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Computer Network
A group of two or more computers that are linked together.
World Wide Web (WWW)
Internet application of interlinked web pages based on the HTTP protocol.
Client
Computer or software application that requests services from a server located on the internet eg., a Web browser is an example of a client.
Server
A host that provides some kind of service eg., Google's Gmail Service.
Computing System
A group of computing devices and programs working together for a common purpose.
Protocol
A system of rules that govern the behavior of some system.
SMTP (Simple Mail Transfer Protocol) and POP (Post Office Protocol)
Sets of rules that govern the email services.
URI (Uniform Resource Identifier)
WWW identifier that uniquely identifies a resource on the WWW.
Digital Divide
Gap between those who have access to the internet and computers and those who do not, usually affected by socioeconomic, geographic, or demographic characteristics.
Ethernet
Network that uses wires to connect computers.
Bandwidth
The rate at which data is downloaded or uploaded in a network.
Latency
A measure of the time it takes for a piece of data to reach its destination.
Modem
A device that connects a computer to an Internet Service Provider (ISP).
LAN (Local Area Network)
Network that connects computers within a school or home.
WAN (Wide Area Network)
Network that connects devices over a broad geographic region -- e.g., a telephone network.
HTTP (HyperText Transfer Protocol)
The set of rules that governs the WWW application.
HTML (HyperText Markup Language)
A language for formatting Web pages.
Routing
The process of finding a path from sender to receiver.
Internet Service Provider (ISP)
A company that provides customers with Internet access.
Wifi
A network that uses radio waves to connect devices (computers, smart phones, printers).
Host
A computer that's connected directly to the Internet, often a computer that provides certain services or resources.
Ping
A networking utility used by network administrators to test the reachability of a host on the Internet.
Traceroute
A networking utility used to trace the route and measure delays of packets moving through the Internet.
Packet
A collection of data used by the TCP/IP protocol to transmit data across the Internet.
Packet Switching
The method by which information is transmitted through the Internet.
Fault-Tolerant
The capability of a system to continue operating properly in the event of the failure of one or more of its components.
Abstraction Layer
The Internet is organized into several of these layers that are controlled by various protocols.
Scalability
The capacity for the system to change in size to meet new demands.
Router
A device that transmits data between two different networks.
IP Address
A unique string of numbers separated by periods that identifies each computer using the Internet Protocol to communicate over a network.
IPv4
IP version 4 is an older 32 bit IP address.
IPv6
IP version 6 is a newer 128 bit IP address which allows for many more devices to be addressed.
Domain Name
A hierarchical name (such as trincoll.edu) that identifies a domain and an institution on the Internet.
DNS (Domain Name System)
An Internet service that translates domain names into IP addresses.
Cryptography
Means, literally, 'secret writing'.
Encryption
The process of using a secret key to convert plaintext into ciphertext.
Function
A procedure that computes and returns a value.
Local Variables
Variables that are declared and exist only inside a procedure or function.
Cipher
A system for creating secret messages.
Plaintext
The unencrypted, readable message.
Ciphertext
An unreadable, secret message.
Decryption
The process of using a secret key to convert ciphertext into plaintext.
Encryption Key
A piece of secret data used in by encryption and decryption algorithms.
Encryption Algorithm
Algorithm that uses a secret key to encrypt messages.
Symmetric Encryption
An encryption system where the same key is used for both encryption and decryption.
Substitution Cipher
A cipher where the letters from a ciphertext alphabet are substituted for the letters in a plaintext message in a systematic way.
Transposition Cipher
A cipher where the letters in the plaintext are rearranged without substitution.
Brute Force Attack
In cryptography, this attempts to try every possible encryption key to break a secret message.
Frequency Analysis
Counts the occurrence of the letters in an encrypted message in an effort to discover patterns that might reveal the encryption key.
Polyalphabetic Substitution
A system where multiple alphabets are used to encrypt a single message.
One Time Pad
An example of perfect (unbreakable) encryption, which is achieved by using, only once, a random polyalphabetic key that is as long as the message itself.
Symmetric Cipher
A cipher in which a single key is used for both encryption and decryption.
Asymmetric Cipher
A cipher in which separate but related keys are used for encryption and decryption.
Key Exchange Problem
The problem of sharing a secret cryptographic key between Alice and Bob without Eve being able to intercept it.
Public Key Cryptography
A cryptographic system that uses two keys -- a public key known to everyone and a private or secret key known only to the recipient of the message.
Diffie-Hellman
An algorithm used to establish a shared secret between two parties.
RSA (Rivest-Shamir-Adleman)
A cryptosystem for public-key encryption, and is widely used for securing sensitive data, particularly when being sent over an insecure network such as the Internet.
HTTPS
A protocol for secure (trusted, encrypted) communication over the Internet.
SSL (Secure Socket Layer)
A protocol for establishing an encrypted link between a web server and a browser.
Certificate Authority (CA)
An entity that issues digital certificates.
Digital Certificate
A data packet that certifies the holder of a public key.
Trust Model
The use of a trusted third party to verify the trustworthiness of a digital certificate.
Intractable
A computational problem is intractable if the only known way to solve the problem depends on an exponential algorithm.
Debugging
The process of removing errors from computer hardware or software.
Computer Bug
Informal term for error in computer hardware or software, term coined by Grace Hopper.
Syntax Error
Error that results from a violation of the programming language grammatical rules.
Logic/Semantic Error
Error in which the program is not working as it is designed to work.
Run-Time Error
Mistake in the program that occurs during the execution of a program.
Strong Password
Password that is easy for a user to remember but would be difficult for someone else to guess based on knowledge of that user.
Multi-Factor Authentication (MFA)
Users are asked to present several separate pieces of evidence involving knowledge, possession, and/or inherence.
Biometrics
Using unique physical characteristics such as fingerprints, face recognition, etc, for identification.
Malware
Software intended to damage a computing system or to take partial control over its operation.
Virus
Malicious program that can copy itself and gain access to a computer in an unauthorized way.
Ransomware
Malware that encrypts and locks computer systems until a ransom is paid.
Phishing
Technique that is used to trick a user into providing personal information usually through email.
Keylogger
Program to record every keystroke made by a computer user.
Rogue Access Point
Wireless access point that gives unauthorized access to secure networks.
Firewalls
Barriers that protect a network from unauthorized access.
Crowdsourcing
The practice of obtaining input or information from a large number of people via the Internet.
