Intro to Sec - Ch. 14
Imagine that you are an attacker. Which would be most desirable when attempting to compromise encrypted data? A A weak key B The algorithm used by the encryption protocol C Captured traffic D A block cipher
A weak key The easiest way for an attacker to get at encrypted data is if that encrypted data has a weak encryption key. The algorithm isn't of much use to an attacker unless it has been broken, which is a far more difficult process than trying to crack an individual key. Captured traffic, if encrypted, still needs to be decrypted, and a weak key will aid in this process. The block cipher is a type of algorithm.
Which of the following is not a valid cryptographic hash function? A RC4 B SHA-512 C MD5 D RIPEMD
RC4 RC4 is a symmetric encryption algorithm that uses a stream cipher. It is the only listed answer that is not a valid cryptographic hash function.
What is another term for secret key encryption? A PKI B Asymmetrical C Symmetrical D Public key
Symmetrical Symmetric key encryption uses a secret key. The term symmetric key is also referred to as the following: private key, single key, and shared key (and sometimes as session key). PKI and public keys at their core are asymmetrical.
The fundamental difference between symmetric key systems and asymmetric key systems is that symmetric key systems do which of the following? A Use the same key on each end B Use different keys on each end C Use multiple keys for non-repudiation purposes D Use public key cryptography
Use the same key on each end Symmetric key systems use the same key on each end during transport of data. Asymmetric key systems (such as public key cryptography systems) use different keys.
Of the following, which statement correctly describes the difference between a secure cipher and a secure hash? A A hash produces a variable output for any input size; a cipher does not. B A cipher produces the same size output for any input size; a hash does not. C A hash can be reversed; a cipher cannot. D A cipher can be reversed; a hash cannot.
A cipher can be reversed; a hash cannot. Ciphers can be reverse engineered but hashes cannot when attempting to re-create a data file. Hashing is not the same as encryption; hashing is the digital fingerprint, so to speak, of a group of data. Hashes are not reversible.
You are attempting to move data to a USB flash drive. Which of the following enables a rapid and secure connection? A SHA-2 B 3DES C AES-256 D MD5
AES-256 AES-256 enables a quick and secure encrypted connection for use with a USB flash drive. It might even be used with a whole disk encryption technology, such as BitLocker. SHA-2 and MD5 are examples of hashes. 3DES is an example of an encryption algorithm but would not be effective for sending encrypted information in a highly secure manner and quickly to a USB flash drive.
What type of attack sends two different messages using the same hash function, which end up causing a collision? A Birthday attack B Bluesnarfing C Man-in-the-middle attack D Logic bomb
Birthday attack A birthday attack exploits the mathematics behind the birthday problem in probability theory. It deals with two different messages using the same hash function, generating the same message digest. Bluesnarfing deals with Bluetooth devices. The man-in-the-middle attack is when a person or computer intercepts information between a sender and the receiver. A logic bomb is a malicious attack set to go off at a particular time; often it is stored on a zombie computer.
Which of the following is the weakest encryption type? A DES B RSA C AES D SHA
DES DES (Data Encryption Standard) was developed in the 1970s; its 56-bit key has been superseded by 3DES (max 168-bit key) and AES (max 256-bit key). DES is now considered to be insecure for many applications. RSA is definitely stronger than DES even when you compare its asymmetric strength to a relative symmetric strength. SHA is a hashing algorithm.
Which of the following is not a symmetric key algorithm? A RC4 B ECC C 3DES D Rijndael
ECC ECC (elliptic curve cryptography) is an example of public key cryptography that uses an asymmetric key algorithm. All the other answers are symmetric key algorithms.
Which of the following is commonly used to perform an integrity check of data? A Public key B Private key C WEP D Hash
Hash A hash provides integrity checks; for example, MD5 hash algorithms.Answers A and B are incorrect. Public and private keys are the element of a cipher that allows for output of encrypted information.Answer C is incorrect. WEP (Wired Equivalent Privacy) is a deprecated wireless encryption protocol.
Which of the following concepts does the Diffie-Hellman algorithm rely on? A Usernames and passwords B VPN tunneling C Biometrics D Key exchange
Key exchange The Diffie-Hellman algorithm relies on key exchange before data can be sent. Usernames and passwords are considered a type of authentication. VPN tunneling is done to connect a remote client to a network. Biometrics is the science of identifying people by one of their physical attributes.
A hash algorithm has the capability to avoid the same output from two guessed inputs. What is this known as? A Collision resistance B Collision strength C Collision cipher D Collision metric
Collision resistance A hash is collision resistant if it is difficult to guess two inputs that hash to the same output.
Which of the following methods will best verify that a download from the Internet has not been modified since the manufacturer released it? A Compare the final LANMAN hash with the original. B Download the patch file over an AES encrypted VPN connection. C Download the patch file through an SSL connection. D Compare the final MD5 hash with the original.
Compare the final MD5 hash with the original. The purpose of the MD5 hash is to verify the integrity of a download. SHA is another example of a hash that will verify the integrity of downloads. LANMAN hashes are older, deprecated hashes used by Microsoft LAN Manager for passwords. Encrypted AES and SSL connections are great for encrypting the data transfer but do not verify integrity.
What does it mean if a hashing algorithm creates the same hash for two different downloads? A A hash is not encrypted. B A hashing chain has occurred. C A one-way hash has occurred. D A collision has occurred.
A collision has occurred. If a hashing algorithm generates the same hash for two different messages within two different downloads, a collision has occurred and the implementation of the hashing algorithm should be investigated.
Sensitive network traffic needs to be protected from interception. Jason, a security administrator, selects a cipher that will encrypt 128 bits at a time before sending the data across the network. Which of the following has Jason chosen? A Stream cipher B Block cipher C Hashing algorithm D RC4
Block cipher Jason chose a block cipher; for example, the 128-bit version of AES. Don't let the phrase "network stream" fool you; stream ciphers will encrypt each bit in the stream. Hashing algorithms are not used to encrypt network streams of data. RC4 is a stream cipher.
You are tasked with selecting an asymmetric encryption method that allows for the same level of encryption strength, but with a lesser key length than is typically necessary. Which encryption method fulfills your requirement? A RSA B ECC C DHE D Twofish
ECC The ECC (elliptic curve cryptography) method allows for lesser key lengths but at the same level of strength as other asymmetric methods. This reduces the computational power needed. RSA and Diffie-Hellman require more computational power due to the increased key length. DHE especially uses more CPU power because of the ephemeral aspect. (ECDHE would be the solution in that respect.) Twofish is a symmetric algorithm.
Which of the following encryption algorithms is used to encrypt and decrypt data? A SHA-256 B RC5 C MD5 D NTLM
RC5 RC5 (Rivest Cipher version 5) can encrypt and decrypt data. SHA-256 is a type of SHA-256 is a type of SHA-2. It and MD5 are used as hashing algorithms, and NTLM (NT LAN Manager) is used by Microsoft as an authentication protocol and a password hash.
Give two examples of hardware devices that can store keys. (Select the two best answers.) A Smart card B Network adapter C PCI Express card D USB flash drive
Smart card, USB flash drive Smart cards and USB flash drives can be used as devices that carry a token and store keys; this means that they can be used for authentication to systems, often in a multifactor authentication scenario. Network adapters and PCI Express cards are internal to a PC and would not make for good key storage devices.
Question 10 :Which type of encryption technology is used with the BitLocker application? A Symmetric B Asymmetric C Hashing D WPA2
Symmetric BitLocker uses symmetric encryption technology based on AES. Hashing is the process of summarizing a file for integrity purposes. WPA2 is a wireless encryption protocol.
Question 6 :Which of the following might a public key be used to accomplish? A To decrypt the hash of a digital signature B To encrypt web browser traffic C To digitally sign a message D To decrypt wireless messages
To decrypt the hash of a digital signature Public keys can be used to decrypt the hash of a digital signature. Session keys are used to encrypt web browser traffic. Private keys are used to digitally sign a message by encrypting a hash of the message.
Your boss wants you to set up an authentication scheme in which employees will use smart cards to log in to the company network. What kind of key should be used to accomplish this? A Private key B Public key C Cipher key D Shared key
Private key A private key should be used by users when logging in to the network with their smart card. The key should certainly not be public. A key actually determines the function of a cipher. Shared key is another term for symmetric key encryption but does not imply privacy.
Which of the following encryption methods deals with two distinct, large prime numbers and the inability to factor those prime numbers? A SHA-1 B RSA C WPA D Symmetric
RSA The RSA encryption algorithm uses two prime numbers. If used properly they will be large prime numbers that are difficult or impossible to factor. SHA-1 is an example of a Secure Hash Algorithm—albeit a deprecated one. WPA is the Wi-Fi Protected Access protocol, and RSA is an example of an asymmetric method of encryption.
You need to encrypt and send a large amount of data. Which of the following would be the best option? A Symmetric encryption B Hashing algorithm C Asymmetric encryption D PKI
Symmetric encryption Symmetric encryption is the best option for sending large amounts of data. It is superior to asymmetric encryption. PKI is considered an asymmetric encryption type, and hashing algorithms don't play into sending large amounts of data.
Which of the following is used by PGP to encrypt the session key before it is sent? A Asymmetric key distribution system B Asymmetric scheme C Symmetric key distribution system D Symmetric scheme
Symmetric scheme Pretty Good Privacy (PGP) encryption uses a symmetric key scheme for the session key data, and asymmetric RSA for the sending of the session key, plus a combination of hashing and data compression. Key distribution systems are part of an entire encryption scheme, which typically includes a technology such as Kerberos (key distribution center) or quantum cryptography.
Last week, one of the users in your organization encrypted a file with a private key. This week the user left the organization, and unfortunately the systems administrator deleted the user's account. What are the most probable outcomes of this situation? (Select the two best answers.) A The data is not recoverable. B The former user's account can be re-created to access the file. C The file can be decrypted with a PKI. D The data can be decrypted using the recovery agent. E The data can be decrypted using the root user account.
The data is not recoverable, The data can be decrypted using the recovery agent.
What does steganography replace in graphic files? A The least significant bit of each byte B The most significant bit of each byte C The least significant byte of each bit D The most significant byte of each bit
The least significant bit of each byte Steganography replaces the least significant bit of each byte. It would be impossible to replace a byte of each bit, because a byte is larger than a bit; a byte is eight bits.
Why would an attacker use steganography? A To hide information B For data integrity C To encrypt information D For wireless access
To hide information Steganography is the act of writing hidden messages so that only the intended recipients know of the existence of the message. This is a form of security through obscurity. Steganographers are not as concerned with data integrity or encryption because the average person shouldn't even know that a message exists. Although steganography can be accomplished by using compromised wireless networks, it is not used to gain wireless access.
When encrypting credit card data, which would be the most secure algorithm with the least CPU utilization? A AES B 3DES C SHA-512 D MD5
AES AES (Advanced Encryption Standard) is fast and secure, more so than 3DES. SHA-512 (a type of SHA-2) and MD5 are hashing algorithms. Not listed is RSA, which is commonly implemented to secure credit card transactions.
Which of the following combines the keystream with the plaintext message using the bitwise XOR operator to produce the ciphertext? A One-time pad B Obfuscation C PBKDF2 D ECDH
One-time pad A one-time pad is a stream cipher that encrypts plaintext with a secret random key that is the same length as the plaintext. Encryption is accomplished by combining the keystream with the plaintext message using the bitwise XOR operator to produce the ciphertext. Obfuscation means to make something obscure and unclear. PBKDF2 is an example of key-stretching software. Elliptic Curve Diffie-Hellman, or ECDH, uses elliptic curve public/private key pairs to establish the secret key.
The IT director wants you to use a cryptographic algorithm that cannot be decoded by being reversed. Which of the following would be the best option? A Asymmetric B Symmetric C PKI D One-way function
One-way function In cryptography, the one-way function is one option of an algorithm that cannot be reversed, or is difficult to reverse, in an attempt to decode data. An example of this would be a hash such as SHA-2, which creates only a small hashing number from a portion of the file or message. There are ways to crack asymmetric and symmetric encryptions, which enable complete decryption (decoding) of the file.
WEP improperly uses an encryption protocol and therefore is considered to be insecure. What encryption protocol does it use? A AES B RSA C RC6 D RC4
RC4 RC4 has several vulnerabilities when used incorrectly by protocols such as WEP. WEP does not use AES, RSA, or RC6, all of which are secure protocols if used correctly.
You are tasked with ensuring that messages being sent and received between two systems are both encrypted and authenticated. Which of the following protocols accomplishes this? A Diffie-Hellman B BitLocker C RSA D SHA-384
RSA RSA can both encrypt and authenticate messages. Diffie-Hellman encrypts only. BitLocker is a type of whole disk encryption (WDE), which deals with encrypting entire hard drives but is not used to send and receive messages. SHA-384 is a cryptographic hash function used to preserve the integrity of files.
