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NEW QUESTION 38
Which one of the following is an authentication method that sends the username and password in cleartext?
- A. SPAP
- B. CHAP
- C. PAP
- D. Kerberos
Answer: C
Explanation:
PAP
https://en.wikipedia.org/wiki/Password_Authentication_Protocol
Password Authentication Protocol (PAP) is a password-based authentication protocol used by Point to Point Protocol (PPP) to validate users. Almost all network operating system remote servers support PAP. PAP is specified in RFC 1334.
PAP is considered a weak authentication scheme (weak schemes are simple and have lighter computational overhead but are much more vulnerable to attack; while weak schemes may have limited application in some constrained environments, they are avoided in general). Among PAP's deficiencies is the fact that it transmits unencrypted passwords (i.e. in plain-text) over the network. PAP is therefore used only as a last resort when the remote server does not support a stronger scheme such as CHAP or EAP.
Incorrect answers:
SPAP - Shiva Password Authentication Protocol, PAP with encryption for the usernames/passwords that are transmitted.
CHAP - calculates a hash, shares the hash with the client system, the hash is periodically validated to ensure nothing has changed.
Kerberos - computer-network authentication protocol that works on the basis of tickets to allow nodes communicating over a non-secure network to prove their identity to one another in a secure manner. Its designers aimed it primarily at a client-server model and it provides mutual authentication-both the user and the server verify each other's identity. Kerberos protocol messages are protected against eavesdropping and replay attacks.
Kerberos builds on symmetric key cryptography and requires a trusted third party, and optionally may use public-key cryptography during certain phases of authentication.
NEW QUESTION 39
The most common way steganography is accomplished is via which one of the following?
- A. Isb
- B. rsb
- C. asb
- D. msb
Answer: A
Explanation:
lbs
https://en.wikipedia.org/wiki/Bit_numbering#:~:text=In%20computing%2C%20the%20least%20significant,number%20is%20even%20or%20odd.
The least significant bit (LSB) is the bit position in a binary integer giving the units value, that is, determining whether the number is even or odd. The LSB is sometimes referred to as the low-order bit or right-most bit, due to the convention in positional notation of writing less significant digits further to the right. It is analogous to the least significant digit of a decimal integer, which is the digit in the ones (right-most) position.
NEW QUESTION 40
Which service in a PKI will vouch for the identity of an individual or company?
- A. CA
- B. CR
- C. CBC
- D. KDC
Answer: A
Explanation:
CA
https://en.wikipedia.org/wiki/Certificate_authority
A certificate authority or certification authority (CA) is an entity that issues digital certificates. A digital certificate certifies the ownership of a public key by the named subject of the certificate. This allows others (relying parties) to rely upon signatures or on assertions made about the private key that corresponds to the certified public key. A CA acts as a trusted third party-trusted both by the subject (owner) of the certificate and by the party relying upon the certificate. The format of these certificates is specified by the X.509 or EMV standard.
NEW QUESTION 41
Which of the following is the standard for digital certificates?
- A. X.509
- B. RFC 2298
- C. 509 is a standard defining the format of public key certificates. X.509 certificates are used in many Internet protocols, including TLS/SSL, which is the basis for HTTPS, the secure protocol for browsing the web. They are also used in offline applications, like electronic signatures. An X.509 certificate contains a public key and an identity (a hostname, or an organization, or an individual), and is either signed by a certificate authority or self-signed. When a certificate is signed by a trusted certificate authority, or validated by other means, someone holding that certificate can rely on the public key it contains to establish secure communications with another party, or validate documents digitally signed by the corresponding private key.
- D. CRL
- E. CA
- F. 509
https://en.wikipedia.org/wiki/X.509
Answer: A
NEW QUESTION 42
In relationship to hashing, the term _____refers to random bits that are used as one of the inputs to the hash. Essentially the ______ is intermixed with the message that is to be hashed
- A. Stream
- B. IV
- C. Salt
- D. Vector
Answer: C
Explanation:
Salt
https://en.wikipedia.org/wiki/Salt_(cryptography)
A salt is random data that is used as an additional input to a one-way function that hashes data, a password or passphrase. Salts are used to safeguard passwords in storage. Historically a password was stored in plaintext on a system, but over time additional safeguards were developed to protect a user's password against being read from the system. A salt is one of those methods.
Incorrect answers:
Vector - Wrong!
IV - an initialization vector or starting variable (SV) is a fixed-size input to a cryptographic primitive that is typically required to be random or pseudorandom. Randomization is crucial for encryption schemes to achieve semantic security, a property whereby repeated usage of the scheme under the same key does not allow an attacker to infer relationships between segments of the encrypted message. For block ciphers, the use of an IV is described by the modes of operation. Randomization is also required for other primitives, such as universal hash functions and message authentication codes based thereon.
Stream - A stream cipher is a symmetric key cipher where plaintext digits are combined with a pseudorandom cipher digit stream (keystream). In a stream cipher, each plaintext digit is encrypted one at a time with the corresponding digit of the keystream, to give a digit of the ciphertext stream. Since encryption of each digit is dependent on the current state of the cipher, it is also known as state cipher. In practice, a digit is typically a bit and the combining operation is an exclusive-or (XOR).
NEW QUESTION 43
In 2007, this wireless security algorithm was rendered useless by capturing packets and discovering the passkey in a matter of seconds. This security flaw led to a network invasion of TJ Maxx and data theft through a technique known as wardriving.
Which Algorithm is this referring to?
- A. Wi-Fi Protected Access (WPA)
- B. Wi-Fi Protected Access 2 (WPA2)
- C. Wired Equivalent Privacy (WEP)
- D. Temporal Key Integrity Protocol (TKIP)
Answer: C
Explanation:
Wired Equivalent Privacy (WEP)
https://en.wikipedia.org/wiki/Wired_Equivalent_Privacy#Weak_security
In 2007, Erik Tews, Andrei Pychkine, and Ralf-Philipp Weinmann were able to extend Klein's 2005 attack and optimize it for usage against WEP. With the new attack it is possible to recover a 104-bit WEP key with probability 50% using only 40,000 captured packets. For 60,000 available data packets, the success probability is about 80% and for 85,000 data packets about 95%. Using active techniques like deauth and ARP re-injection, 40,000 packets can be captured in less than one minute under good conditions. The actual computation takes about 3 seconds and 3 MB of main memory on a Pentium-M 1.7 GHz and can additionally be optimized for devices with slower CPUs. The same attack can be used for 40-bit keys with an even higher success probability.
NEW QUESTION 44
What is a TGS?
- A. The server that escrows keys
- B. A protocol for key exchange
- C. The server that grants Kerberos tickets
- D. A protocol for encryption
Answer: C
Explanation:
The server that grants Kerberos tickets
https://en.wikipedia.org/wiki/Kerberos_(protocol)
The client authenticates itself to the Authentication Server (AS) which forwards the username to a key distribution center (KDC). The KDC issues a ticket-granting ticket (TGT), which is time stamped and encrypts it using the ticket-granting service's (TGS) secret key and returns the encrypted result to the user's workstation. This is done infrequently, typically at user logon; the TGT expires at some point although it may be transparently renewed by the user's session manager while they are logged in.
NEW QUESTION 45
Ferris has been assigned the task of selecting security for his company's wireless network. It is important that he pick the strongest form of wireless security. Which one of the following is the strongest wireless security?
- A. WPA
- B. WPA2
- C. TKIP
- D. WEP
Answer: B
Explanation:
WPA2
https://en.wikipedia.org/wiki/Wi-Fi_Protected_Access
WPA (sometimes referred to as the draft IEEE 802.11i standard) became available in 2003. The Wi-Fi Alliance intended it as an intermediate measure in anticipation of the availability of the more secure and complex WPA2, which became available in 2004 and is a common shorthand for the full IEEE 802.11i (or IEEE 802.11i-2004) standard.
NEW QUESTION 46
Message hidden in unrelated text. Sender and receiver have pre-arranged to use a pattern to remove certain letters from the message which leaves only the true message behind.
- A. Null Ciphers
- B. Caesar Cipher
- C. Playfair Cipher
- D. Vigenere Cipher
Answer: A
Explanation:
Null Ciphers
https://en.wikipedia.org/wiki/Null_cipher
A null cipher, also known as concealment cipher, is an ancient form of encryption where the plaintext is mixed with a large amount of non-cipher material. Today it is regarded as a simple form of steganography, which can be used to hide ciphertext.
Incorrect answers:
Caesar Cipher - Monoalphabetic cipher where letters are shifted one or more letters in either direction. The method is named after Julius Caesar, who used it in his private correspondence.
Vigenere - method of encrypting alphabetic text by using a series of interwoven Caesar ciphers, based on the letters of a keyword. It employs a form of polyalphabetic substitution.
Playfair Cipher - manual symmetric encryption technique and was the first literal digram substitution cipher. The scheme was invented in 1854 by Charles Wheatstone, but bears the name of Lord Playfair for promoting its use.
NEW QUESTION 47
The greatest weakness with symmetric algorithms is _____.
- A. The problem of generating keys
- B. The problem of key exchange
- C. They are less secure than asymmetric
- D. They are slower than asymmetric
Answer: B
Explanation:
The problem of key exchange
https://en.wikipedia.org/wiki/Symmetric-key_algorithm
Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both encryption of plaintext and decryption of ciphertext. The keys may be identical or there may be a simple transformation to go between the two keys. The keys, in practice, represent a shared secret between two or more parties that can be used to maintain a private information link. This requirement that both parties have access to the secret key is one of the main drawbacks of symmetric key encryption, in comparison to public-key encryption (also known as asymmetric key encryption).
NEW QUESTION 48
The reverse process from encoding - converting the encoded message back into its plaintext format.
- A. Whitening
- B. Substitution
- C. Encoding
- D. Decoding
Answer: D
Explanation:
Decoding
Decoding - reverse process from encoding,converting the encoded message back into its plaintext format.
NEW QUESTION 49
Frank is trying to break into an encrypted file... He is attempting all the possible keys that could be used for this algorithm. Attempting to crack encryption by simply trying as many randomly generated keys as possible is referred to as what?
- A. Brute force
- B. Rainbow table
- C. Frequency analysis
- D. Kasiski
Answer: A
Explanation:
Brute force
https://en.wikipedia.org/wiki/Brute-force_attack
Brute-force attack consists of an attacker submitting many passwords or passphrases with the hope of eventually guessing correctly. The attacker systematically checks all possible passwords and passphrases until the correct one is found. Alternatively, the attacker can attempt to guess the key which is typically created from the password using a key derivation function. This is known as an exhaustive key search.
Incorrect answers:
Kasiski - Kasiski examination (also referred to as Kasiski's test or Kasiski's method) is a method of attacking polyalphabetic substitution ciphers, such as the Vigenere cipher. It was first published by Friedrich Kasiski in 1863, but seems to have been independently discovered by Charles Babbage as early as 1846.
Rainbow table - is a precomputed table for caching the output of cryptographic hash functions, usually for cracking password hashes. Tables are usually used in recovering a key derivation function (or credit card numbers, etc.) up to a certain length consisting of a limited set of characters. It is a practical example of a space-time tradeoff, using less computer processing time and more storage than a brute-force attack which calculates a hash on every attempt, but more processing time and less storage than a simple key derivation function with one entry per hash. Use of a key derivation that employs a salt makes this attack infeasible.
Frequency analysis - (also known as counting letters) is the study of the frequency of letters or groups of letters in a ciphertext. The method is used as an aid to breaking classical ciphers.
NEW QUESTION 50
Which of the following is an asymmetric cipher?
- A. RC4
- B. DES
- C. RSA
- D. AES
Answer: C
Explanation:
RSA
https://en.wikipedia.org/wiki/RSA_(cryptosystem)
RSA (Rivest-Shamir-Adleman) is a public-key cryptosystem that is widely used for secure data transmission. It is also one of the oldest. The acronym RSA comes from the surnames of Ron Rivest, Adi Shamir, and Leonard Adleman, who publicly described the algorithm in 1977. An equivalent system was developed secretly, in 1973 at GCHQ (the British signals intelligence agency), by the English mathematician Clifford Cocks. That system was declassified in 1997.
In a public-key cryptosystem, the encryption key is public and distinct from the decryption key, which is kept secret (private). An RSA user creates and publishes a public key based on two large prime numbers, along with an auxiliary value. The prime numbers are kept secret. Messages can be encrypted by anyone, via the public key, but can only be decoded by someone who knows the prime numbers.
Incorrect answers:
DES - is a symmetric-key algorithm for the encryption of digital data. Although its short key length of 56 bits makes it too insecure for applications, it has been highly influential in the advancement of cryptography.
RC4 - RSA (Rivest-Shamir-Adleman) is one of the first public-key cryptosystems and is widely used for secure data transmission (stream cipher).
AES - is a subset of the Rijndael block cipher developed by two Belgian cryptographers, Vincent Rijmen and Joan Daemen, who submitted a proposal to NIST during the AES selection process. Rijndael is a family of ciphers with different key and block sizes. For AES, NIST selected three members of the Rijndael family, each with a block size of 128 bits, but three different key lengths: 128, 192 and 256 bits.
NEW QUESTION 51
Which of the following is assured by the use of a hash?
- A. Availability
- B. Confidentiality
- C. Integrity
- D. Authentication
Answer: C
Explanation:
Integrity
https://en.wikipedia.org/wiki/Cryptographic_hash_function#Verifying_the_integrity_of_messages_and_files An important application of secure hashes is verification of message integrity. Comparing message digests (hash digests over the message) calculated before, and after, transmission can determine whether any changes have been made to the message or file.
NEW QUESTION 52
With Cipher-block chaining (CBC) what happens?
- A. The message is divided into blocks and each block is encrypted separately. This is the most basic mode for symmetric encryption
- B. The block cipher is turned into a stream cipher
- C. Each block of plaintext is XORed with the previous ciphertext block before being encrypted
- D. The cipher text from the current round is XORed with the plaintext for the next round
Answer: C
Explanation:
Each block of plaintext is XORed with the previous ciphertext block before being encrypted
https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_block_chaining_(CBC) In CBC mode, each block of plaintext is XORed with the previous ciphertext block before being encrypted. This way, each ciphertext block depends on all plaintext blocks processed up to that point. To make each message unique, an initialization vector must be used in the first block.
NEW QUESTION 53
Protocol suite provides a method of setting up a secure channel for protected data exchange between two devices.
- A. OCSP
- B. IPSec
- C. CLR
- D. TLS
Answer: B
Explanation:
IPSec
https://en.wikipedia.org/wiki/IPsec
Internet Protocol Security (IPsec) is a secure network protocol suite that authenticates and encrypts the packets of data to provide secure encrypted communication between two computers over an Internet Protocol network. It is used in virtual private networks (VPNs).
Incorrect answers:
OCSP - Online Certificate Status Protocol (OCSP) is an Internet protocol used for obtaining the revocation status of an X.509 digital certificate.
CRL - is a list of digital certificates that have been revoked by the issuing certificate authority (CA) before their scheduled expiration date and should no longer be trusted.
TLS - Transport Layer Security, and its now-deprecated predecessor, Secure Sockets Layer (SSL), are cryptographic protocols designed to provide communications security over a computer network. Several versions of the protocols find widespread use in applications such as web browsing, email, instant messaging, and voice over IP (VoIP). Websites can use TLS to secure all communications between their servers and web browsers.
NEW QUESTION 54
Basic information theory is the basis for modern symmetric ciphers. Understanding the terminology of information theory is, therefore, important. Changes to one character in the plaintext affect multiple characters in the ciphertext. What is this referred to?
- A. Diffusion
- B. Confusion
- C. Avalanche
- D. Scrambling
Answer: A
Explanation:
Diffusion
https://en.wikipedia.org/wiki/Confusion_and_diffusion
Diffusion means that if we change a single bit of the plaintext, then (statistically) half of the bits in the ciphertext should change, and similarly, if we change one bit of the ciphertext, then approximately one half of the plaintext bits should change. Since a bit can have only two states, when they are all re-evaluated and changed from one seemingly random position to another, half of the bits will have changed state.
The idea of diffusion is to hide the relationship between the ciphertext and the plain text.
This will make it hard for an attacker who tries to find out the plain text and it increases the redundancy of plain text by spreading it across the rows and columns; it is achieved through transposition of algorithm and it is used by block ciphers only Incorrect answers:
Confusion
Confusion means that each binary digit (bit) of the ciphertext should depend on several parts of the key, obscuring the connections between the two.
The property of confusion hides the relationship between the ciphertext and the key.
This property makes it difficult to find the key from the ciphertext and if a single bit in a key is changed, the calculation of the values of most or all of the bits in the ciphertext will be affected.
Confusion increases the ambiguity of ciphertext and it is used by both block and stream ciphers.
Avalanche https://en.wikipedia.org/wiki/Avalanche_effect
An avalanche effect is the desirable property of cryptographic algorithms, typically block ciphers and cryptographic hash functions, wherein if an input is changed slightly (for example, flipping a single bit), the output changes significantly (e.g., half the output bits flip). In the case of high-quality block ciphers, such a small change in either the key or the plaintext should cause a drastic change in the ciphertext.
If a block cipher or cryptographic hash function does not exhibit the avalanche effect to a significant degree, then it has poor randomization, and thus a cryptanalyst can make predictions about the input, being given only the output. This may be sufficient to partially or completely break the algorithm. Thus, the avalanche effect is a desirable condition from the point of view of the designer of the cryptographic algorithm or device.
Constructing a cipher or hash to exhibit a substantial avalanche effect is one of the primary design objectives, and mathematically the construction takes advantage of the butterfly effect. This is why most block ciphers are product ciphers. It is also why hash functions have large data blocks. Both of these features allow small changes to propagate rapidly through iterations of the algorithm, such that every bit of the output should depend on every bit of the input before the algorithm terminates.
NEW QUESTION 55
Which of the following is an asymmetric algorithm that was first publically described in 1977?
- A. Twofish
- B. Elliptic Curve
- C. RSA
- D. DESX
Answer: C
Explanation:
RSA
https://en.wikipedia.org/wiki/RSA_(cryptosystem)
RSA (Rivest-Shamir-Adleman) is a public-key cryptosystem that is widely used for secure data transmission. It is also one of the oldest. The acronym RSA comes from the surnames of Ron Rivest, Adi Shamir, and Leonard Adleman, who publicly described the algorithm in 1977.
Incorrect answers:
Elliptic Curve - Elliptic-curve cryptography (ECC) is an approach to public-key cryptography based on the algebraic structure of elliptic curves over finite fields. ECC allows smaller keys compared to non-EC cryptography (based on plain Galois fields) to provide equivalent security.
Twofish - is a symmetric key block cipher with a block size of 128 bits and key sizes up to 256 bits. It was one of the five finalists of the Advanced Encryption Standard contest, but it was not selected for standardization. Twofish is related to the earlier block cipher Blowfish.
DESX - is a variant on the DES (Data Encryption Standard) symmetric-key block cipher intended to increase the complexity of a brute-force attack using a technique called key whitening.
NEW QUESTION 56
____________cryptography uses one key to encrypt a message and a different key to decrypt it.
- A. Secure
- B. Stream
- C. Asymmetric
- D. Symmetric
Answer: C
Explanation:
Asymmetric
https://en.wikipedia.org/wiki/Public-key_cryptography
Public-key cryptography, or asymmetric cryptography, is a cryptographic system that uses pairs of keys: public keys, which may be disseminated widely, and private keys, which are known only to the owner. The generation of such keys depends on cryptographic algorithms based on mathematical problems to produce one-way functions. Effective security only requires keeping the private key private; the public key can be openly distributed without compromising security.
NEW QUESTION 57
Which algorithm implements an unbalanced Feistel cipher?
- A. 3DES
- B. Blowfish
- C. Skipjack
- D. RSA
Answer: C
Explanation:
Skipjack
https://en.wikipedia.org/wiki/Skipjack_(cipher)
Skipjack uses an 80-bit key to encrypt or decrypt 64-bit data blocks. It is an unbalanced Feistel network with 32 rounds.
NEW QUESTION 58
A cryptographic hash function which uses a Merkle tree-like structure to allow for immense parallel computation of hashes for very long inputs. Authors claim a performance of 28 cycles per byte for MD6-256 on an Intel Core 2 Duo and provable resistance against differential cryptanalysis.
- A. MD5
- B. MD6
- C. TIGER
- D. GOST
Answer: B
Explanation:
MD6
https://en.wikipedia.org/wiki/MD6
The MD6 Message-Digest Algorithm is a cryptographic hash function. It uses a Merkle tree-like structure to allow for immense parallel computation of hashes for very long inputs. Authors claim a performance of 28 cycles per byte for MD6-256 on an Intel Core 2 Duo and provable resistance against differential cryptanalysis.[2] The source code of the reference implementation was released under MIT license.
Speeds in excess of 1 GB/s have been reported to be possible for long messages on 16-core CPU architecture.
In December 2008, Douglas Held of Fortify Software discovered a buffer overflow in the original MD6 hash algorithm's reference implementation. This error was later made public by Ron Rivest on 19 February 2009, with a release of a corrected reference implementation in advance of the Fortify Report.
NEW QUESTION 59
A disk you rotated to encrypt/decrypt. Created by Leon Alberti. Similar technologies were used in the Enigma machine. Considered the forefather of modern encryption.
- A. Cipher Disks
- B. Scytale Cipher
- C. Chi Square
- D. Enigma Machine
Answer: A
Explanation:
Cipher disks
https://en.wikipedia.org/wiki/Cipher_disk
A cipher disk is an enciphering and deciphering tool developed in 1470 by the Italian architect and author Leon Battista Alberti. He constructed a device, (eponymously called the Alberti cipher disk) consisting of two concentric circular plates mounted one on top of the other. The larger plate is called the "stationary" and the smaller one the "moveable" since the smaller one could move on top of the "stationary".
NEW QUESTION 60
Which of the following would be the weakest encryption algorithm?
- A. RSA
- B. DES
- C. EC
- D. AES
Answer: B
Explanation:
DES
https://en.wikipedia.org/wiki/Data_Encryption_Standard
DES is insecure due to the relatively short 56-bit key size. In January 1999, distributed.net and the Electronic Frontier Foundation collaborated to publicly break a DES key in 22 hours and 15 minutes.
Incorrect answers:
AES - has been adopted by the U.S. government and is now used worldwide. It supersedes the Data Encryption Standard (DES),which was published in 1977. The algorithm described by AES is a symmetric-key algorithm, meaning the same key is used for both encrypting and decrypting the data.
RSA - The security of RSA relies on the practical difficulty of factoring the product of two large prime numbers, the "factoring problem". Breaking RSA encryption is known as the RSA problem. Whether it is as difficult as the factoring problem is an open question. There are no published methods to defeat the system if a large enough key is used.
EC - Elliptic-curve cryptography (ECC) is an approach to public-key cryptography based on the algebraic structure of elliptic curves over finite fields. ECC allows smaller keys compared to non-EC cryptography (based on plain Galois fields) to provide equivalent security.
NEW QUESTION 61
Storing private keys with a third party is referred to as what?
- A. Key banking
- B. Key escrow
- C. Key caching
- D. Key storage
Answer: B
Explanation:
Key escrow
https://en.wikipedia.org/wiki/Key_escrow
Key escrow (also known as a "fair" cryptosystem) is an arrangement in which the keys needed to decrypt encrypted data are held in escrow so that, under certain circumstances, an authorized third party may gain access to those keys. These third parties may include businesses, who may want access to employees' secure business-related communications, or governments, who may wish to be able to view the contents of encrypted communications (also known as exceptional access).
NEW QUESTION 62
Which of the following equations is related to EC?
- A. Let m = (p-1)(q-1)
- B. Me%n
- C. P = Cd%n
- D. y^2 = x^3 + Ax + B
Answer: D
Explanation:
y^2 = x^3 + Ax + B
https://en.wikipedia.org/wiki/Elliptic-curve_cryptography
For current cryptographic purposes, an elliptic curve is a plane curve over a finite field (rather than the real numbers) which consists of the points satisfying the equation:
NEW QUESTION 63
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