Podcast
Questions and Answers
Which of the following accurately describes the Data Encryption Standard (DES)?
Which of the following accurately describes the Data Encryption Standard (DES)?
What is the primary goal of diffusion in cipher design?
What is the primary goal of diffusion in cipher design?
Which statement best describes collision-resistant hashing algorithms?
Which statement best describes collision-resistant hashing algorithms?
What are two key principles of cipher design emphasized in cryptography?
What are two key principles of cipher design emphasized in cryptography?
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What distinguishes Advanced Encryption Standard (AES) from DES?
What distinguishes Advanced Encryption Standard (AES) from DES?
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What term describes the entity attempting to bypass security measures?
What term describes the entity attempting to bypass security measures?
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Which of the following is NOT a goal of Information Security?
Which of the following is NOT a goal of Information Security?
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What is an example of a systematic artifact that exposes a user or system to a threat?
What is an example of a systematic artifact that exposes a user or system to a threat?
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What does the CIA model stand for in Information Security?
What does the CIA model stand for in Information Security?
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What type of cipher uses a fixed shift to encode messages?
What type of cipher uses a fixed shift to encode messages?
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Which of the following is a source of vulnerability?
Which of the following is a source of vulnerability?
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In shared key cryptography, what is essential for both parties?
In shared key cryptography, what is essential for both parties?
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What is NOT a strategy for dealing with attacks in Information Security?
What is NOT a strategy for dealing with attacks in Information Security?
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What does cryptography primarily focus on?
What does cryptography primarily focus on?
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Which statement best describes a chosen-plaintext attack?
Which statement best describes a chosen-plaintext attack?
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What distinguishes unconditional security from conditional security?
What distinguishes unconditional security from conditional security?
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What type of attack involves the adversary only having access to ciphertext?
What type of attack involves the adversary only having access to ciphertext?
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How does HMAC enhance the security of MAC?
How does HMAC enhance the security of MAC?
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What does a digital signature provide in relation to a document?
What does a digital signature provide in relation to a document?
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What is the main flaw in traditional MAC implementations?
What is the main flaw in traditional MAC implementations?
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What is the purpose of an encryption algorithm?
What is the purpose of an encryption algorithm?
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Study Notes
Security Terms
- Adversary: Any entity attempting to bypass security measures, varying in goals and expertise.
- Risk: Valuable resources susceptible to misuse, including data, time, confidence, trust, and reputation.
- Threat: A specific way an attacker can compromise a system, such as an attacker's ability or objective.
- Threat Model: A compilation of threats deemed significant for a specific environment.
- Vulnerability: A system flaw exposing users, data, or the system itself to a threat. This can arise from faulty software/hardware, poor design, inadequate policy/configuration, system misuse, or unintended use.
- Attack: An attempt to exploit a vulnerability.
- Compromise: A successful attack.
- Trust: The level of anticipated appropriate behavior from an entity.
- Trust Model: Defines who can perform what actions within a specific environment.
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CIA Model (Confidentiality, Integrity, Availability): Ensures:
- Confidentiality: Information is accessible solely to authorized individuals.
- Integrity: System data remains accurate, free from unauthorized modifications.
- Availability: Information or services are accessible when needed.
Information Security Goals
- To prevent misuse, but not hinder legitimate actions.
- Strategies to manage attacks:
- Prevention: Prohibit attacks (e.g., firewalls).
- Detection: Identify ongoing attacks and generate alerts (e.g., intrusion detection).
- Recovery: Restore from attacks (e.g., backups).
Cryptography
- Caesar Cipher (ROT13): A simple substitution cipher where each letter is shifted thirteen positions down the alphabet. It's breakable due to its fixed shift pattern.
- Substitution Cipher: Replaces each letter with a different character or symbol. Breakable by analyzing letter frequencies and patterns.
- Polyalphabetic Cipher (Vigenere): Uses a keyword to shift letters by different amounts, making it more robust.
- Shared Key Cryptography (Symmetric Key Cryptography): Both sender and receiver utilize the same key for encryption and decryption.
- "Unbreakable" Cipher (One-Time Pad): Theoretically provides perfect security, but requires a unique random key as long as the message, making it impractical for everyday use.
- Kerckhoffs' Principles: These principles state that the security of a cryptosystem should rely on the secrecy of the key, not the algorithm itself.
DES and AES
- DES (Data Encryption Standard): A block cipher using an 8-byte input and an 8-byte key (56 bits + 8 parity bits).
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AES (Advanced Encryption Standard): A replacement for DES, a widely accepted symmetric key cipher. Features:
- Variable key lengths for flexibility.
- Compact code and memory footprint.
Cipher Types
- Block Ciphers: Process input in fixed-size blocks.
- Stream Ciphers: Encrypt input as a continuous stream, typically bitwise.
Cipher Design Principles
- Confusion: Make the relationship between input and output as complex (non-linear) as possible, often achieved through substitution (e.g., S-box).
- Diffusion: Spread the influence of each input bit across multiple output bits, achieved through permutation (e.g., Feistel structure).
Birthday Attacks
- A class of brute-force attacks exploiting the likelihood of collisions in hash functions.
Hashing Algorithms
- One Way: Computationally difficult to reverse (h()) - meaning it's virtually impossible to go from the hash output back to the original input.
- Collision Resistant: Difficult to find two distinct inputs (x1 and x2) that produce the same hash output (h(x1) == h(x2)).
Hash Functions as Authenticators
- Hash functions can be used to verify data integrity. Any change to the data will result in a different hash, indicating tampering.
Cryptography Basics
- Cryptography: The art and science of creating and using cryptosystems.
- Cryptosystem: A method for disguising (encrypting) plain text messages so only authorized individuals can decipher them (decrypt).
- Cryptanalysis: The art and science of breaking cryptosystems.
- Cryptology: The combined study of cryptography and cryptanalysis.
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Encryption Algorithm: An algorithm for making content unreadable to unauthorized users.
- E(plaintext, key) = ciphertext (encryption)
- D(ciphertext, key) = plaintext (decryption)
- The algorithm is typically public knowledge, while the key is private, adhering to the "principle of open design."
- Unconditional Security: A system that provides provable guarantees of security regardless of an attacker's computational power.
- Conditional/Computational Security: Security relies on limitations of an attacker's computational resources or certain hardness assumptions.
- Ciphertext-Only Attack: An attacker only has access to ciphertext and attempts to deduce the underlying plaintext.
- Known-Plaintext Attack: The attacker knows one or more pairs of ciphertext/plaintext encrypted with the same key, trying to determine the plaintext of other ciphertext.
- Chosen-Plaintext Attack: The attacker can obtain the encryption of any plaintext and attempts to determine the plaintext of different ciphertext.
- Chosen-Ciphertext Attack: The attacker can obtain the plaintext of any ciphertext except the one they want to decrypt.
- Hash Chain: Chains together multiple hash values to offer enhanced security.
- MAC (Message Authentication Code): Used to authenticate content and verify data integrity, but is susceptible to attacks where attackers might add new content.
- HMAC (Hash-based Message Authentication Code): A collision-resistant MAC where an attacker cannot compute a correct digest without knowing the key (K).
Encryption and Digital Signatures
- Private Key Encryption (Symmetric Key Encryption):* Both the sender and receiver use the same key for encryption and decryption.
- Digital Signatures:* Digitally replicate physical signatures, associating a private key with a document. They ensure authenticity and non-repudiation (proof of origin).
Secret Key vs. Public Key Cryptography
- Secret Key Cryptography (Symmetric Key Cryptography): Both sender and receiver use the same key.
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Public Key Cryptography (Asymmetric Key Cryptography): Uses two separate but mathematically related keys:
- A public key: Used to encrypt data, meaning anyone can encrypt data.
- A private key: Used to decrypt data, meaning only the owner of the private key can decrypt.
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Description
Test your knowledge on essential cybersecurity terminology. This quiz covers important concepts like adversaries, vulnerabilities, threats, and the CIA model. Understand the language of security and how these terms relate to protecting information and systems.