CRYALL
A
Before the application of the public-key cryptosystem each participant must generate a pair of keys A_ True B. False
An example of a technique that uses S-boxes that are both random and key dependent is ___________ , which starts with S-boxes filled with pseudorandom digits and then alters the contents using the key.
Blowfish
The earliest known and simplest use of a substitution cipher was called the __________ cipher and involved replacing each letter of the alphabet with the letter standing three places further down the alphabet.
Caesar
The input to the encryption algorithm is the XOR of the next 64 bits of plaintext and the preceding 64 bits of ciphertext" is a description of __________ mode
Cipher Black Chaining
Input is processed s bits at a time. Preceding ciphertext is used as input to the encryption algorithm to produce pseudorandom output, which is XORed with plaintext to produce next unit of ciphertext", is a description of the _________ mode of operation.
Cipher Feedback (CFB)
__________ seeks to make the relationship between the statistics of the ciphertext and the value of the encryption key as complex as possible so that even if the attacker can get some handle on the statistics of the ciphertext, the way in which the key was used to produce that ciphertext is so complex it is difficult to deduce the key.
Confusion
Hardware efficiency, software efficiency, preprocessing, random access, provable security, and simplicity are all advantages of __________ mode.
Counter
The __________ block cipher mode of operation is a general purpose block oriented transmission useful for high speed requirements.
Counter (CTR)
The most widely used cipher ever is the __________
Data Encryption Standard (DES)
The most widely used encryption scheme is based on the __________ adopted in 1977 by the National Bureau of Standards as Federal Information Processing Standard 46.
Data Encryption Standard (DES)
B
Electronic Codebook (ECB) is used for the secure transmission of single values A_ False B_ True
True/False ) DES uses a 56-bit block and a 64-bit key.
FALSE
True/False All other things being equal, smaller block sizes mean greater security.
FALSE
True/False Ciphertext generated using a computationally secure encryption scheme is impossible for an opponent to decrypt simply because the required information is not there.
FALSE
True/False Confusion seeks to make the statistical relationship between the plaintext and ciphertext as complex as possible in order to thwart attempts to deduce the key.
FALSE
True/False One criteria for an S-box is: "If two inputs to an S-box differ in exactly one bit, the outputs must also differ in exactly one bit
FALSE
True/False Security attacks are classified as either passive or aggressive.
FALSE
True/False Security services include access control, data confidentiality and data integrity, but do not include authentication.
FALSE
True/False Steganography renders the message unintelligible to outsiders by various transformations of the text.
FALSE
True/False Symmetric encryption is a form of cryptosystem in which encryption and decryption are performed using different keys. It is also known as non-conventional encryption.
FALSE
True/False The OSI security architecture was not developed as an international standard, therefore causing an obstacle for computer and communication vendors when developing security features.
FALSE
True/False The data integrity service inserts bits into gaps in a data stream to frustrate traffic analysis attempts.
FALSE
True/False The emphasis in dealing with active attacks is on prevention rather than detection.
FALSE
True/False The key schedule algorithm is more popular and has received more attention than S-box design.
FALSE
True/False The one-time pad has unlimited utility and is useful primarily for high-bandwidth channels requiring low security.
FALSE
True/False The process of converting from plaintext to ciphertext is known as deciphering or decryption.
FALSE
True/False The strict avalanche criterion and the bit independence criterion appear to weaken the effectiveness of the confusion function.
FALSE
True/False The vast majority of network based symmetric cryptographic applications make use of stream ciphers.
FALSE
True/False When using symmetric encryption it is very important to keep the algorithm secret.
FALSE
True/False: A cryptographically secure pseudorandom bit generator is defined as one that passes the least significant bit test.
FALSE
True/False: A number of Internet based applications have adopted two-key 3DES, including PGP and S/MIME.
FALSE
True/False: AES uses a Feistel structure.
FALSE
True/False: All other things being equal, smaller block sizes mean greater security.
FALSE
True/False: As with any block cipher, AES can be used to construct a message authentication code, and for this, only decryption is used.
FALSE
True/False: Cipher Feedback (CFB) is used for the secure transmission of single values.
FALSE
True/False: Cipher Feedback Mode conforms to the typical construction of a stream cipher.
FALSE
True/False: Confusion seeks to make the statistical relationship between the plaintext and ciphertext as complex as possible in order to thwart attempts to deduce the key.
FALSE
True/False: DES is a block cipher intended to replace AES for commercial applications.
FALSE
True/False: DES uses a 56-bit block and a 64-bit key.
FALSE
True/False: Examples of a pseudorandom function are decryption keys and nonces.
FALSE
True/False: In the Advanced Encryption Standard the decryption algorithm is identical to the encryption algorithm. 39) ______
FALSE
True/False: InvSubBytes is the inverse of ShiftRows.
FALSE
True/False: Once the plaintext is converted to ciphertext using the encryption algorithm the plaintext is then used as input and the algorithm is applied again.
FALSE
True/False: One criteria for an S-box is: "If two inputs to an S-box differ in exactly one bit, the outputs must also differ in exactly one bit.
FALSE
True/False: S-AES is the most widely used multiple encryption scheme.
FALSE
True/False: The XTS-AES standard describes a method of decryption for data stored in sector-based devices where the threat model includes possible access to stored data by the adversary.
FALSE
True/False: The key schedule algorithm is more popular and has received more attention than S-box design.
FALSE
True/False: The purpose of the Maurer's universal statistical test is to determine whether the number of ones and zeros in a sequence are approximately the same as would be expected for a truly random sequence.
FALSE
True/False: The sender is the only one who needs to know an initialization vector.
FALSE
True/False: The stream cipher is similar to the one-time pad with a difference being that a one-time pad uses a pseudorandom number stream and a stream cipher uses a genuine random number stream.
FALSE
True/False: The strict avalanche criterion and the bit independence criterion appear to weaken the effectiveness of the confusion function.
FALSE
True/False: The transformations AddRoundKey and InvMixColumn alter the sequence of bytes in State.
FALSE
True/False: The vast majority of network based symmetric cryptographic applications make use of stream ciphers.
FALSE
True/False: There are well-defined tests for determining uniform distribution and independence to validate that a sequence of numbers is random.
FALSE
In the United States, the release of student grade information is regulated by the __________
Family Educational Rights and Privacy Act (FERPA)
Many block ciphers have a __________ structure which consists of a number of identical rounds of processing and in each round a substitution is performed on one half of the data being processed, followed by a permutation that interchanges the two halves.
Feistel
B
In the AddRoundKey transformation the 128 b. of State are bitwise X0Red with the of the round key A. 64 bits B. 128 bits C. None of the other choices D. 512 bits E. 256 bits
___________ affects the sequence of bytes in State but does not alter byte contents and does not depend on byte contents to perform its transformation.
InvShiftRows
Operating systems typically provide a built-in mechanism for generating random numbers. For example, __________ uses mouse and keyboard activity, disk I/O operations, and specific interrupts.
Linux
The _________ transformation operates on each column individually. Each byte of a column is mapped into a new value that is a function of all four bytes in that column.
MixColumns
The first N - 1 rounds consist of four distinct transformation functions: SubBytes, ShiftRows, AddRoundKey, and __________ .
MixColumns
__________ is a technique in which an encryption algorithm is used multiple times.
Multiple Encryption
A
Multiple encryption means that once the plaintext is converted to ciphertext using the encryption algorithm the plaintext is then used as input and the algorithm is applied again. A. False B. True
__________ prevents either sender or receiver from denying a transmitted message. Thus, when a message is sent, the receiver can prove that the alleged sender in fact sent the message and when a message is received, the sender can prove that the alleged receiver in fact received the message.
Nonrepudiation
__________ is the use of a trusted third party to assure certain properties of a data exchange.
Notarization
The __________ standard describes a method of encryption for data stored in sector-based devices where the threat model includes possible access to stored data by the adversary. Some characteristics of this standard include: the ciphertext is freely available for an attacker, the data layout is not changed on the storage medium and in transit, and the same plaintext is encrypted to different ciphertexts at different locations.
P1619
The best known multiple letter encryption cipher is the __________ which treats digrams in the plaintext as single units and translates these units into ciphertext digrams.
Playfair
__________ algorithms are designed specifically and solely for the purpose of generating pseudorandom bit streams.
Purpose-built
The most important and widely used stream cipher is __________ .
RC4
__________ is a stream cipher designed in 1987 by Ron Rivest for RSA Security.
RC4
A
Random numbers play an important role in the use of encryption for various network security applications_ A_ False B_ True
The National Institute of Standards and Technology chose the __________ design as the winning candidate for AES.
Rijndael
A technique for hiding a secret message within a larger document or picture in such a way that others cannot discern the presence or contents of the hidden message is __________ .
Steganography
The forward substitute byte transformation, called _________ , is a simple table lookup.
SubBytes
__________ encryption is a form of cryptosystem in which encryption and decryption are performed using the same key.
Symmetric
TRUETrue/False: With true random sequences each number is statistically independent of other numbers in the sequence and therefore unpredictable.
TRUE
True/False A prime concern with DES has been its vulnerability to brute-force attack because of its relatively short key length.
TRUE
True/False A problem with the ideal block cipher using a small block size is that it is vulnerable to a statistical analysis of the plaintext.
TRUE
True/False A scheme known as a one-time pad is unbreakable because it produces random output that bears no statistical relationship to the plaintext.
TRUE
True/False All the techniques for providing security have two components: a security-related transformation on the information to be sent and some secret information shared by the two principals.
TRUE
True/False An advantage of key-dependent S-boxes is that because they are not fixed, it is impossible to analyze the S-boxes ahead of time to look for weaknesses.
TRUE
True/False As with Playfair, the strength of the Hill cipher is that it completely hides single letter frequencies
TRUE
True/False Authentication protocols and encryption algorithms are examples of security mechanisms.
TRUE
True/False Data origin authentication does not provide protection against the modification of data units.
TRUE
True/False Fast software encryption/decryption and ease of analysis are two considerations in the design of a Feistel cipher.
TRUE
True/False Greater complexity in the subkey generation algorithm should lead to greater difficulty of cryptanalysis.
TRUE
True/False If the bit-stream generator is a key-controlled algorithm the two users only need to share the generating key and then each can produce the keystream.
TRUE
True/False Information access threats intercept or modify data on behalf of users who should not have access to that data.
TRUE
True/False Monoalphabetic ciphers are easy to break because they reflect the frequency data of the original alphabet.
TRUE
True/False On average, half of all possible keys must be tried to achieve success with a brute-force attack.
TRUE
True/False Patient allergy information is an example of an asset with a high requirement for integrity.
TRUE
True/False Rotor machines are sophisticated precomputer hardware devices that use substitution techniques.
TRUE
True/False Symmetric encryption is used to conceal the contents of blocks or streams of data of any size, including messages, files, encryption keys, and passwords.
TRUE
True/False Symmetric encryption remains by far the most widely used of the two types of encryption.
TRUE
True/False The Feistel cipher structure, based on Shannon's proposal of 1945, dates back over a quarter of a century and is the structure used by many significant symmetric block ciphers currently in use.
TRUE
True/False The OSI security architecture provides a systematic framework for defining security attacks, mechanisms, and services.
TRUE
True/False The algorithm will produce a different output depending on the specific secret key being used at the time. The exact substitutions and transformations performed by the algorithm depend on the key.
TRUE
True/False The connection-oriented integrity service addresses both message stream modification and denial of service.
TRUE
True/False The field of network and Internet security consists of measures to deter, prevent, detect and correct security violations that involve the transmission of information.
TRUE
True/False The heart of a Feistel block cipher is the function F, which relies on the use of S-boxes.
TRUE
True/False The more critical a component or service, the higher the level of required availability.
TRUE
True/False The most widely used cipher is the Data Encryption Standard.
TRUE
True/False With the use of symmetric encryption, the principal security problem is maintaining the secrecy of the key.
TRUE
True/False: ) Compared to public-key ciphers such as RSA, the structure of AES and most symmetric ciphers is quite complex and cannot be explained as easily as many other cryptographic algorithms.
TRUE
True/False: A mode of operation is a technique for enhancing the effect of a cryptographic algorithm or adapting the algorithm for an application.
TRUE
True/False: A prime concern with DES has been its vulnerability to brute-force attack because of its relatively short key length.
TRUE
True/False: A problem with the ideal block cipher using a small block size is that it is vulnerable to a statistical analysis of the plaintext.
TRUE
True/False: A typical application of Output Feedback mode is stream oriented transmission over noisy channel, such as satellite communication.
TRUE
True/False: A widely used technique for pseudorandom number generation is an algorithm known as the linear congruential method.
TRUE
True/False: AES can be implemented very efficiently on an 8-bit processor.
TRUE
True/False: An advantage of key-dependent S-boxes is that because they are not fixed, it is impossible to analyze the S-boxes ahead of time to look for weaknesses.
TRUE
True/False: At each horizontal point, State is the same for both encryption and decryption.
TRUE
True/False: Cipher Block Chaining is a simple way to satisfy the security deficiencies of ECB.
TRUE
True/False: Fast software encryption/decryption and ease of analysis are two considerations in the design of a Feistel cipher.
TRUE
True/False: Given the potential vulnerability of DES to a brute-force attack, an alternative has been found.
TRUE
True/False: Greater complexity in the subkey generation algorithm should lead to greater difficulty of cryptanalysis.
TRUE
True/False: If the PRF does not generate effectively random 128-bit output values it may be possible for an adversary to narrow the possibilities and successfully use a brute force attack.
TRUE
True/False: If the bit-stream generator is a key-controlled algorithm the two users only need to share the generating key and then each can produce the keystream.
TRUE
True/False: It is possible to convert a block cipher into a stream cipher using cipher feedback, output feedback and counter modes.
TRUE
True/False: OFB mode requires an initialization vector that must be unique to each execution of the encryption operation.
TRUE
True/False: Random numbers play an important role in the use of encryption for various network security applications.
TRUE
True/False: The Feistel cipher structure, based on Shannon's proposal of 1945, dates back over a quarter of a century and is the structure used by many significant symmetric block ciphers currently in use.
TRUE
True/False: The Rijndael developers designed the expansion key algorithm to be resistant to known cryptanalytic attacks.
TRUE
True/False: The S-box is designed to be resistant to known cryptanalytic attacks.
TRUE
True/False: The XTS-AES mode is based on the concept of a tweakable block cipher.
TRUE
True/False: The heart of a Feistel block cipher is the function F, which relies on the use of S-boxes.
TRUE
True/False: The inverse add round key transformation is identical to the forward add round key transformation because the XOR operation is its own inverse.
TRUE
True/False: The longer the keyword the more difficult the cryptanalysis.
TRUE
True/False: The nonlinearity of the S-box is due to the use of the multiplicative inverse.
TRUE
True/False: The ordering of bytes within a matrix is by column.
TRUE
True/False: The principle requirement of random or pseudorandom number generation is that the generated number stream be unpredictable.
TRUE
True/False: The security of Blum, Blum, Shub is based on the difficulty of factoring n.
TRUE
True/False: The seed that serves as input to the PRNG must be secure for cryptographic applications.
TRUE
True/False: The true random number generator may simply involve conversion of an analog source to a binary output.
TRUE
True/False: There are no practical cryptanalytic attacks on 3DES.
TRUE
True/False: Three broad categories of cryptographic algorithms are commonly used to create PRNGs: symmetric block ciphers, asymmetric ciphers, and hash functions and message authentication codes.
TRUE
True/False: Virtually all encryption algorithms, both conventional and public-key, involve arithmetic operations on integers.
TRUE
A
The Diffie-Hellman algorithm depends on the difficulty of computing discrete logarithms for As effectiveness. A True B False
B
The National Institute of Standards and Technology chose the ________ design as the winning candidate for AES A. Feistel B. Rijndael C Daemen and Rijmen D None of the other choices
A
The S-box is designed to be resistant to known cryptanalytic attacks. A. True B. False
B
The _______ block cipher mode of operation is a general purpose block oriented transmission useful tor high speed requirements A. None of the other choices B. CTR C. CFB D. CBC
D
The _______ protocol enables two users to establish a secret key using a public.key scheme based on discrete logarithms A. None of the other choices B. Micali-Schnorr C. Miller-Rabin D. Diffie-Hellman E. Elgamal-Fraiser
D
The _________ is a block cipher intended to replace DES for commercial applications. It uses a 128-bit block size and a key size of 128, 192, or 256 bits. A. None of the other choices B. Advanced Decryption Standard C. Advanced Studies Standard D. Advanced Encryption Standard
A
The defense against the brute-force approach for RSA is to use a large key space. A True B False
A
The difficulty of attacking ________ is based on the difficulty of finding the prime factors of a composite number A. RSA B. None of the other choices C. GSA D. DSA
D
The distribution of a bits in a random number sequence should be________ , therefore the frequency of occurrence of ones and zeros should be approximately equal A streamed B reversed C None of the other choices D uniform E independent
C
The most important and widely used stream cipher is A. WPA B. WEP C. RC4 D. None of the other choice
C
The most significant characteristic of __________ is that if the same b-bit block of plaintext appears more than once in the message, it always produces the same ciphertext. A. OFB B. None of the other choices C. ECB D. CBC
Cryptographic systems are characterized along three independent dimensions: The type of operations used for transforming plaintext to ciphertext; The way in which the plaintext is processed; and __________ .
The number of keys used
A
The principle requirement of random or pseudo random number generation is that the generated number stream be unpredictable. A. True B. False
C
The protocol enables two users to establish a secret key using a public-key scheme based on discrete logarithms A. Elgamal-Fraiser B. None of the other choices C. Diffie-Hellman D. Miller-Rabin E. Micali-Schnorr
A
The scheme is a block cipher in which the plaintext and ciphertext are integers between 0 and n - 1 for some n A. RSA B. None of the other choices C. NSA D. DSA
A
The simplest mode of operation is the mode, in which plaintext is handled one block at a time and each block of plaintext is encrypted using the same key. A. ECB B. CTR C. None of the other choices D. CBC
B
The stream cipher is similar to the one-time pad with a difference being that a one-time pad uses a pseudo random number stream and a stream cipher uses a genuine random number stream. A. False B. True
E
Triple DES makes use of stages of the DES algorithm, using a total of two or three distinct keys. A 12 B 6 C None of the other choices D 9 E 3
One of the simplest and best known polyalphabetic ciphers is _________ cipher. In this scheme, the set of related monoalphabetic substitution rules consists of the 26 Caesar ciphers with shifts of 0 through 25. Each cipher is denoted by a key letter which is the ciphertext letter that substitutes for the plaintext letter a.
Vigenère
A
__________ of an algorithm to be f(n) if, for all n and all inputs of length n the execution of the algorithm takes at most f(n) steps. This is a common measure of the efficiency of an algorithm. A. time complexity B. one-way function C. timing attack D. OAEP
E
___________ affects the sequence of bytes in State but does not alter byte contents and does not depend on byte contents to perform its transformation A. ShiftRows B. None of the other choices C. InvSubBytes D. InvSubNibbles E. InvShiftfRows
In the context of network security, ___________ is the ability to limit and control the access to host systems and applications via communications links.
access control
An __________ attack attempts to alter system resources or affect their operation
active
An __________ is an assault on system security that derives from an intelligent act that is a deliberate attempt to evade security services and violate the security policy of a system.
attack
The __________ service is concerned with assuring the recipient that the message is from the source that it claims to be from. This service must also assure that the connection is not interfered with in such a way that a third party can masquerade as one of the two legitimate parties for the purposes of unauthorized transmission or reception.
authentication
A loss of __________ is the disruption of access to or use of information or an information system.
availability
A change in one bit of the plaintext or one bit of the key should produce a change in many bits of the ciphertext. This is referred to as the __________ effect.
avalanche
The __________ criterion is defined as: "An S-box satisfies GA of order y if, for a 1-bit input change, at least y output bits change."
avalanche (GA)
A
(Choose 1 answer) The National Institute of Standards and Technology chose the design as the winning candidate for AES A. Rijndael B. Daemen and Rijmen C. Feistel D. None of the other choices
B
(Choose 1 answer) The block cipher mode of operation is a general purpose block oriented transmission useful for high speed requirements. A. None of the other choices B. CTR C. CBC D. CFB
A
(Choose 1 answer) The security of Blum, Blum, Shub is based on the difficulty of factoring n A_ True B_ False
A more efficient implementation can be achieved for a 32-bit processor if operations are defined on _________ words.
32-bit
The AES key expansion algorithm takes as input a four-word (16-byte) key and produces a linear array of __________ words (176 bytes).
44
C
A more efficient implementation can be achieved for a 32-bit processor if operations are defined on A. 128-bit B. 64-bit C. 32-bit D. None of the other choices
B
A public-key encryption scheme has __________ ingredients. A. None of the other choices B. 6 C. 8 D. 4 E. 2
B
A(n) ________ is a technique for enhancing the effect of a cryptographic algorithm or adapting the algorithm for an application A type of operation B mode of operation C operation tool D None of the other choices
A
AES can be implemented very efficiently on an 8-bit processor A. TRUE B. FALSE
A
AES is relying on a Feistel structure. A. False B. True
The standard decryption round has the structure InvShiftRows, InvSubBytes, __________, InvMixColumns.
AddRoundKey
__________ is a block cipher intended to replace DES for commercial applications. It uses a 128-bit block size and a key size of 128, 192, or 256 bits.
Advanced Encryption Standard (AES)
B
An algorithm that is used to produce an open-ended sequence of bits is referred to as a A. None of the other choices B. PRNG C. TRNG D. PRF
A
Asymmetric algorithms rely on one key for encryption and a different but related key for decryption. A True B. False
A stream of pseudorandom numbers should exhibit two forms of unpredictability: forward and __________ .
backward
The __________ criterion states that output bits j and k should change independently when any single input bit i is inverted for all i, j and k.
bit independence
A _________ is an encryption/decryption scheme in which a block of plaintext is treated as a whole and used to produce a ciphertext block of equal length.
block cipher
A __________ cipher processes the input one block of elements at a time producing an output block for each input block whereas a __________ cipher processes the input elements continuously producing output one element at a time.
block, stream
The two types of attack on an encryption algorithm are cryptanalysis based on properties of the encryption algorithm, and _________ which involves trying all possible keys.
brute-force
The four separate functions of the Advanced Encryption Standard are: permutation, arithmetic operations over a finite field, XOR with a key, and __________
byte substitution
The plaintext of a sector or data unit is organized in to blocks of 128 bits. For encryption and decryption, each block is treated independently. The only exception occurs when the last block has less than 128 bits. In that case the last two blocks are encrypted/decrypted using a ___________ technique instead of padding.
ciphertext-stealing
An encryption scheme is said to be __________ if the cost of breaking the cipher exceeds the value of the encrypted information and the time required to break the cipher exceeds the useful lifetime of the information.
computationally secure
The protection afforded to an automated information system in order to attain the applicable objectives of preserving the integrity, availability and confidentiality of information system resources" is the definition of
computer security
The requirements for encrypting stored data, also referred to as ___________ , differ somewhat from those for transmitted data.
data at rest
Two specific authentication services defined in X.800 are peer entity authentication and _________ authentication.
data origin
The rationale behind __________ cryptanalysis is to observe the behavior of pairs of text blocks evolving along each round of the cipher instead of observing the evolution of a single text block.
differential
In ___________ the statistical structure of the plaintext is dissipated into long-range statistics of the ciphertext. This is achieved by having each plaintext digit affect the value of many ciphertext digits.
diffusion
The simplest mode of operation is the ___________ mode, in which plaintext is handled one block at a time and each block of plaintext is encrypted using the same key.
electronic codebook
The most significant characteristic of __________ is that if the same b-bit block of plaintext appears more than once in the message, it always produces the same ciphertext.
electronic codebook mode (ECB)
Irreversible __________ mechanisms include hash algorithms and message authentication codes, which are used in digital signature and message authentication applications.
encipherment
The __________ is drawn from the physical environment of the computer and could include things such as keystroke timing patterns, disk electrical activity, mouse movements, and instantaneous values of the system clock.
entropy source
The __________ criterion is defined as: "An S-box satisfies GA of order y if, for a 1-bit input change, at least y output bits change."
guaranteed avalanche (GA)
wo criteria used to validate that a sequence of numbers is random are uniform distribution and __________ .
independence
A loss of _________ is the unauthorized modification or destruction of information.
integrity
A polynomial m(x) is called __________ if and only if m(x) cannot be expressed as a product of two polynomials, both of degree lower than that of m(x).
irreducible
The cipher consists of N rounds, where the number of rounds depends on the __________
key length
Two areas of concern regarding the level of security provided by DES are the nature of the algorithm and the __________
key size
Two areas of concern regarding the level of security provided by DES are the nature of the algorithm and the __________ .
key size
In a stream cipher structure a key is input to a pseudorandom bit generator that produces a stream of 8-bit numbers that are apparently random. The output of the generator, called a ___________ , is combined one byte at a time with the plaintext stream using the bitwise exclusive-OR operation.
keystream
Two important methods of cryptanalysis are differential cryptanalysis and _________ cryptanalysis.
linear
Two important methods of cryptanalysis are differential cryptanalysis and _________ cryptanalysis. 19) _____________
linear
A __________ is a technique for enhancing the effect of a cryptographic algorithm or adapting the algorithm for an application, such as applying a block cipher to a sequence of data blocks or a data stream.
mode of operation
The _________ must be a data block that is unique to each execution of the encryption operation and may be a counter, a timestamp, or a message number.
nonce
The task of making large quantities of random keys on a regular basis and distributing a key of equal length to both sender and receiver for every message sent are difficulties of the __________ scheme.
one-time pad
Five modes of operation have been standardized by NIST for use with symmetric block ciphers such as DES and AES: electronic codebook mode, cipher block chaining mode, cipher feedback mode, __________, and counter mode.
output feedback mode (OFB)
A _________ attack attempts to learn or make use of information from the system but does not affect system resources.
passive
A fundamental requirement of the RSA public-key encryption scheme is the ability to generate _________ numbers.
prime
An example of a finite field is the set Zp consisting of all the integers {0, 1, . . . , p - 1}, where p is a __________ and in which arithmetic is carried out modulo p.
prime number
If the algorithm is good the resulting sequences will pass many reasonable tests of randomness. These numbers are referred to as ___________ numbers.
pseudorandom
Typically the __________ takes as input a seed plus some context specific values such as a user ID or an application ID.
pseudorandom function (PRF)
An algorithm that is used to produce an open-ended sequence of bits is referred to as a ___________ .
pseudorandom number generator (PRNG)
The simplest transposition cipher is the _________ technique in which the plaintext is written down as a sequence of diagonals and then read off as a sequence of rows.
rail fence
Two distinct requirements for a sequence of random numbers are unpredictability and __________ .
randomness
The __________ consist of a set of independently rotating cylinders through which electrical pulses can flow. Each cylinder has 26 input pins and 26 output pins with internal wiring that connects each input pin to a unique output pin.
rotor machines
The purpose of the __________ test is to determine whether the number of runs of ones and zeros of various lengths is as expected for a random sequence.
runs
A ___________ is any process, or a device incorporating such a process, that is designed to detect, prevent, or recover from a security attack. Examples are encryption algorithms, digital signatures and authentication protocols.
security mechanism
The mix column transformation combined with the __________ transformation ensures that after a few rounds all output bits depend on all input bits.
shift row
Viruses and worms are two examples of _________ attacks. Such attacks can be introduced into a system by means of a disk that contains the unwanted logic concealed in otherwise useful software. They can also be inserted into a system across a network.
software
A __________ cipher can operate in real time and eliminates the need to pad a message to be an integral number of blocks.
stream
A __________ is a symmetric encryption algorithm in which ciphertext output is produced bit-by-bit or byte-by-byte from a stream of plaintext input.
stream cipher
The __________ criterion states that any output bit j of an S-box should change with probability 1/2 when any single input bit i is inverted for all i,j.
strict avalanche
AES processes the entire data block as a single matrix during each round using __________ and permutation.
substitutions
The cryptographic strength of a Feistel cipher derives from three aspects of the design: the function F, the key schedule algorithm, and __________
the number of rounds
The cryptographic strength of a Feistel cipher derives from three aspects of the design: the function F, the key schedule algorithm, and __________ .
the number of rounds
A _________ attack exploits the fact that an encryption or decryption algorithm often takes slightly different amounts of time on different inputs.
timing
All encryption algorithms are based on two general principles: substitution and __________ .
transposition
One of the most widely used multiple-encryption scheme is __________ .
triple DES
An encryption scheme is __________ secure if the ciphertext generated by the scheme does not contain enough information to determine uniquely the corresponding plaintext, no matter how much ciphertext is available.
unconditionally
