WorksheetsSYMMETRIC KEY CRYPTOGRAPHY (Assignment 2)
Total questions: 50
Worksheet time: 26mins
What is the main purpose of the Data Encryption Standard (DES)?
To ensure data integrity through hashing.
To provide data confidentiality through encryption.
To facilitate faster data transmission.
To provide user authentication through passwords.
How many rounds does DES use for encryption?
12
8
16
20
What is the key size used in DES?
64 bits
128 bits
32 bits
56 bits
Explain the difference between symmetric and asymmetric encryption.
Symmetric encryption is only used for digital signatures.
Symmetric encryption uses one key for both encryption and decryption, while asymmetric encryption uses a pair of keys (public and private) for these processes.
Symmetric encryption uses two keys for encryption and decryption.
Asymmetric encryption is faster than symmetric encryption for all data sizes.
What is the primary advantage of using Advanced Encryption Standard (AES) over DES?
AES is faster than DES due to simpler algorithms.
AES uses a fixed key length of 56 bits.
AES offers stronger security due to longer key lengths.
DES is more widely supported in legacy systems.
How many rounds does AES use for 128-bit keys?
12
10
8
14
What are the key sizes supported by AES?
128, 256, and 512 bits
128, 192, and 256 bits
64, 128, and 192 bits
128, 192, and 512 bits
Describe the structure of an AES block.
An AES block is a 256-bit data structure organized as a 2x16 matrix of bytes.
An AES block is a 64-bit data structure organized as an 8x8 matrix of bits.
An AES block is a 128-bit data structure organized as a 4x4 matrix of bytes.
An AES block is a 128-bit data structure organized as a single row of 16 bytes.
What is the main characteristic of the RC4 stream cipher?
RC4 encrypts data in blocks of 128 bits.
RC4 requires a public key for encryption.
RC4 uses a fixed key for encryption.
RC4 generates a pseudo-random key stream that is XORed with the plaintext.
How does the key scheduling algorithm work in RC4?
The key scheduling algorithm in RC4 initializes a state array and permutes it using the key.
The algorithm only uses a fixed key without any permutation.
The key scheduling algorithm encrypts the data directly.
It generates random keys without using a state array.
What is the significance of the S-box in DES?
The S-box is irrelevant to the security of DES.
The S-box is used for key generation in DES.
The S-box provides non-linearity and enhances security in the DES encryption process.
The S-box only provides linear transformations in DES.
Explain the concept of diffusion in cryptography.
Diffusion is the technique of generating random keys for encryption purposes.
Diffusion is the process of encrypting plaintext into ciphertext without any transformation.
Diffusion refers to the method of compressing data to reduce its size in cryptography.
Diffusion is the process of spreading the influence of plaintext bits across ciphertext bits in cryptography.
What is a potential vulnerability of using DES?
Vulnerability to man-in-the-middle attacks due to lack of authentication.
Vulnerability to side-channel attacks due to weak encryption algorithms.
Vulnerability to brute-force attacks due to small key size.
Vulnerability to replay attacks due to insufficient message integrity checks.
How does AES ensure security against differential cryptanalysis?
AES relies solely on key length for security.
AES employs linear transformations to enhance security.
AES uses a single round of encryption to ensure security.
AES ensures security against differential cryptanalysis through its use of multiple rounds, non-linear S-boxes, and mixing operations that obscure input-output relationships.
What is the role of the initialization vector (IV) in encryption algorithms?
The IV is used to store the encryption key securely.
The IV is a fixed value that remains constant for all encryptions.
The IV compresses the data before encryption.
The IV ensures randomness in encryption, enhancing security.
What is the primary function of the key expansion process in AES?
To generate a single key for encryption.
To provide a method for key exchange between parties.
To create a set of round keys from the original key.
To compress the data before encryption.
What is the main purpose of the Feistel structure in cryptographic algorithms?
To ensure that the encryption process is reversible.
To provide a method for generating random keys.
To enhance the speed of encryption.
To create a non-linear transformation of the data.
How does the use of a salt enhance password security?
It makes the password shorter and easier to remember.
It adds randomness to the password before hashing, preventing pre-computed attacks.
It encrypts the password directly.
It allows for faster password verification.
What is the key length of the Data Encryption Standard (DES)?
64 bits
56 bits
128 bits
32 bits
How many rounds does the DES encryption process consist of?
16
12
10
20
What is the purpose of the initial permutation (IP) in DES?
To generate keys
To rearrange bits
To discard bits
To encrypt the data
In DES, how is the 56-bit key derived from the initial 64-bit key?
By adding bits
By discarding every 8th bit
By reversing the bits
By shifting bits
What is the function of the S-Box in the DES encryption process?
To permute the bits
To generate the final output
To perform substitution
To expand the key
What does Triple DES (3DES) use to enhance security?
A longer key
Multiple rounds of DES
A larger block size
Different algorithms
What is the block size used in the Advanced Encryption Standard (AES)?
64 bits
128 bits
256 bits
512 bits
How many rounds does AES perform with a 256-bit key?
16
10
12
14
Which step is NOT part of the AES encryption process?
MixColumns
Key Generation
ShiftRows
SubBytes
What is the purpose of the Add Round Key step in AES?
To mix columns
To shift rows
To substitute bytes
To XOR with the round key
What is the main advantage of AES over DES?
It is faster
It is less secure
It has a longer key length
It is easier to implement
In AES, how is the data organized for processing?
In a grid
In rows only
In a linear format
In columns only
What is the role of the Inverse MixColumns step in AES decryption?
To shift rows back
To reverse the mixing of columns
To substitute bytes
To add round keys
What is the key size options available in AES?
192, 256, 512 bits
64, 128, 256 bits
128, 192, 256 bits
128, 256, 512 bits
What is the final step in the DES encryption process?
Key transformation
S-Box substitution
Final Permutation
Expansion Permutation
By using this type of encryption algorithms, data is converted to a form that cannot be understood by anyone who does not possess the secret key to decrypt it
Symmetric
Asymmetric
Is a type of encryption where only one key (a secret key) is used to both encrypt and decrypt electronic information.
Look at the example of encryption in the image and select the correct answer.
Asymmetric
Symmetric
Write at least 3 examples of symmetric encryption algorithms:
In “modern” computing, (a) was the first standardized cipher for securing electronic communications, and is used in variations
The most commonly used symmetric algorithm is the (a) , which was originally known as Rijndael. This is the standard set by the U.S. National Institute of Standards and Technology in 2001 for the encryption of electronic data announced in U.S.
This type of cryptography techniques allow for extremely secure communication between two parties.
Symmetric
Asymmetric
These two keys are separate but equal, and they're both required to decode a message. If you have only one, decryption is impossible.
Selec the correct answer.
Asymmetric
Symmetric
Some examples of where symmetric cryptography is used are:
Select one of the "pros" of Asymmetric Encryption
Vulnerabilities
Speed
Security
Select one of the "pros" of Symmetric Encryption
Vulnerabilities
Speed
Transparency
The system of congruences: x≡2mod3 x≡3mod5 x≡2mod7 has a unique solution modulo:
15
35
105
10
What is the greatest common divisor (GCD) of 56 and 98 using Euclid's algorithm?
14
7
28
21
To hide the relationship between the ciphertext and the key is known as
Diffusion
Confusion
Substitution
Addition
a ≡ b (mod n) this implies
Congruence Relationship
Greatest Common Divisor
Associative Relationship
Commutative relationship
Find the gcd of 42823 and 6409
17
15
1
0
This is an example of
SP Networks
Feistel Cipher
Hash Algorithm
Hill Cipher
What is the formula for Euclidean algorithm?
GCD (m,n) = GCD (n, m mod n)
GCD(m,n,o,p) = GCD (m, m mod n, o, p mod o)
LCM (m,n,o,p) = LCM (m, m mod n, o, p mod o)
