Network Security and Cryptography Vocabulary

Comprehensive vocabulary flashcards covering network security appliances, tools, design strategy, cryptography, and social engineering based on the lecture transcript.

Firewall

A device that blocks or passes network traffic based on a set of rules.

Intrusion Detection (Prevention) System (IDS/IPS)

A device that scans network traffic and creates an alert if suspicious activity is identified.

Proxy Server

A device that makes a request on behalf of another device.

Virtual Private Network (VPN)

A system that encrypts traffic in order to “Tunnel” across another network.

Packet Filters

A type of firewall that operates at the Delivery and Transport Layer to get rid of obvious traffic first with high efficiency.

Circuit level Gateways

Firewalls that provide session protection and enhanced NAT.

Application Level firewalls

Layer 7 firewalls that are computationally expensive and use pattern matching and context.

Stateful multilayer inspection firewalls

Firewalls that use a combination of packet filtering, circuit level gateways, and application level methods.

Signature Recognition

An IDS method that looks for recognizable characteristics and requires regular updates.

Anomaly Detection

An IDS method that identifies abnormal behavior, such as excessive activity, by knowing what normal looks like.

Statistical Detection

An IDS method that detects attacks taking place over a long period of time.

Host-based IDS (HIDS)

An active IDS that blocks traffic, notifies the user, and may monitor log files or file integrity.

File integrity checking

The use of System Integrity Verifiers to check files against hashes to detect unauthorized changes.

Squid Proxy Server

An internet proxy server and cache service used to increase network speed and provide anonymity.

Access Control Lists (OS Based)

File and service permissions, such as Linux rwxrwxrwx and Windows Read/Write/Modify, that define user actions.

Access Control Lists (Network Devices Based)

A white or black list, such as MAC address whitelists or web blacklists, that controls device attachment to a network.

Vulnerability Scanner

A software package, such as nMap or Nessus, that scans computers and networks for known vulnerabilities and outdated software.

Incident Response

The process of identifying, isolating, and investigating a security event.

Disaster Recovery

Activities involving disaster avoidance and restoring full functionality after an event.

Network Forensics

The investigation of network data to determine who, what, when, where, why, and how an event occurred.

Password Hardness Formula

The calculation where hardness $H$ is related to the character set $C$ and length $L$, expressed as H ext{ is } inom{Brute}{Force} ext{ based on } C^L.

Cryptography

Derived from the term "hidden writing," it is the use of secret keys to encode and decode messages.

Caesar Cipher

A classic encryption method using a shift of 3 (e.g., Caesar becomes Fdhvdu).

PAIN

An acronym for the four core goals of cryptography: Privacy, Authentication, Integrity, and Non-repudiation.

Symmetric Encryption

An algorithm class where the same secret key is used for both encryption and decryption.

Asymmetric Encryption

An algorithm class using a public/private key pair to solve key sharing and non-repudiation problems.

Hashing Algorithms

One-way algorithms used to ensure message integrity; common examples include MD5.

Frequency Analysis

A method used to attack substitution ciphers by analyzing the commonality of characters like the letter E.

Transposition Cipher

An encryption method that changes the position of characters rather than substituting them.

Stream Ciphers

A type of symmetric encryption that often utilizes XOR operations on a flow of data.

Block Ciphers

Symmetric encryption that rearranges subkeys and processes data in fixed-size blocks.

Digital Signatures

A hash that has been encrypted with the sender’s private key to provide authentication and non-repudiation.

Cryptosystems

Systems that use all three classes of algorithms (Symmetric, Asymmetric, and Hashing) to ensure PAIN.

Social Engineering

Often called "People Hacking," it is the act of exploiting the human element to compromise a network.

Reverse Social Engineering

Getting a target to seek the attacker out through sabotage, advertising, or assisting while gathering info.

Spear Phishing

A targeted form of phishing, also known as web phishing.

419 Scams

A specific type of phishing scam also known as Nigerian Prince scams.

Obfuscation

The act of obscuring information, such as using Tiny URLs (bit.ly) to mask a link's true destination.

Dumpster diving

A physical control breach involving searching through trash to find sensitive information.

Piggy-backing and Tail-gaiting

Physical security breaches where an unauthorized person follows an authorized person into a restricted area.