Cryptography important info Flashcards by Sam Morgan

Certificate revocation list (CRL)

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What needs to be installed on end users’ computers to allow them to trust applications that have been digitally signed by the developer?

Sender’s public key
Sender’s private key
Administrator’s public key
Administrator’s private key

Sender’s public key

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Which type of certificate must be certified by an authority to verify it with other participants?

Public
Root
Private
Domain

Public

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What is an attribute of the Rivest Cipher 4 (RC4) algorithm?

It encrypts whole blocks of data at a time.
It is an asymmetric cipher.
Its keys are longer than the encrypted message.
It requires a unique nonce.

It requires a unique nonce.

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Which mode generates the key stream with a nonce and incrementing value?

Electronic codebook (ECB)
Cipher block chaining (CBC)
Output feedback (OFB)
Counter (CTR)

Counter (CTR)

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Which mode is a stream algorithm that concatenates an incrementing value with a nonce?

Electronic codebook (ECB)
Cipher block chaining (CBC)
Output feedback (OFB)
Counter (CTR)

Counter (CTR)

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Which key would an administrator use to encrypt data so only the CEO can decrypt it?

Administrator’s private key
Administrator’s public key
CEO’s private key
CEO’s public key

CEO’s public key

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What is the result of a hash function?

Digest
Signature
Ciphertext
Plaintext

Digest

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What is used to efficiently encrypt large files?

Hash function
XML function
Asymmetric encryption
Symmetric encryption

Symmetric encryption

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An administrator needs to encrypt the following word with the Atbash cipher:

security

Which ciphertext is correct?

hvxfirgb
hemfirjc
hexfirgc
hyxfigrb

hvxfirgb

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Which cryptographic algorithm has a 128-bit hash size?

Secure Hash Algorithm 1 (SHA-1)
Message Digest Algorithm 5 (MD5)
Triple Data Encryption Standard (3DES)
Advanced Encryption Standard (AES)

Message Digest Algorithm 5 (MD5)

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Which characteristic makes a hashing function suitable for use in signature schemes?

Varying operational modes
Use of bit-by-bit encryption
Use of unique key values
Collision resistance

Collision resistance

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Which attribute of a hashing function makes a birthday attack possible?

Man-in-the-middle detection
Partial-message collision
Brute-force protection
Plaintext

Partial-message collision

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Which hash algorithm produces a 160-bit output value?

SHA-1
MD5
SHA-2
Diffie-Hellman

SHA-1

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What does cipher block chaining (CBC) use with the key to encrypt subsequent blocks of plaintext?

Counter
Nonce
Previous generated ciphertext
Previous plaintext

Previous generated ciphertext

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Which mode produces the same ciphertext from two identical plaintext blocks?

Electronic codebook (ECB)

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Which encryption mode is least secure?

Cipher block chaining (CBC)		
Cipher feedback (CFB)		
Electronic codebook (ECB)		
Output feedback (OFB)

Electronic codebook (ECB)

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What is the mathematical formula used for symmetric decryption?

P = E (K,C)		
C = E (K,P)		
E = C (K,P)		
K = C (P,E)

P = E (K,C)

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Which algorithm relies on factoring the product of large prime numbers?

Elliptical curve
ElGamal
Rivest–Shamir–Adleman
Diffie–Hellman

Rivest–Shamir–Adleman

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Which encryption technology is a serial combination of hashing, data compression, symmetric-key cryptography, and public key infrastructure (PKI) and can be used for encrypting texts, emails, files, and directories or for full disk encryption?

Pretty Good Privacy (PGP)
Wired Equivalent Privacy (WEP)
Diffie–Hellman (DH)
Rivest–Shamir–Adleman (RSA)

Pretty Good Privacy (PGP)

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Which concept stipulates that algorithms should be openly shared and scrutinized, but keys must be absolutely secured?

Communication Theory of Secrecy Systems
Kerckhoffs’s principle
Feistel function
Mathematical Theory of Communication

Kerckhoffs’s principle

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Which encryption process minimizes known plaintext attacks against Advanced Encryption Standard (AES)? Randomizing the initialization vector Using a hashing algorithm Increasing the block size Decreasing the block size

Randomizing the initialization vector

What prevents a rainbow table attack during the encryption process? Increasing key size Decreasing key size Stretching Salting

Salting

Which factor increases the required number of attempts in a brute-force attack?

Larger key size

What is a vulnerability of the Data Encryption Standard (DES)?

Key length is too short.

Which block size does the Advanced Encryption Standard (AES) use? 64 128 192 256

128

Which block algorithm includes a provision for the decryption key kept in a key escrow? Blowfish Serpent Skipjack Twofish

Skipjack

What is the result of A|B and B|C? B|A C|B A|C C|A

A|C

How is X mod N if N = PQ represented in number theory? (((( A- B)( Q − 1 mod Q))mod Q) Q+ B )mod P ( P mod X, Q mod X) (((( A+ B)( Q − 1 mod P))mod P) Q+ B )mod P ( X mod P, X mod Q)

( X mod P, X mod Q)

What is the outcome when using the binary AND function on 11011 and 10100? 01110 10000 11110 21111

10000

Which mode does the Fortuna algorithm use to generate random numbers? Electronic codebook (ECB) Cipher block chaining (CBC) Output feedback (OFB) Counter (CTR)

Counter (CTR)

What is a potential weakness of a pseudo-random number generator (PRNG)? Unknown internal state Different state used each time Random internal state Same state used more than once

Same state used more than once

Which key combination is used to decrypt and verify a digital signature? Recipient’s public key to decrypt and sender’s private key to verify the signature Recipient’s private key to decrypt and sender’s public key to verify the signature Sender’s public key to decrypt and recipient’s private key to verify the signature Sender’s private key to decrypt and recipient’s public key to verify the signature

Recipient’s private key to decrypt and sender’s public key to verify the signature

Which key is used to sign a message or a message digest? Recipient’s private key Recipient’s public key Sender’s private key Sender’s public key

Sender’s private key

Which key does the certificate authority (CA) use to digitally sign keys that it issues? Recipient’s private key Recipient’s public key Server’s private key Server’s public key

Server’s private key

What does an end user need to verify a Rivest–Shamir –Adleman (RSA) digitally signed message? Recipient’s private key Recipient’s public key Sender’s private key Sender’s public key

Sender’s public key

What is used when creating a digital signature, using public key infrastructure (PKI)? The digest as the key after hashing the message The private key of the person receiving the message The private key of the person creating the message The symmetric key known between the sender and receiver

The private key of the person creating the message

Which feature in Wired Equivalent Privacy (WEP) provides integrity control when sending packets over a wireless network? Nonce Network password Cyclic redundancy check Secret key

Cyclic redundancy check

Which feature of Wi-Fi Protected Access (WPA) increases the difficulty of attack? Temporal Key Integrity Protocol (TKIP) Pre-shared key (PSK) Extensible Authentication Protocol (EAP) Internet Key Exchange (IKE)

Temporal Key Integrity Protocol (TKIP)

Which two concerns does the use of Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (CCMP) address? Choose 2 answers. ``` Confidentiality Nonrepudiation Availability Accountability Integrity ```

Confidentiality | Integrity

Which extension designates a file containing a password-protected private key? .cer .pem .p7b .p12

.p12

Which part of the public key infrastructure (PKI) defines how a credential is used? ``` Certificate authority (CA) Certificate policy (CP) Public Key Cryptography Standards (PKCS) Registration authority (RA) ```

Certificate policy (CP)

Which part of the public key infrastructure (PKI) is used to ensure that the format for a credential can be used by anyone on the internet? ``` Certificate authority (CA) Certificate policy (CP) Public Key Cryptography Standards (PKCS) Registration authority (RA) ```

Public Key Cryptography Standards (PKCS)

Which solution is used in a Layer 2 Tunneling Protocol (L2TP) virtual private network (VPN) to secure data in transmission? Cipher block chaining (CBC) Hypertext Transfer Protocol Secure (HTTPS) Microsoft Point-to-Point Encryption (MPPE) Internet Protocol Security (IPsec)

Internet Protocol Security (IPsec)

Which network-based virtual private network (VPN) prevents unauthorized logins by preventing packet retransmission? Point to Point Tunneling Protocol (PPTP) IP security (IPsec) Layer 2 Tunneling Protocol (L2PT) Transport Layer Security (TLS)

IP security (IPsec)

Which port does Secure Socket Tunneling Protocol (SSTP) use? 389 443 1701 1723

443

What is a common problem with using pre-shared keys (PSKs)? Key collision Secure key exchange Key generation Secure key escrow

Secure key exchange

What is a concern with storing long-term secrets on media or memory? Integrity Randomness Modularization Assertions

Integrity

Which cipher uses a series of ciphers based on a keyword? Affine Atbash Caesar Vigenère

Vigenère

Which substitution cipher system reverses the sequence of the alphabet? Atbash Caesar ROT13 Affine

Atbash

Which type of cipher converts a letter to a number, passes it through a mathematical function, and then converts it back to a letter? Atbash Caesar ROT13 Affine

Affine

Which technique solves polyalphabetic substitution ciphers by deducing the key length? Kasiski’s method Frequency analysis Exhaustive search Rainbow tables

Kasiski’s method

Which cryptanalysis technique examines ciphertext for recurring letter combinations? Rainbow table Dictionary attack Frequency analysis Exhaustive search

Frequency analysis

Which cryptanalysis method involves a person being tricked into encrypting a set of known messages? Ciphertext-only attack Chosen plaintext attack Frequency analysis Kasiski examination

Chosen plaintext attack

Which technique does related-key cryptanalysis use to decipher a message? Ciphertext messages are created from plaintext that is chosen by the analyst to determine how the algorithm works. Encrypted messages are gathered, and the analyst looks for patterns to figure out which algorithm is being used. Messages are encrypted using different secrets, and the analyst compares the messages to figure out how the algorithm works. Plaintext messages and corresponding ciphertext are gathered to help the analyst learn about the algorithm.

Messages are encrypted using different secrets, and the analyst compares the messages to figure out how the algorithm works.

Which type of cryptography is being used when the author uses secret inks? Cryptanalysis Steganography Digital encryption One-time pad

Steganography

What is the hidden message in a steganographic communication? Bit Carrier Channel Payload

Payload