Introduction to ICT - PDF

Introduction to ICT FEB11013(X) Paul Bouman Kim Schouten ICT Information and Communications Technology Information Systems store, collect, process and control information. Communication Systems transport information between locations. Technology enables newe...

Introduction to ICT FEB11013(X) Paul Bouman Kim Schouten ICT Information and Communications Technology Information Systems store, collect, process and control information. Communication Systems transport information between locations. Technology enables newer and better applications. Information Systems Systems that deal with data, usually computers. Early example include: the abacus (2400 B.C.) cog-wheel based devices sliding rules for logarithms IBM’s early punch-card machines Most important device is the general purpose computer: Instructions Processing Unit Information Information Systems Systems that deal with data, usually computers. Early example include: the abacus (2400 B.C.) cog-wheel based devices sliding rules for logarithms IBM’s early punch-card machines Most important device is the general purpose computer: Software Hardware Data General ICT Knowledge We will cover the following topics today: Files and Data Communication Systems and the Internet Authentication and Encryption Collaboration and the Cloud Files and Data Bits and Bytes We will only focus on digital data. The smallest unit of digital data is a bit, which models two possibilities (0 or 1) A group of 8 bits is called a byte and models 28 = 256 possibilities. Fun trick: using your fingers as bits, you can count to 31 with one hand! Link: https://www.youtube.com/watch?v=I8V4kVSO5Ns We can use bits to model numbers. Numbers can be used to model characters, colors, measurements, etc. By creating long sequences we can model all kinds of data: Many characters can model a text Many colors can model an image Many measuremenets of air movenents can model sound Files We usually organize bits and bytes in files. Files have a number of properties: File size (number of bytes) File name (usually a descriptive name of the contents) File extension (part of the name indicating what is stored) Files can be organized in folders or directories. Archive files (such as.zip files) can contain multiple files. Useful for transporting many files Also helps to reduce file size via compression Data Processing Software Applications can read, process and write files Some applications can process many types of files. A certain type of file can be processed by different applications. Web Browser HTML files, CSS files, JavaScript files, Image files, Video files, etc. Microsoft Word DOCX files (MS Word), ODT files (OpenDocument), RTF files, etc. Microsoft Excel XLSX files (MS Excel), ODS files (OpenDocument), CSV files, etc. 7-Zip ZIP files, 7z files, etc. Notepad Raw, text-based editing of files Data Formats Although all files store bits and bytes, the structure of formats can be vastly different. An important distinction is between text-based formats and binary formats. Text-based formats are designed in a way that humans can read them. Usually they require more space, but space is cheap nowadays Examples: HTML, CSV, XML. Binary formats are not readable by humans, but can be efficiently processed by computers. They require less space and can be processed a bit faster. Examples: video’s, images, audio, zip-files. Excel’s XLSX and Word’s DOCX files are secretly zip-files containing different types of files. Communication Systems and the Internet Communication Systems For information to be useful, it has to be at right place at the right time. Different systems have been used troughout the ages: Messenger by foot (see Marathon) Smoke signals Carrier pigeons More modern systems introduced faster communication over greater distance Telegraph Telephone Fax The Internet The Internet A network of computer networks Telephone/Fax: direct open line between two endpoints The Internet: short messages routed via many computers in the network The Internet – Packets and the Internet Protocol (IP) Communication over the internet happens via packet-switching Messages are divided in small packets that are send one by one. Every packet follow a different route via different computers A packet has a number of properties The address of the sender The addres of the receiver Some other properties related to time The contents of the packet Addresses are described using IP addresses Most common, but scarce are the IPv4 addresses, e.g. 130.115.158.254 IPv4 works with 32 bit addresses, so 232 possible addresses. Currently moving toward IPv6 addresses, e.g. fe80::c118:3329:ca70:eccc%12 IPv6 works with 128 bit addresses, so 2128 possible addresses. The Internet – Domain Name System (DNS) For the average human, IP addresses are hard to remember For big sites, they may want to rotate machines to serve customers in order to spread out demand over the available capacity The Domain Name System translates names (that we can remember) to addresses. For example: www.eur.nl is a name, that has to be translated into an IP-address before you computer can request information. DNS is controlled by the Internet Coorporation for Assigned Numbers and Names (ICANN) For top-level domains, such as.nl and.amsterdam, seperate parties control the subdomains. In the Netherlands, we have the SIDN for.nl domains. Verisign manages.com and.net. Domain names typically have a yearly registration fee. The Internet - Issues Issue: how do you know you communicate with someone? This is called Authentication Issue: can you trust the computers that transport your messages? You cannot. We can use Encryption to protect sensitive data. Authentication and Encryption Authentication In real life, you can recognize people you met before. Over the phone, this is a lot more difficult. On the internet, this is even more difficult. Authentication is all about checking someones identity Identity theft and fraud are becoming more serious issues in the digital world. Most well known type of authentication: passwords Authentication - Passwords Most systems work with providing a username and password Username is public information, password is private to you Being able to provide the password is evidence that you are the user. Possible risk: passwords may be easy to guess Dictionary attack: test many common passwords and see if one works. Brute force attack: try all possible passwords of a certain length. Solution: use strong passwords, that require an enormous amount of tries. Read https://en.wikipedia.org/wiki/Password_strength Possible risk: password reuse. If your password is guessed on one website, it can be used for other sites. Use different passwords, or use a password manager. Authentication More secure authentication methods exists Two-factor (or multi-factor) authentication. Use multiple proofs of your identity Example: you need both a cashcard and a PIN number Google, Facebook, Dropbox, DigID and others support this First login with your password Second type in a code you were sent via e-mail/phone/app Token based authentication Use a special device to generate a number unique to that device Encryption Encryption relies on a secret key. The key can be used to encrypt or decrypt a message. An encrypted message looks like random, incomprehensible data. You need the correct key to turn it back into something useful. The Advanced Encryption Standard (AES) offers very secure encryption. AES-256 works with keys of 256-bits. Trying all keys would take longer than our life spans, even if Google and the NSA team up. Is approved for encryption of US Government TOP SECRET data. One the internet, AES is typically used to transfer large amounts of data securely. Exchange of AES keys between two parties is a complicated issue. Encryption – Key Exchange and HTTPS On the internet, two parties that want to communicate securely need to exchange keys. Certificates or public keys are pieces of cryptographic information that can be used to verify that the party you communicate with are who they claim to be. Using certificates, a web of trust is built. This is used to verify new keys. Securely ask the people who you trust whether they trust the new certificate. They can ask their trusted partners for information securely as well. As so on… The https protocol uses these certificates to check whether the party you communicate with is trustworthy and encrypt the connect. The http protocol does not and is therefore not suitable to transport sensitive data. The https protocol is just regular http over a Secure Sockets Layer (SSL) Other communication protocols (e.g. e-mail) can be run over SSL as well. Collaboration and the Cloud Collaboration and ICT ICT can be used to collaborate more effectively However, different users typically work on different devices Emailing files back and forth leads to redundancy Advantage: if one device breaks, there are other copies Possible issue: who has the most current version of the work? In certain cases, redundancy is something we desire If we want to archive data, or have backup systems when something breaks In other cases, redudancy is something we want to avoid When collaborating on a document with multiple people we don’t want to end up with multiple versions. Synchronization becomes an important issue. Collaboration and ICT - Centralization For collaboration, we desire centralization A central location where the “true” information is kept. When synchronizing with a central data repository, conflicts can occur Two people modify the same file at the same time You modified a file, but it turned out that someone else sent a new file to the central repository in the meantime. The more frequent synchronization between users and the central repository occurs, the sooner conflict can be detected and resolved. Collaboration and ICT – Application Models Local applications These are applications that run on your local device and interact with data on that device. Regular Microsoft Office applications such as Word and Excel are some examples. Useful if you want to run computations locally and stay independent of other systems. Client-Server applications Tasks and/or responsibilities are divided between a client application that typically runs on your local device, and a server application that typically runs on an external server. Typical examples: web browser (client) and web server, mail client and mail servers, streaming services (servers) for music or video, etc. Has the advantage that data is often centralized automatically on the server. Possible risk: if the server has a problem, the application is not available for any user. Collaboration and ICT – The Cloud The Cloud model provides an alternative to the traditional way ICT is used Move away from owning devices and software licenses to services Infrastructure as a Service (IaaS) Instead of having an IT department that buy and manages hardware and network infrastructure, you rent the capacity you need from a specialize company. Typically deals with basic ICT systems such as hardware, servers, network infrastructure and storage Platform as a Service (PaaS) Offers a platform for developers that provides some standardized services. Example: Facebook applications can rely on Facebook to offer user identification and possibly sales/advertisements, but you can develop applications on top of these. Probably not that relevant for you. Collaboration and ICT – The Cloud Software as a Service (SaaS) Instead of running applications on your own computer, you access them via a website. Advantage: you can use software directly from the webbrowser without any installation. Disadvantage: you completely depend on the software vendor. Famous examples: Google Docs and Office 365 Allow you to work on documents and spreadsheet within your browser Multiple users on different devices can work on the same document Although we will use regular Excel in this course, it is still very useful to be familiar with this. Other examples include Customer Relationship Management (CRM) software, Accounting software, … Allows small to medium sized companies to cut costs of IT-support. Sometimes vendors have data escrow or source code escrow If the software vendor goes bankrupt, a third party inherits the important properties and provides them to the original customers.