200 Exam Questions for 212-81 Updated Versions With Test Engine
Pass 212-81 Exam with Updated 212-81 Exam Dumps PDF 2022
NEW QUESTION 115
If you XOR 10111000 with 10101010, what is the result?
- A. 0
- B. 00010010
- C. 1
- D. 2
Answer: B
Explanation:
00010010
https://en.wikipedia.org/wiki/XOR_cipher
1 0 1 1 1 0 0 0
1 0 1 0 1 0 1 0
________________
0 0 0 1 0 0 1 0
NEW QUESTION 116
During the process of encryption and decryption, what keys are shared?
- A. User passwords
- B. Private keys
- C. Public keys
- D. Public and private keys
Answer: C
Explanation:
Public keys
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.
In such a system, any person can encrypt a message using the receiver's public key, but that encrypted message can only be decrypted with the receiver's private key.
Alice and Bob have two keys of their own - just to be clear, that's four keys total. Each party has their own public key, which they share with the world, and their own private key which they well, which they keep private, of course but, more than that, which they keep as a closely guarded secret. The magic of public key cryptography is that a message encrypted with the public key can only be decrypted with the private key. Alice will encrypt her message with Bob's public key, and even though Eve knows she used Bob's public key, and even though Eve knows Bob's public key herself, she is unable to decrypt the message. Only Bob, using his secret key, can decrypt the message assuming he's kept it secret, of course.
Alice and Bob do not need to plan anything ahead of time to communicate securely: they generate their public-private key pairs independently, and happily broadcast their public keys to the world at large. Alice can rest assured that only Bob can decrypt the message she sends because she has encrypted it with his public key.
NEW QUESTION 117
The time and effort required to break a security measure.
- A. Work factor
- B. Session Key
- C. Non-repudiation
- D. Payload
Answer: A
Explanation:
Work factor
Work factor - the time and effort required to break a security measure.
Incorrect answers:
Non-repudiation - involves associating actions or changes with a unique individual.
Session Key - is a single-use symmetric key used for encrypting all messages in one communication session. A closely related term is content encryption key (CEK), traffic encryption key (TEK), or multicast key which refers to any key used for encrypting messages, contrary to other uses like encrypting other keys (key encryption key (KEK) or key wrapping key).
Payload - is the part of transmitted data that is the actual intended message. Headers and metadata are sent only to enable payload delivery.
NEW QUESTION 118
How did the ATBASH cipher work?
- A. By shifting each letter a certain number of spaces
- B. By substituting each letter for the letter from the opposite end of the alphabet (i.e. A becomes Z, B becomes Y, etc.)
- C. By Multi alphabet substitution
- D. By rotating text a given number of spaces
Answer: B
Explanation:
By substituting each letter for the letter from the opposite end of the alphabet (i.e. A becomes Z, B becomes Y, etc.)
https://en.wikipedia.org/wiki/Atbash
The Atbash cipher is a particular type of monoalphabetic cipher formed by taking the alphabet (or abjad, syllabary, etc.) and mapping it to its reverse, so that the first letter becomes the last letter, the second letter becomes the second to last letter, and so on.
NEW QUESTION 119
Which of the following techniques is used (other than brute force) to attempt to derive a key?
- A. Hacking
- B. Cryptography
- C. Cryptoanalysis
- D. Password cracking
Answer: C
Explanation:
Cryptoanalysis
https://en.wikipedia.org/wiki/Cryptanalysis
Cryptanalysis is the study of analyzing information systems in order to study the hidden aspects of the systems. Cryptanalysis is used to breach cryptographic security systems and gain access to the contents of encrypted messages, even if the cryptographic key is unknown.
NEW QUESTION 120
A type of frequency analysis used to attack polyalphabetic substitution ciphers. It's used to try to discover patterns and use that information to decrypt the cipher.
- A. Birthday Attack
- B. Kasiski Method
- C. Information Deduction
- D. Integral Cryptanalysis
Answer: B
Explanation:
Kasiski Method
https://en.wikipedia.org/wiki/Kasiski_examination
In cryptanalysis, 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.
Incorrect answers:
Integral Cryptanalysis - uses lots of sets of plaintext that are similar with slight modifications. These are encrypted and then the variations are analyzed to determine if there's anything that can be zeroed in on.
Information Deduction - the attacker gains some Shannon information about plaintexts (or ciphertexts) not previously known.
Birthday Attack - cryptographic attack that exploits the mathematics behind the birthday problem in the probability theory forces collisions within hashing functions.
NEW QUESTION 121
Juanita is attempting to hide some text into a jpeg file. Hiding messages inside another medium is referred to as which one of the following?
- A. Cryptology
- B. Steganography
- C. Cryptography
- D. Steganalysis
Answer: B
Explanation:
Steganography
https://en.wikipedia.org/wiki/Steganography
Steganography is the practice of concealing a file, message, image, or video within another file, message, image, or video. The word steganography comes from Greek steganographia, which combines the words steganos, meaning "covered or concealed", and -graphia meaning "writing".
Incorrect answers:
Cryptography, or cryptology, is the practice and study of techniques for secure communication in the presence of third parties called adversaries.
Steganalysis - is the study of detecting messages hidden using steganography; this is analogous to cryptanalysis applied to cryptography.
NEW QUESTION 122
You are explaining basic mathematics to beginning cryptography students. You are covering the basic math used in RSA. A prime number is defined as
- A. Any number only divisible by odd numbers
- B. Odd numbers with no divisors
- C. Any number only divisible by one and itself
- D. Odd numbers
Answer: A
Explanation:
Any number only divisible by one and itself
https://en.wikipedia.org/wiki/Prime_number
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways of writing it as a product, 1 × 5 or 5 × 1, involve 5 itself. However, 4 is composite because it is a product (2 × 2) in which both numbers are smaller than 4. Primes are central in number theory because of the fundamental theorem of arithmetic: every natural number greater than 1 is either a prime itself or can be factorized as a product of primes that is unique up to their order.
NEW QUESTION 123
The concept that if one bit of data changes, the cipher text will all completely change as well.
- A. Confusion
- B. Avalanche
- C. Substitution
- D. Collision
Answer: B
Explanation:
Avalanche
https://en.wikipedia.org/wiki/Avalanche_effect
In cryptography, the 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. The actual term was first used by Horst Feistel, although the concept dates back to at least Shannon's diffusion.
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.
Substitution - method of encrypting by which units of plaintext are replaced with ciphertext, according to a fixed system; the "units" may be single letters (the most common), pairs of letters, triplets of letters, mixtures of the above, and so forth. The receiver deciphers the text by performing the inverse substitution.
Collision - occurs when a hash function generates the same output for different inputs.
NEW QUESTION 124
What size key does Skipjack use?
- A. 256 bit
- B. 56 bit
- C. 80 bit
- D. 128 bit
Answer: C
NEW QUESTION 125
Which one of the following wireless standards uses the Advanced Encryption Standard (AES) using the Counter Mode-Cipher Block Chaining (CBC)-Message Authentication Code (MAC) Protocol (CCMP)?
- A. WPA2
- B. WEP
- C. WEP2
- D. WPA
Answer: A
Explanation:
WPA2
https://en.wikipedia.org/wiki/Wi-Fi_Protected_Access#WPA2
WPA2 use the Counter Mode-Cipher Block Chaining (CBC)-Message Authentication Code (MAC) Protocol (CCMP).
NEW QUESTION 126
Which component of IPsec performs protocol-level functions that are required to encrypt and decrypt the packets?
- A. IPsec Policy Agent
- B. IPsec driver
- C. Internet Key Exchange (IKE)
- D. Oakley
Answer: C
Explanation:
Internet Key Exchange (IKE)
https://en.wikipedia.org/wiki/Internet_Key_Exchange
Internet Key Exchange (IKE, sometimes IKEv1 or IKEv2, depending on version) is the protocol used to set up a security association (SA) in the IPsec protocol suite. IKE builds upon the Oakley protocol and ISAKMP. IKE uses X.509 certificates for authentication - either pre-shared or distributed using DNS (preferably with DNSSEC) - and a Diffie-Hellman key exchange to set up a shared session secret from which cryptographic keys are derived.
Incorrect answers:
Oakley - the Oakley Key Determination Protocol is a key-agreement protocol that allows authenticated parties to exchange keying material across an insecure connection using the Diffie-Hellman key exchange algorithm. The protocol was proposed by Hilarie K. Orman in 1998, and formed the basis for the more widely used Internet Key Exchange protocol.
IPsec Policy Agent - service provides end-to-end security between clients and servers on TCP/IP networks, manages IPsec policy settings, starts the Internet Key Exchange (IKE), and coordinates IPsec policy settings with the IP security driver.
IPsec driver - wrong!
NEW QUESTION 127
Which of the following is assured by the use of a hash?
- A. Confidentiality
- B. Authentication
- C. Availability
- D. Integrity
Answer: D
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 128
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. Confusion
- B. Scrambling
- C. Diffusion
- D. Avalanche
Answer: C
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 129
Which one of the following is an authentication method that sends the username and password in cleartext?
- A. PAP
- B. Kerberos
- C. SPAP
- D. CHAP
Answer: A
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 130
Which of the following is a protocol for exchanging keys?
- A. RSA
- B. AES
- C. DH
- D. EC
Answer: C
Explanation:
DH
https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange
Diffie-Hellman key exchange is a method of securely exchanging cryptographic keys over a public channel and was one of the first public-key protocols as conceived by Ralph Merkle and named after Whitfield Diffie and Martin Hellman. DH is one of the earliest practical examples of public key exchange implemented within the field of cryptography. Published in 1976 by Diffie and Hellman, this is the earliest publicly known work that proposed the idea of a private key and a corresponding public key.
Incorrect answers:
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.
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.
AES - also known by its original name Rijndael, is a specification for the encryption of electronic data established by the U.S. National Institute of Standards and Technology (NIST) in 2001. AES is a subset of the Rijndael block cipher developed by two Belgian cryptographers, Vincent Rijmen and Joan Daemen, who submitted a proposal[5] 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 131
Which of the following areas is considered a strength of symmetric key cryptography when compared with asymmetric algorithms?
- A. Key distribution
- B. Speed
- C. Scalability
- D. Security
Answer: B
Explanation:
Speed
Symmetric key systems are considerably faster than asymmetric key systems but have issues with proper key distribution, controlling keys as more users need to communicate, and cannot provide non-repudiation or authenticity.
NEW QUESTION 132
A real time protocol for verifying certificates (and a newer method than CRL).
- A. Online Certificate Status Protocol (OCSP)
- B. Public Key Infrastructure (PKI)
- C. Registration Authority (RA)
- D. Server-based Certificate Validation Protocol (SCVP)
Answer: A
Explanation:
Online Certificate Status Protocol (OCSP)
https://en.wikipedia.org/wiki/Online_Certificate_Status_Protocol
The Online Certificate Status Protocol (OCSP) is an Internet protocol used for obtaining the revocation status of an X.509 digital certificate. It is described in RFC 6960 and is on the Internet standards track. It was created as an alternative to certificate revocation lists (CRL), specifically addressing certain problems associated with using CRLs in a public key infrastructure (PKI).
Incorrect answers:
Public Key Infrastructure (PKI) - set of roles, policies, hardware, software and procedures needed to create, manage, distribute, use, store and revoke digital certificates and manage public-key encryption. The purpose of a PKI is to facilitate the secure electronic transfer of information for a range of network activities such as e-commerce, internet banking and confidential email. It is required for activities where simple passwords are an inadequate authentication method and more rigorous proof is required to confirm the identity of the parties involved in the communication and to validate the information being transferred.
Registration Authority (RA) - component of PKI that validates the identity of an entity requesting a digital certificate.
Server-based Certificate Validation Protocol (SCVP) - Internet protocol for determining the path between an X.509 digital certificate and a trusted root (Delegated Path Discovery) and the validation of that path (Delegated Path Validation) according to a particular validation policy.
NEW QUESTION 133
Used to take the burden off of a CA by handling verification prior to certificates being issued. Acts as a proxy between user and CA.
Receives request, authenticates it and forwards it to the CA.
- A. PKI (Public Key Infrastructure)
- B. RA (Registration Authority)
- C. TTP (Trusted Third Party)
- D. CP (Certificate Policy)
Answer: B
Explanation:
RA (Registration Authority)
https://en.wikipedia.org/wiki/Registration_authority
Registration authorities exist for many standards organizations, such as ANNA (Association of National Numbering Agencies for ISIN), the Object Management Group, W3C, IEEE and others. In general, registration authorities all perform a similar function, in promoting the use of a particular standard through facilitating its use. This may be by applying the standard, where appropriate, or by verifying that a particular application satisfies the standard's tenants. Maintenance agencies, in contrast, may change an element in a standard based on set rules - such as the creation or change of a currency code when a currency is created or revalued (i.e. TRL to TRY for Turkish lira). The Object Management Group has an additional concept of certified provider, which is deemed an entity permitted to perform some functions on behalf of the registration authority, under specific processes and procedures documented within the standard for such a role.
Incorrect answers:
TTP (Trusted Third Party) - is an entity which facilitates interactions between two parties who both trust the third party; the Third Party reviews all critical transaction communications between the parties, based on the ease of creating fraudulent digital content. In TTP models, the relying parties use this trust to secure their own interactions. TTPs are common in any number of commercial transactions and in cryptographic digital transactions as well as cryptographic protocols, for example, a certificate authority (CA) would issue a digital identity certificate to one of the two parties in the next example. The CA then becomes the Trusted-Third-Party to that certificates issuance. Likewise transactions that need a third party recordation would also need a third-party repository service of some kind or another.
CP (Certificate Policy) - is a document which aims to state what are the different entities of a public key infrastructure (PKI), their roles and their duties. This document is published in the PKI perimeter.
When in use with X.509 certificates, a specific field can be set to include a link to the associated certificate policy. Thus, during an exchange, any relying party has an access to the assurance level associated with the certificate, and can decide on the level of trust to put in the certificate.
PKI (Public Key Infrastructure) - is a set of roles, policies, hardware, software and procedures needed to create, manage, distribute, use, store and revoke digital certificates and manage public-key encryption. The purpose of a PKI is to facilitate the secure electronic transfer of information for a range of network activities such as e-commerce, internet banking and confidential email. It is required for activities where simple passwords are an inadequate authentication method and more rigorous proof is required to confirm the identity of the parties involved in the communication and to validate the information being transferred.
NEW QUESTION 134
What is the basis for the difficulty in breaking RSA?
- A. Factoring numbers
- B. The birthday paradox
- C. Hashing
- D. Equations that describe an elliptic curve
Answer: A
Explanation:
Factoring numbers
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.
NEW QUESTION 135
What is the name of the attack where the attacker obtains the ciphertexts corresponding to a set of plaintexts of his own choosing?
- A. Differential cryptanalysis
- B. Chosen plaintext
- C. Known-plaintext attack
- D. Kasiski examination
Answer: B
Explanation:
Chosen plaintext
https://en.wikipedia.org/wiki/Chosen-plaintext_attack
A chosen-plaintext attack (CPA) is an attack model for cryptanalysis which presumes that the attacker can obtain the ciphertexts for arbitrary plaintexts. The goal of the attack is to gain information that reduces the security of the encryption scheme.
Incorrect answers:
Differential cryptanalysis - is a general form of cryptanalysis applicable primarily to block ciphers, but also to stream ciphers and cryptographic hash functions. In the broadest sense, it is the study of how differences in information input can affect the resultant difference at the output. In the case of a block cipher, it refers to a set of techniques for tracing differences through the network of transformation, discovering where the cipher exhibits non-random behavior, and exploiting such properties to recover the secret key (cryptography key).
Known-plaintext attack - (KPA) is an attack model for cryptanalysis where the attacker has access to both the plaintext (called a crib), and its encrypted version (ciphertext). These can be used to reveal further secret information such as secret keys and code books.
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. In polyalphabetic substitution ciphers where the substitution alphabets are chosen by the use of a keyword, the Kasiski examination allows a cryptanalyst to deduce the length of the keyword. Once the length of the keyword is discovered, the cryptanalyst lines up the ciphertext in n columns, where n is the length of the keyword. Then each column can be treated as the ciphertext of a monoalphabetic substitution cipher. As such, each column can be attacked with frequency analysis.
NEW QUESTION 136
The art and science of writing hidden messages so that no one suspects the existence of the message, a type of security through obscurity. Message can be hidden in picture or audio file for example. Uses least significant bits in a file to store data.
- A. Key Schedule
- B. Steganography
- C. Avalanche effect
- D. Cryptosystem
Answer: B
Explanation:
Steganography
https://en.wikipedia.org/wiki/Steganography
Steganography is the practice of concealing a file, message, image, or video within another file, message, image, or video.
The first recorded use of the term was in 1499 by Johannes Trithemius in his Steganographia, a treatise on cryptography and steganography, disguised as a book on magic. Generally, the hidden messages appear to be (or to be part of) something else: images, articles, shopping lists, or some other cover text. For example, the hidden message may be in invisible ink between the visible lines of a private letter. Some implementations of steganography that lack a shared secret are forms of security through obscurity, and key-dependent steganographic schemes adhere to Kerckhoffs's principle.
Incorrect answers:
Avalanche effect - 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.
Cryptosystem - a suite of cryptographic algorithms needed to implement a particular security service, most commonly for achieving confidentiality (encryption) Key Schedule - an algorithm for the key that calculates the subkeys for each round that the encryption goes through.
NEW QUESTION 137
Which of the following is required for a hash?
- A. Not reversible
- B. Few collisions
- C. Not vulnerable to a brute force attack
- D. Must use SALT
- E. Variable length input, fixed length output
- F. Minimum key length
Answer: A,E
Explanation:
Correct answers: Variable length input, fixed length output and Not reversible
https://en.wikipedia.org/wiki/Hash_function
A hash function is any function that can be used to map data of arbitrary size to fixed-size values. The values returned by a hash function are called hash values, hash codes, digests, or simply hashes. The values are used to index a fixed-size table called a hash table. Use of a hash function to index a hash table is called hashing or scatter storage addressing.
NEW QUESTION 138
Which one of the following uses three different keys, all of the same size?
- A. DES
- B. RSA
- C. 3DES
- D. AES
Answer: C
Explanation:
3DES
https://en.wikipedia.org/wiki/Triple_DES
Triple DES (3DES or TDES), officially the Triple Data Encryption Algorithm (TDEA or Triple DEA), is a symmetric-key block cipher, which applies the DES cipher algorithm three times to each data block.
NEW QUESTION 139
What best describes the shifting of each letter a fixed number of spaces to the left or right?
- A. Single substitution
- B. Bit shifting
- C. Multi substitution
- D. XOR
Answer: A
Explanation:
Single substitution
https://en.wikipedia.org/wiki/Substitution_cipher#Simple_substitution
Substitution of single letters separately-simple substitution-can be demonstrated by writing out the alphabet in some order to represent the substitution. This is termed a substitution alphabet. The cipher alphabet may be shifted or reversed (creating the Caesar and Atbash ciphers, respectively) or scrambled in a more complex fashion, in which case it is called a mixed alphabet or deranged alphabet.
NEW QUESTION 140
......
212-81 Exam Dumps - Free Demo & 365 Day Updates: https://realpdf.pass4suresvce.com/212-81-pass4sure-vce-dumps.html