Free 212-81 Exam Dumps Preview

CBC-MAC
https://en.wikipedia.org/wiki/CBC-MAC
A cipher block chaining message authentication code (CBC-MAC) is a technique for constructing a message authentication code from a block cipher. The message is encrypted with some block cipher algorithm in CBC mode to create a chain of blocks such that each block depends on the proper encryption of the previous block. This interdependence ensures that a change to any of the plaintext bits will cause the final encrypted block to change in a way that cannot be predicted or counteracted without knowing the key to the block cipher. Using in WPA2 for integrity check and provides security against a replay attack.

It maintains letter and word frequency
https://en.wikipedia.org/wiki/Frequency_analysis
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.
Frequency analysis is based on the fact that, in any given stretch of written language, certain letters and combinations of letters occur with varying frequencies. Moreover, there is a characteristic distribution of letters that is roughly the same for almost all samples of that language. For instance, given a section of English language, E, T, A and O are the most common, while Z, Q, X and J are rare. Likewise, TH, ER, ON, and AN are the most common pairs of letters (termed bigrams or digraphs), and SS, EE, TT, and FF are the most common repeats. The nonsense phrase "ETAOIN SHRDLU" represents the 12 most frequent letters in typical English language text. In some ciphers, such properties of the natural language plaintext are preserved in the ciphertext, and these patterns have the potential to be exploited in a ciphertext-only attack.

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.

128 bit and CCMP
Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (CCMP) is an encryption protocol that forms part of the 802.11i standard for wireless local area networks (WLANs), particularly those using WiMax technology. CCMP employs 128-bit keys and a 48-bit initialization vector that minimizes vulnerability to replay attacks.

Rijndael https://en.wikipedia.org/wiki/Advanced_Encryption_Standard The Advanced Encryption Standard (AES),
also known by its original name Rijndael. The algorithm described by AES is a symmetric-key algorithm, meaning the same key is used for both encrypting and decrypting the data.

Chi-Square Analysis
https://en.wikipedia.org/wiki/Chi-squared_test

A chi-squared test, is a statistical hypothesis test that is valid to perform when the test statistic is chi-squared distributed under the null hypothesis, specifically Pearson's chi-squared test and variants thereof.
Pearson's chi-squared test is used to determine whether there is a statistically significant difference between the expected frequencies and the observed frequencies in one or more categories of a contingency table. In cryptanalysis, the chi-squared test is used to compare the distribution of plaintext and (possibly) decrypted ciphertext. The lowest value of the test means that the decryption was successful with high probability. This method can be generalized for solving modern cryptographic problems.

https://en.wikipedia.org/wiki/FORK-256
FORK-256 was introduced at the 2005 NIST Hash workshop and published the following year.[6] FORK- 256 uses 512-bit blocks and implements preset constants that change after each repetition. Each block is hashed into a 256-bit block through four branches that divides each 512 block into sixteen 32-bit words that are further encrypted and rearranged

DSA
https://ru.wikipedia.org/wiki/DSA
The National Institute of Standards and Technology (NIST) proposed DSA for use in their Digital Signature Standard (DSS) in 1991, and adopted it as FIPS 186 in 1994. DSA is covered by U.S. Patent 5,231,668 , filed July 26, 1991 and now expired, and attributed to David W. Kravitz, a former NSA employee.

https://en.wikipedia.org/wiki/MD5
The MD5 message-digest algorithm is a widely used hash function producing a 128-bit hash value.

S-PAP
Shiva Password Authentication Protocol (S-PAP) - PAP with encryption for the usernames/passwords that are transmitted.

https://en.wikipedia.org/wiki/DES
The Data Encryption Standard 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.

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 stegan, meaning "covered or concealed", and -graphia meaning "writing".

The ciphertext block is encrypted then the ciphertext produced is XOR'd back with the plaintext to produce the current ciphertext block https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_feedback_(CFB) The cipher
feedback (CFB) mode, a close relative of CBC, makes a block cipher into a self-synchronizing stream cipher.

Substitution box where input bits are replaced
https://en.wikipedia.org/wiki/S-box
In cryptography, an S-box (substitution-box) is a basic component of symmetric key algorithms which performs substitution. In block ciphers, they are typically used to obscure the relationship between the key and the ciphertext -- Shannon's property of confusion.

Integrity. In information security, data integrity means maintaining and assuring the accuracy and completeness of data over its entire lifecycle. This means that data cannot be modified in an unauthorized or undetected manner.
An important application of 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.
SHA-1
https://en.wikipedia.org/wiki/SHA-1SHA-1(SecureHashAlgorithm1)isacryptographichashfunctionwhichtakesaninputandproducesa160-bit(20-byte)hashvalueknownasamessagedigest?typicallyrenderedasahexadecimalnumber,40digitslong.ItwasdesignedbytheUnitedStatesNationalSecurityAgency,andisaU.S.FederalInformationProcessingStandard.

2^56
https://en.wikipedia.org/wiki/Data_Encryption_Standard
The Data Encryption Standard (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.

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

Brute force
https://en.wikipedia.org/wiki/Brute-force_attack
A 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. A brute-force attack is a cryptanalytic attack that can, in theory, be used to attempt to decrypt any encrypted data (except for data encrypted in an information-theoretically secure manner). Such an attack might be used when it is not possible to take advantage of other weaknesses in an encryption system (if any exist) that would make the task easier.

RA (Registration Authority)
https://en.wikipedia.org/wiki/Registration_authority
Registration authorities exist for many standardsorganizations,suchasANNA(AssociationofNationalNumberingAgenciesforISIN),theObjectManagementGroup,W3C,IEEEandothers.Ingeneral,registrationauthoritiesallperformasimilarfunction,inpromotingtheuseofaparticularstandardthroughfacilitatingitsuse.Thismaybebyapplyingthestandard,whereappropriate,orbyverifyingthataparticularapplicationsatisfiesthestandard'stenants.Maintenanceagencies,incontrast,maychangeanelementinastandardbasedonsetrules?suchasthecreationorchangeofacurrencycodewhenacurrencyiscreatedorrevalued(i.e.TRLtoTRYforTurkishlira).TheObjectManagementGrouphasanadditionalconceptofcertifiedprovider,whichisdeemedanentitypermittedtoperformsomefunctionsonbehalfoftheregistrationauthority,underspecificprocessesandproceduresdocumentedwithinthestandardforsucharole.

Global deduction
https://en.wikipedia.org/wiki/Cryptanalysis
Global deduction -- the attacker discovers a functionally equivalent algorithm for encryption and decryption, but without learning the key.

CHAP https://en.wikipedia.org/wiki/Challenge-Handshake_Authentication_Protocol Challenge-Handshake
Authentication Protocol (CHAP) is an identity verification protocol that does not rely on sending a shared secret between the access-requesting party and the identity-verifying party (the authenticator). CHAP is based on a shared secret, but in order to authenticate, the authenticator sends a "challenge" message to the access-requesting party, which responds with a value calculated using a "one-way hash" function that takes as inputs the challenge and the shared secret. The authenticator checks the response against its own calculation of the expected hash value. If the values match, the authentication succeeds, otherwise it fails. Following the establishment of an authenticated connection, the authenticator may send a challenge to the access-requesting party at random intervals, to which the access-requesting party will have to produce the correct response.

Hash
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.

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".

Fibonacci Sequence
https://en.wikipedia.org/wiki/Fibonacci_number
In mathematics, the Fibonacci numbers, commonly denoted Fn, form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1. That is, F0 = 0, F1=1, Fn = Fn-1 + Fn-2; for n > 1.
The beginning of the sequence is thus:
0,1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144...

RC4
https://en.wikipedia.org/wiki/RC4
RC4 (Rivest Cipher 4 also known as ARC4 or ARCFOUR meaning Alleged RC4, see below) is a stream cipher. While it is remarkable for its simplicity and speed in software, multiple vulnerabilities have been discovered in RC4, rendering it insecure. It is especially vulnerable when the beginning of the output keystream is not discarded, or when nonrandom or related keys are used. Particularly problematic uses of RC4 have led to very insecure protocols such as WEP.
The key-scheduling algorithm is used to initialize the permutation in the array "S". "keylength" is defined as the number of bytes in the key and can be in the range 1 keylength 256, typically between 5 and 16, corresponding to a key length of 40 ?128 bits. First, the array "S" is initialized to the identity permutation. S is then processed for 256 iterations in a similar way to the main PRGA, but also mixes in bytes of the key at the same time.

Social engineering attack https://en.wikipedia.org/wiki/Social_engineering_(security) Social engineering is the psychological
manipulation of people into performing actions or divulging confidential information. This differs from social engineering within the social sciences, which does not concern the divulging of confidential information. A type of confidence trick for the purpose of information gathering, fraud, or system access, it differs from a traditional "con" in that it is often one of many steps in a more complex fraud scheme.

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

Collision https://en.wikipedia.org/wiki/Collision_(computer_science) A collision or clash is a situation that occurs
when two distinct pieces of data have the same hash value, checksum, fingerprint, or cryptographic digest.

Correct answers: Mersenne Primes
https://en.wikipedia.org/wiki/Mersenne_prime
Mersenne prime is a prime number that is one less than a power of two. That is, it is a prime number of the form M_n = 2^n 1 for some integer n. They are named after Marin Mersenne, a French Minim friar, who studied them in the early 17th century. If n is a composite number then so is 2^n 1. Therefore, an equivalent definition of the Mersenne primes is that they are the prime numbers of the form M_p = 2^p 1 for some prime p.