to issue, maintain, and revoke public key certificates.

Question 37 of 50

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Public Keys Cryptography Algorithm:

Two related keys, a public key and a private key, that are used to perform complementary operations, such as encryption and decryption or signature verification
A digital document issued and digitally signed by the private key of a Certification Authority that binds the name of a subscriber to a public key. The certificate indicates that the subscriber identified in the certificate has sole control and access to the corresponding private key.
A cryptographic algorithm that uses two related keys, a public key and a private key. The two keys have the property that deriving the private key from the public key is computationally infeasible.
A set of policies, processes, server platforms, software and workstation used for the purpose of administering certificates and public-private key pairs, including the ability to issue, maintain, and revoke public key certificates.

Question 38 of 50

38. Question

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Public Key Infrastructure:

Two related keys, a public key and a private key, that are used to perform complementary operations, such as encryption and decryption or signature verification
A digital document issued and digitally signed by the private key of a Certification Authority that binds the name of a subscriber to a public key. The certificate indicates that the subscriber identified in the certificate has sole control and access to the corresponding private key.
A cryptographic algorithm that uses two related keys, a public key and a private key. The two keys have the property that deriving the private key from the public key is computationally infeasible.
A set of policies, processes, server platforms, software and workstation used for the purpose of administering certificates and public-private key pairs, including the ability to issue, maintain, and revoke public key certificates.

Question 39 of 50

39. Question

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Public-key encryption has ___ingredients:

5
6
7
4

Question 40 of 50

40. Question

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RSA was presented in

1969
1977
1979
1991

Question 41 of 50

41. Question

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Public key cryptosystem provides authentication:

True
False

Question 42 of 50

42. Question

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Public key cryptosystem provides confidentiality:

True
False

Question 43 of 50

43. Question

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Public key cryptosystem provides availability:

True
False

Question 44 of 50

44. Question

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In RSA:

P – prime, q – any number
P – any number, q – prime
P,q – prime
P,q – any numbers

Question 45 of 50

45. Question

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The first published public-key algorithm

Diffie-Hellman
RSA
Elgamal
AES

Question 46 of 50

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The purpose of Diffie-Hellman algorithm:

To enable two users to securely exchange a key that can then be used for asymmetric encryption of message
To enable two users to securely exchange a key that can then be used for symmetric encryption of message
To enable two users to insecurely exchange a key that can then be used for asymmetric encryption of message
To enable two users to insecurely exchange a key that can then be used for symmetric encryption of message

Question 47 of 50

47. Question

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Difficulty of Diffie-Hellman algorithm depends on:

Prime factorization
Computing discrete logarithm
Euler’s totient function
Euclid’s formula

Question 48 of 50

48. Question

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Message privacy means that sender and receiver expect:

Integrity
Confidentiality
Authentication
Nonrepudiation

Question 49 of 50

49. Question

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An encryption algorithm transforms plaintext into

Cipher text
Plain text
Empty text
Filled text

Question 50 of 50

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Ciphers of today are called round ciphers because they involve

Single Round
Double Rounds
Multiple Round

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