Exploring Computer Security Concepts

Define the term 'attack surface' in the context of computer security.

• The attack surface is the amount of data stored on a device.

• The attack surface refers to the total number of users in a network.

• The attack surface is the sum of the different points (attack vectors) in a given computing device or network that are accessible to an unauthorized user.

• The attack surface is the software used to protect a network from attacks.

What is Euclid's algorithm used for?

• Finding the square root of a number.

• Finding the greatest common divisor (GCD) of two integers.

• Calculating the area of a triangle.

• Sorting a list of numbers.

Describe the difference between groups, rings, and fields in algebraic structures.

• Groups require multiplicative inverses, rings do not, and fields have only one operation.

• Groups have one operation, rings have two operations with specific properties, and fields are rings with multiplicative inverses for non-zero elements.

• Groups and rings are the same, while fields are a special case of groups.

• Groups have two operations, rings have one operation, and fields have no operations.

What are the main features of the Data Encryption Standard (DES)?

• 8 rounds of processing

• 32-bit block size

• 128-bit key length

• Main features of DES include 56-bit key length, 64-bit block size, 16 rounds of processing, and use of substitution and permutation.

How does the Advanced Encryption Standard (AES) improve upon DES?

• AES relies on a simpler encryption algorithm than DES.

• AES offers stronger security and a more complex encryption process than DES.

• AES is less efficient in processing than DES.

• AES uses a shorter key length than DES.

What is a stream cipher, and how does RC4 function as one?

• A stream cipher is a type of encryption that only works with images, and RC4 is specifically designed for video files.

• A stream cipher is a method of encryption that processes data one bit at a time, and RC4 functions as one by generating a pseudo-random key stream that is XORed with the plaintext.

• A stream cipher encrypts data in blocks of 64 bits, and RC4 uses a fixed key for encryption.

• RC4 is a block cipher that processes data in 128-bit chunks and does not use a key stream.

List and explain the different cipher block modes of operation.

• 1. ECB (Electronic Codebook): Each block is encrypted independently. Simple but not secure for large data. 2. CBC (Cipher Block Chaining): Each block is XORed with the previous ciphertext block before encryption. Provides better security. 3. CFB (Cipher Feedback): Converts a block cipher into a self-synchronizing stream cipher. 4. OFB (Output Feedback): Similar to CFB but generates keystream blocks independently. 5. CTR (Counter): Turns a block cipher into a stream cipher by encrypting a counter value. Allows parallel processing.

• XOR (Exclusive OR): A method that combines two bits to produce a single bit, not a cipher mode.

• RSA (Rivest-Shamir-Adleman): A public-key cryptosystem used for secure data transmission, not a block mode.

• SHA (Secure Hash Algorithm): A family of cryptographic hash functions, not related to block ciphers.

What is the significance of using public key infrastructure (PKI) in securing communications?

• PKI helps in improving network speed.

• PKI is primarily for data compression.

• PKI provides a framework for creating, managing, and distributing digital certificates.

• PKI is used to manage user passwords.

Explain the concept of a digital signature and its importance in cybersecurity.

• A digital signature is a type of malware that targets sensitive information.

• A digital signature is a cryptographic technique that validates the authenticity and integrity of a message or document.

• A digital signature is a unique identifier for a user, used for tracking online activity.

• A digital signature is a method of encrypting data to ensure confidentiality.

What are the key differences between symmetric and asymmetric encryption?

• Symmetric encryption uses the same key for encryption and decryption, while asymmetric encryption uses a pair of keys (public and private).

• Symmetric encryption requires more computational power than asymmetric encryption.

• Symmetric encryption is slower than asymmetric encryption.

• Asymmetric encryption is used for encrypting large files, while symmetric encryption is for small data.