Test4Engine 212-81 Dumps PDF - 100% Passing Guarantee
212-81 Braindumps Real Exam Updated on Jul 30, 2023 with 200 Questions
NEW QUESTION # 12
Cylinder tool. Wrap leather around to decode. The diameter is the key. Used in 7th century BC by greek poet Archilochus.
- A. Caesar cipher
- B. Cipher disk
- C. Enigma machine
- D. Scytale
Answer: D
Explanation:
Scytale
https://en.wikipedia.org/wiki/Scytale
A scytale is a tool used to perform a transposition cipher, consisting of a cylinder with a strip of parchment wound around it on which is written a message. The ancient Greeks, and the Spartans in particular, are said to have used this cipher in 7th century BC to communicate during military campaigns.
The recipient uses a rod of the same diameter on which the parchment is wrapped to read the message. It has the advantage of being fast and not prone to mistakes-a necessary property when on the battlefield. It can, however, be easily broken. Since the strip of parchment hints strongly at the method, the ciphertext would have to be transferred to something less suggestive, somewhat reducing the advantage noted.
Incorrect answers:
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".
Enigma machine - is an encryption device developed and used in the early- to mid-20th century to protect commercial, diplomatic and military communication. It was employed extensively by Nazi Germany during World War II, in all branches of the German military.
Caesar cipher - (also known as Caesar's cipher, the shift cipher, Caesar's code or Caesar shift) is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on. The method is named after Julius Caesar, who used it in his private correspondence.
NEW QUESTION # 13
RFC 1321 describes what hash?
- A. SHA1
- B. MD5
- C. GOST
- D. RIPEMD
Answer: B
Explanation:
MD5
https://en.wikipedia.org/wiki/MD5
MD5 was designed by Ronald Rivest in 1991 to replace an earlier hash function MD4, and was specified in 1992 as RFC 1321.
NEW QUESTION # 14
Which of the following statements is most true regarding binary operations and encryption?
- A. They can form a part of viable encryption methods
- B. They are only useful as a teaching method
- C. They can provide secure encryption
- D. They are completely useless
Answer: A
Explanation:
They can form a part of viable encryption methods
for example - https://en.wikipedia.org/wiki/XOR_cipher
The XOR operator is extremely common as a component in more complex ciphers. By itself, using a constant repeating key, a simple XOR cipher can trivially be broken using frequency analysis. If the content of any message can be guessed or otherwise known then the key can be revealed. Its primary merit is that it is simple to implement, and that the XOR operation is computationally inexpensive. A simple repeating XOR (i.e. using the same key for xor operation on the whole data) cipher is therefore sometimes used for hiding information in cases where no particular security is required. The XOR cipher is often used in computer malware to make reverse engineering more difficult.
NEW QUESTION # 15
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 # 16
A digital document that contains a public key and some information to allow your system to verify where that key came from. Used for web servers, Cisco Secure phones, E-Commerce.
- A. Digital Certificate
- B. OCSP
- C. Payload
- D. Registration Authority
Answer: A
Explanation:
Digital Certificate
https://en.wikipedia.org/wiki/Public_key_certificate
A public key certificate, also known as a digital certificate or identity certificate, is an electronic document used to prove the ownership of a public key. The certificate includes information about the key, information about the identity of its owner (called the subject), and the digital signature of an entity that has verified the certificate's contents (called the issuer).
Incorrect answers:
OCSP - Provides certificate validation in real time and will let you know if it is valid or has been revoked.
Registration Authority (RA) - component of PKI that validates the identity of an entity requesting a digital certificate.
Payload - In computing and telecommunications, the payload is the part of transmitted data that is the actual intended message. Headers and metadata are sent only to enable payload delivery. In the steganography - information to be concealed and sent secretly, or the data covertly communicated;
NEW QUESTION # 17
You are studying classic ciphers. You have been examining the difference between single substitution and multi-substitution. Which one of the following is an example of a multi-alphabet cipher?
- A. Vigenere
- B. Caesar
- C. Rot13
- D. Atbash
Answer: A
Explanation:
Vigenere
https://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher
The Vigenere cipher is a 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.
First described by Giovan Battista Bellaso in 1553, the cipher is easy to understand and implement, but it resisted all attempts to break it until 1863, three centuries later. This earned it the description le chiffre indechiffrable (French for 'the indecipherable cipher'). Many people have tried to implement encryption schemes that are essentially Vigenere ciphers. In 1863, Friedrich Kasiski was the first to publish a general method of deciphering Vigenere ciphers.
NEW QUESTION # 18
In 1977 researchers and MIT described what asymmetric algorithm?
- A. EC
- B. DH
- C. AES
- D. RSA
Answer: D
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.
NEW QUESTION # 19
What advantage do symmetric algorithms have over asymmetric algorithms
- A. It is easier to implement them in software
- B. They are more secure
- C. They are faster
Answer: C
Explanation:
D It is easier to exchange keys
Explanation:
They are faster
Symmetric key encryption is much faster than asymmetric key encryption, because both the sender and the recipient of a message to use the same secret key.
NEW QUESTION # 20
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. Steganalysis
- D. Cryptography
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 # 21
Which one of the following uses three different keys, all of the same size?
- A. RSA
- B. DES
- C. AES
- D. 3DES
Answer: D
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 # 22
John is going to use RSA to encrypt a message to Joan. What key should he use?
- A. Joan's public key
- B. A shared key
- C. A random key
- D. Joan's private key
Answer: A
Explanation:
Joan's public key
https://en.wikipedia.org/wiki/RSA_(cryptosystem)
Suppose Joahn uses Bob's public key to send him an encrypted message. In the message, she can claim to be Alice but Bob has no way of verifying that the message was actually from Alice since anyone can use Bob's public key to send him encrypted messages. In order to verify the origin of a message, RSA can also be used to sign a message.
Suppose Alice wishes to send a signed message to Bob. She can use her own private key to do so. She produces a hash value of the message, raises it to the power of d (modulo n) (as she does when decrypting a message), and attaches it as a "signature" to the message. When Bob receives the signed message, he uses the same hash algorithm in conjunction with Alice's public key. He raises the signature to the power of e (modulo n) (as he does when encrypting a message), and compares the resulting hash value with the message's actual hash value. If the two agree, he knows that the author of the message was in possession of Alice's private key, and that the message has not been tampered with since.
NEW QUESTION # 23
Which of the following encryption algorithms relies on the inability to factor large prime numbers?
- A. MQV
- B. EC
- C. AES
- D. RSA
Answer: D
Explanation:
Correct answers: 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.
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.
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.
AES - Advanced Encryption Standard (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 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.
MQV - (Menezes-Qu-Vanstone) is an authenticated protocol for key agreement based on the Diffie-Hellman scheme. Like other authenticated Diffie-Hellman schemes, MQV provides protection against an active attacker. The protocol can be modified to work in an arbitrary finite group, and, in particular, elliptic curve groups, where it is known as elliptic curve MQV (ECMQV).
NEW QUESTION # 24
What is the formula m^e %n related to?
- A. Decrypting with RSA
- B. Encrypting with RSA
- C. Encrypting with EC
- D. Generating Mersenne primes
Answer: B
Explanation:
Encrypting with RSA
https://en.wikipedia.org/wiki/RSA_(cryptosystem)
RSA Encrypting a message m (number) with the public key (n, e) is calculated:
M' := m^e %n
Incorrect answers:
Decrypting with RSA:
M'' := m^d %n
Generation Mersenne primes:
Mn = 2^n - 1
Encrypting with Elliptic Curve (EC):
y^2 = x^3 + ax + b
NEW QUESTION # 25
Which of the following is the standard for digital certificates?
- A. RFC 2298
- B. CRL
- C. CA
- D. X.509
- E. 509
https://en.wikipedia.org/wiki/X.509 - F. 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.
Answer: D
NEW QUESTION # 26
All of the following are key exchange protocols except for____
- A. MQV
- B. ECDH
- C. DH
- D. AES
Answer: D
NEW QUESTION # 27
In which of the following password protection technique, random strings of characters are added to the password before calculating their hashes?
- A. Keyed Hashing
- B. Key Stretching
- C. Double Hashing
- D. Salting
Answer: D
Explanation:
Salting
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 new salt is randomly generated for each password. In a typical setting, the salt and the password (or its version after key stretching) are concatenated and processed with a cryptographic hash function, and the output hash value (but not the original password) is stored with the salt in a database. Hashing allows for later authentication without keeping and therefore risking exposure of the plaintext password in the event that the authentication data store is compromised.
Salts defend against a pre-computed hash attack, e.g. rainbow tables.Since salts do not have to be memorized by humans they can make the size of the hash table required for a successful attack prohibitively large without placing a burden on the users. Since salts are different in each case, they also protect commonly used passwords, or those users who use the same password on several sites, by making all salted hash instances for the same password different from each other.
NEW QUESTION # 28
Created by D. H. Lehmer. It is a classic example of a Linear congruential generator. A PRNG type of linear congruential generator (LCG) that operates in multiplicative group of integers modulo n. The basic algorithm is Xi+1=(aXi + c) mod m, with 0 ≤ Xi ≤ m.
- A. Blum Blum Shub
- B. Linear Congruential Generator
- C. Lehmer Random Number Generator
- D. Lagged Fibonacci Generator
Answer: C
Explanation:
Lehmer Random Number Generator
https://en.wikipedia.org/wiki/Lehmer_random_number_generator
The Lehmer random number generator (named after D. H. Lehmer), sometimes also referred to as the Park-Miller random number generator (after Stephen K. Park and Keith W. Miller), is a type of linear congruential generator (LCG) that operates in multiplicative group of integers modulo n. The general formula is:
where the modulus m is a prime number or a power of a prime number, the multiplier a is an element of high multiplicative order modulo m (e.g., a primitive root modulo n), and the seed X0 is coprime to m.
Other names are multiplicative linear congruential generator (MLCG) and multiplicative congruential generator (MCG).
NEW QUESTION # 29
If Bob is using asymmetric cryptography and wants to send a message to Alice so that only she can decrypt it, what key should he use to encrypt the message?
- A. Bob's private key
- B. Alice's private key
- C. Bob's public key
- D. Alice's public key
Answer: D
Explanation:
Alice's public key
https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange
In asymmetric (public key) cryptography, both communicating parties (i.e. both 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.
NEW QUESTION # 30
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. Temporal Key Integrity Protocol (TKIP)
- B. Wired Equivalent Privacy (WEP)
- C. Wi-Fi Protected Access (WPA)
- D. Wi-Fi Protected Access 2 (WPA2)
Answer: B
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 # 31
Storing private keys with a third party is referred to as what?
- A. Key storage
- B. Key caching
- C. Key escrow
- D. Key banking
Answer: C
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 # 32
Bruce Schneier is a well-known and highly respected cryptographer. He has developed several pseudo random number generators as well as worked on teams developing symmetric ciphers. Which one of the following is a symmetric block cipher designed in 1993 by Bruce Schneier team that is unpatented?
- A. Blowfish
- B. Pegasus
- C. SHA1
- D. AES
Answer: B
Explanation:
Blowfish
https://en.wikipedia.org/wiki/Blowfish_(cipher)
Blowfish is a symmetric-key block cipher, designed in 1993 by Bruce Schneier and included in many cipher suites and encryption products.
NEW QUESTION # 33
_____ uses at least two different shifts, changing the shift with different letters in the plain text.
- A. Caesar cipher
- B. Scytale
- C. multi-alphabet encryption
- D. Atbash
Answer: C
Explanation:
multi-alphabet encryption
https://en.wikipedia.org/wiki/Polyalphabetic_cipher
Two different shifts create two different alphabets.
For +1 and +2
Plaintext alphabet
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
2 ciphertext alphabets
B C D E F G H I J K L M N O P Q R S T U V W X Y Z A
C D E F G H I J K L M N O P Q R S T U V W X Y Z A B
Incorrect answers:
Scytale - transposition cipher
Caesar cipher - monoalphabetic cipher
Atbash - monoalphabetic cipher
NEW QUESTION # 34
......
212-81 Dumps With 100% Verified Q&As - Pass Guarantee or Full Refund: https://www.test4engine.com/212-81_exam-latest-braindumps.html
Latest 212-81 PDF Dumps & Real Tests Free Updated Today: https://drive.google.com/open?id=1Vb-xlR-C6jVzO6xYg99bUA3iXUDYEKU_