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Learn about the benefits and drawbacks of virtualization, as well as about cloud storage and virtual clients. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification. 3.2 - Virtualisation Exam Board: OCR Specification: 2016 - Unit 1 What is virtualisation? Virtualisation is the creation of a virtual version of a device , software , operating system or server . These virtual versions can then be run on a different physical computer system , such as a powerful server . There are many different types of virtualisation . Storage virtualisation combines multiple separate storage devices into acting and appearing like a single , central storage system . Using storage virtualisation improves scalability as further devices can join the storage system if more space is required . It also simplifies the management of storage across the network. Server virtualisation allows one physical server to be divided into and host multiple virtual servers , each running separately . Each virtual server operates independently , handling its own operating system and applications . This allows for resources to be used more effectively and improves the scalability and versatility of the physical server . Client Virtualisation (Virtual Clients) Client virtualisation is when several virtual desktops are run on a single server - think back to the hypervisor from 3.1 . A virtual client is a full desktop environment where the processing happens remotely . For example, where an operating system is managed and hosted centrally but displayed locally on a different computer. These are often known as 'dumb clients ' because the server does the processing for it , meaning it can have minimal resources like a slow processor and little memory / storage . General Benefits & Drawbacks of Virtualisation Benefits of virtualisation: Costs are cheaper in the long-term because money is saved by not purchasing multiple physical devices . Money is also saved due to less cabling and lower power consumption . If set up efficiently, it can be used for higher performance at a lower cost - "Do more with less" . Programs can be tested in a secure environment before main-system deployment. Simplified response to recover after a disaster because only the server needs to be fixed. Drawbacks of virtualisation: If not set up efficiently, users could face serious performance issues , as fewer servers do more work. If a single physical system fails , the impact will be greater . Initial set up is complex , requires technical knowledge and can cost a lot. Easier for hackers to take more information at once as the data is stored in the same place. Benefits of client virtualisation: All data is stored in one central location , making backup and disaster planning easier to manage . The whole system can be managed , secured and updated from the server , rather than from each individual system. Hardware costs will be reduced because the virtual clients do not store or process their own data , meaning they can be of a low spec . Users can have multiple virtual machines and log in remotely (from anywhere with internet access ). Drawbacks of client virtualisation: Users will be unable to work if network connectivity is lost . There is a high strain on the server as the virtual clients do not store or process data themselves . An increased load on the server might result in poor performance for each client, especially with multiple connections . As the data is stored in one location , there are security risks of unauthorised access if the server is not adequately protected . Server Virtual Clients Cloud Technology 'The cloud ' is storage that is accessed through a network , primarily the internet. A cloud server is an example of storage virtualisation as data may be stored across multiple physical devices . There are three different types of cloud storage: Private cloud is where a business will have its own data centre that employees can access. This allows for flexible and convenient data storage and gives the business control over data management and security . Users of the private cloud will not usually have to pay individually for access - but the company will need to spend a lot of money on set up and maintenance . Public cloud uses third-party service providers such as Google Drive or DropBox to provide storage over the internet . Public cloud is usually a pay-for-use service , where businesses will pay for specific amounts that they need. Data management and data security is maintained by the cloud provider and the business is dependent on them providing constant access and deploying effective security measures. Hybrid cloud uses a mix of on-site storage (private cloud) and third-party (public cloud) services . Organisations can move workloads between private and public clouds as their specific needs and costs change . A benefit of hybrid cloud is that it gives an organisation greater flexibility and data storage options. As an example, a company could use on-site or private cloud storage to hold sensitive information and third-party, public cloud services to hold less important data . Q uesto's Q uestions 3.2 - Virtualisation: 1. What is the difference between server and storage virtualisation ? [ 2 ] 2a. What is a virtual client ? [ 1 ] 2b. What are the advantages and disadvantages of client virtualisation ? [ 8 ] 3. Explain any further general advantages and disadvantages of using virtualisation , not covered in your answer to 2b. [4 ] 4. Describe the differences between private , public and hybrid cloud storage. [6 ] 3.1 - Server Types Topic List 3.3 - Network Characteristics

Learn about algorithms including programming principles, variables and sequencing. Based on the 2020 Eduqas (WJEC) GCSE specification. 8.1: Programming Principles Exam Board: Eduqas / WJEC Specification: 2020 + Problem Solving There are four stages to computational thinking (smart problem solving ). Decomposition is when you break a problem down into smaller tasks so that it is easier to solve . Pattern Recognition is the process of identifying similar patterns within a problem . Abstraction is when you ignore unnecessary information and focus only on the important facts . Algorithms are the final stage as step-by-step rules are created to solve the problem . An algorithm is usually written as psuedocode or presented as a flowchart . Programming Constructs There are three constructs (ideas) of programming that most programs will contain: Sequence Structuring code into a logical, sequential order . Selection Decision making using if statements . Iteration Repeating code , often using for loops or while loops . Variables Large programs are often modular - split into subroutines with each subroutine having a dedicated purpose. Local variables are declared within a specific subroutine and can only be used within that subroutine . Global variables can be used at any point within the whole program . Local variable advantages Saves memory - only uses memory when that local variable is needed - global variables use memory whether they are used or not. Easier to debug local variables as they can only be changed within one subroutine. You can reuse subroutines with local variables in other programs. Global variable advantages Variables can be used anywhere in the whole program (and in multiple subroutines). Makes maintenance easier as they are only declared once. Can be used for constants - values that remain the same. Local & Global Variables Constants A variable is data that can change in value as a program is being run. A constant is data that does not change in value as the program is run - it is fixed and remains the same. An example of a constant in maths programs is pi - it will constantly remain at 3.14159 and never change. π π Counts & Rogue Values When using iteration (looping) the loop must eventually be able to stop. A count is a variable that is used to record the current iteration (loop number). A rogue value is an unexpected value that will cause the loop to end . For example by typing "Stop" into a loop that asks for numbers. Self-documenting Identifiers An efficient program will use variables with sensible names that immediately state their purpose in the program. Using variable names like 'TotalNum' and 'Profit' rather than 'num1' and 'num2' mean that other programmers will be able to work out the purpose of the code without the need for extensive comments. Q uesto's Q uestions 8.1 - Programming Principles: Problem Solving 1. What is meant by 'decomposition '? Why is it important ? [2 ] 2. What does the term 'abstraction ' mean? Why is it important ? [2 ] 3. What is pattern recognition ? [2 ] 4a. What is an algorithm ? [1 ] 4b. What are the two ways of writing an algorithm ? [2 ] Programming Constructs 1. Describe and draw a diagram for the 3 programming constructs . [6 ] Variables 1. What is the difference between local and global variables ? [4 ] 2. Describe two advantages of using local variables . [2 ] 3. Describe two advantages of using global variables . [2 ] 4. What is a constant ? Give an example . [2 ] 5. Why is it important to use self-documenting identifiers when programming? [2 ] 6. What is a count ? What is a rogue value ? [2 ] 7.1 - Language Levels Theory Topics 8.2 - Understanding Algorithms

Learn about malware such as viruses, worms, trojans, spyware, keyloggers and ransomware. Also, learn about phishing, data theft, interception and cyber attacks including SQL injection, IP address spoofing, DDoS attacks and brute force. Based on the 2020 Eduqas (WJEC) GCSE specification. 3.8: Cyber Threats Exam Board: Eduqas / WJEC Specification: 2020 + 3.8a: Malware What is malware? Malware is any type of harmful program that seeks to damage or gain unauthorised access to your computer system. Virus A virus can replicate itself and spread from system to system by attaching itself to infected files . A virus is only activated when opened by a human . Once activated, a virus can change data or corrupt a system so that it stops working . Worm A worm can replicate itself and spread from system to system by finding weaknesses in software . A worm does not need an infected file or human interaction to spread. A worm can spread very quickly across a network once it has infiltrated it. Trojan A trojan is a harmful program that looks like legitimate software so users are tricked into installing it . A trojan secretly gives the attacker backdoor access to the system . Trojans do not self replicate or infect other files. Spyware Spyware secretly records the activities of a user on a computer. The main aim of spyware is to record usernames, passwords and credit card information . All recorded information is secretly passed back to the attacker to use. Keylogger A keylogger secretly records the key presses of a user on a computer. Data is stored or sent back to the attacker. The main aim of a keylogger is to record usernames, passwords and credit card information . Keyloggers can be downloaded or plugged into the USB port . Ransomware Ransomware locks files on a computer system using encryption so that a user can no longer access them. The attacker demands money from the victim to decrypt (unlock) the data . ? ? ? ? Attackers usually use digital currencies like bitcoin which makes it hard to trace them. 3.8b: Data Theft Phishing Phishing is the method of misleading individuals or organisations into sharing sensitive information (such as passwords or bank details ), often through the use of emails . Phishers may pose as a trusted company like Amazon or YouTube to direct users to open malicious attachments or encourage them to follow fraudulent links to steal their data . Social Engineering Social engineering means to trick others into revealing their personal data by posing as a trusted source . For example, impersonating an IT technician of a school via email and asking for a student's username and password . Interception This is when data packets on a network are intercepted by a third party (e.g. a hacker) and copied to a different location than the intended destination. Software called packet sniffers are used to intercept and analyse data packets. Physical Theft Computer systems (e.g. laptops) or storage devices (e.g. USB stick) may be stolen in public or from offices. Unwanted systems and storage media should be disposed of securely as data could be stolen from discarded information , such as old CDs or even printed paper. 3.8c: Online Threats & Attacks Hacking Hacking is the method of exploiting weaknesses in a system or network to create, view, modify or delete files without permission. A hacker is anyone who gains access to data or systems that they do not have authority to access. DoS Attack A DoS (Denial of Service ) attack is when a computer repeatedly sends requests to a server to overload the system . A server overload will slow the system and may take websites offline temporarily. A DDoS (Distributed Denial of Service ) attack is a coordinated attack using a botnet of infected systems to overload a server with requests . A botnet is a large group of devices controlled and used maliciously by an attacker. SQL Injection SQL ( Structured Query Language ) is a programming language used for manipulating data in databases . A SQL injection is when a malicious SQL query (command) is entered into a data input box on a website. If the website is insecure then the SQL query can trick the website into giving unauthorised access to the website’s database . An SQL injection can be used to view and edit the contents of a database or even gain administrator privileges . ' or 1 = 1 Brute Force Attack In order to break a password , every possible combination is tested in order from start to finish . This is not a quick method but it should break the password eventually and can be sped up if multiple computer systems are used at the same time. IP Address Spoofing An attacker changes the IP address of a legitimate host so any visitors to the URL are instead taken to a spoofed ( fake ) web page . This web page is used to record any inputted data (such as usernames and passwords) and send it back to the attacker . The spoofed web page can also be used to install malware . Q uesto's Q uestions 3.8 - Cyber Threats: 3.8a - Malware: 1. What is malware ? [ 2 ] 2a. Describe three characteristics of a virus . [3 ] 2b. Describe three characteristics of a worm . [3 ] 2c. What is a trojan ? [ 3 ] 2d. Describe how spyware and keyloggers work. [ 4 ] 2e. Explain how ransomware works and why it is difficult to trace attackers . [ 3 ] 2f. In your opinion, which malware do you think is the most dangerous and why ? [ 2 ] 3.8b - Data Theft: 1. Describe what is meant by ' phishing ' . [ 2 ] 2. Give an example of social engineering . [ 2 ] 3. What is interception ? What software is used to intercept data packets? [ 2 ] 4. Describe why systems and storage media should be disposed of securely . [ 1 ] 3.8c - Online Threats & Attacks: 1. Describe what is meant by ' hacking ' . [ 2 ] 2a. Describe what a DoS attack is and its impact . [2 ] 2b. Describe how a DDoS attack is different to a DoS attack . [2 ] 3. Describe what an SQL injection is and how an attacker would use it. [ 4 ] 4. Describe what is meant by a brute force attack . [ 2 ] 5. Describe IP address spoofing and its purpose . [ 3 ] 3.7 - The Internet Theory Topics 3.9 - Protection Against Threats

Learn about each of the 8 stages of data analysis including exactly what should occur at every stage. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 3.4 - Stages of Data Analysis Exam Board: OCR Specification: 2016 - Unit 2 Data analysis is the process of identifying and collecting data to be viewed and modelled, in the aim of discovering patterns or trends that can be used for conclusions and decision-making. 1. Identify the need Before anything else can take place, objectives are set for what the data analysis will hope to achieve. Aims must be clear and well defined . For example, an organisation should define what information will be needed and what exactly they want to find out by the end of the process (the purpose of the data analysis). Not clearly defining the required information or purpose could lead to worthless results and a waste of the entire data analysis process. 2. Define the scope In this stage the restrictions of the project are defined. Scope includes factors such as budget , content , detail , timescales (deadlines) and any further constraints . 3. Identify potential sources Project planners must identify a wide range of sources for the potential information, ensuring that it is unbiased and covers the objectives . The specific data will depend on the project but it could include sales figures or customer surveys for example. 4. Source and select information Information is gathered from the identified sources in stage three. Any unsuitable data is excluded so that results are not unreliable as poor quality information can lead to numerous negative consequences . Planners will have to determine the accuracy and reliability of any identified sources and select the best . 5. Select the most appropriate tools There are many different data analysis tools that can be used as part of this sequence; in this stage the most appropriate tool for the project is selected. Examples include methods of presentation such as charts and graphs for a visual representation of data . Regression analysis can also be used - regression is the determining of relationships e.g. if the amount spent on advertising bottled water increases, will consumption increase too or are other factors involved? If there is a link, a business can continue to spend more on advertising if consumption and profit also rises. Trend analysis is another option - this shows patterns over time , for example, bottled water consumption each year over the past decade. 6. Process and analyse data Data has now been collected and can be inputted into software such as spreadsheets or databases to further analyse. Putting collected data into a spreadsheet for example allows for analysis to begin as graphs can be created from the data and any patterns or trends discovered. 7. Record and store information The data has been collected and analysed and now any findings are written into a report . Any patterns, trends or findings can be described with statistical evidence generated from the analysis. 8. Share results A report is worthless if not shared with the stakeholders . Sharing can take different forms such as a typed document posted out to stakeholders, an email with major findings summarised or as a post on a website . Q uesto's Q uestions 3.4 - Stages of Data Analysis: 1. List the 8 stages of data analysis in order. [8 ] 2. A supermarket chain called 'Fresh Food UK' wants to complete data analysis to see which stores across the country have been most profitable in the last year . Explain how Fresh Food UK would use each of the 8 stages of data analysis . [16 ] 3.2 & 3.3 - Information Categories Topic List 3.5 - Data Analysis Tools

Learn about methods of physically protecting data such as biometric devices, RFID and tokens, privacy screens and shredding. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification. 5.4 - Physical Security Exam Board: OCR Specification: 2016 - Unit 1 RFID & Tokens Radio-frequency identification (RFID) uses electromagnetic fields to attach tags to physical objects . RFID tags can be embedded within 'dumb' objects such as clothing, packages and even animals. RFID is used with security tokens (such as an ID keycard ) to permit the access of authorised people to certain areas. RFID can be used by IT companies to track equipment and manage access . Shredding This is the cutting up of documents (paper or CDs ) into small pieces so that they cannot be reassembled and read. Sensitive data on paper or optical disc should be shredded when no longer required. Locks A lock can be used to prevent access to server rooms or sensitive data stores . Only authorised personnel with the right key will have access. Physical Security Measures Biometrics Biometric devices require the input of a human characteristic (such a fingerprint , iris or voice scan ). The biometric data is checked against previously inputted data in a database . A match will allow access to the user. See more in section 1.1 . Privacy Screens These plastic screens are placed over a monitor to obscure the screen to anyone except the person sitting directly in front of them. This prevents shoulder surfing and prevents data from being read by unauthorised people nearby. Q uesto's Q uestions 5.4 - Physical Security: 1. Explain how locks can be used as a physical security method within an organisation. [2 ] 2. Explain what RFID is and how it can be used with tokens as a physical security method. [3 ] 3. Explain how biometric devices can be used as a physical security method. [3 ] 4. Explain how privacy screens are used to protect data. [2 ] 5. What is the purpose of shredding ? [2 ] 5.3 - Threats Topic List 5.5 - Digital Security

The homepage for all content aimed at Key Stage 3 students studying Computer Science / IT including computer hardware, Python, App Inventor 2 and Cyber Security. Key Stage 3 Topics These topics are aimed at Year 7 - 9 students (11 - 14 year olds) studying computing. Hardware The Motherboard The CPU Memory Expansion Cards Python Basics 1. The Basics 2. Variables 3. Inputs 4. Calculations 5. Selection 6. Turtle 7. Link to GCSE Python Cyber Security Malware Phishing & Staying Safe Other Topics Desktop Publishing

Learn how to edit code in Greenfoot to make objects move randomly across the screen. This can be used on 'enemy' objects. Part 3 of the Greenfoot Tutorial for the Eduqas / WJEC GCSE 2016 specification. 3. Random Movement 1. Code for Random Movement Greenfoot Tutorial Watch on YouTube: Right-click on your enemy class on the main screen and select ' Open editor '. The enemy character should always be moving, so start with move(1); Next we will use an if statement to start the random movement. This code generates 10 random numbers and if it is less than 1 then it will run the proceeding code. If we don't do this, the character will turn too much or too little . This code generates a random angle between 0 and 90. The - 45 part is necessary otherwise the character will always move to the right . See the diagram below for an explanation: 2. Bounce at World Edge You may have noticed that the enemy objects can get 'stuck' in the corners or when they hit the edge of the world. In the act() method, below the random movement code , add the code in the red box . This code checks to see if the object is at the edge , and turns it around ( 180 degrees ) if it is. 3. Compile and Run Click the Compile button at the top of the code editor . Then you can go back to the main Greenfoot window and click Run to test if your enemy objects move . Click on me if you've got an error that you're stuck with. < Part 2 - Movement with the Arrow Keys Part 4 - Remove Objects >

Learn how to use App Inventor 2 to create simple programs. Try to complete tasks 4, 5 and 6 on this page. Perfect for Key Stage 3 students to experiment with block coding, objects and properties. App Inventor Tasks 4, 5 & 6 - Using Variables This page will teach you how to make three simple apps that use variables . These apps will prepare you for the final program - the Pop-up Blob game. App #4 - Button Masher The first app to make is a simple program that counts how many times a button is pressed (but don't press it too much! ) This app will introduce you to using variables in App Inventor. Open App Inventor 2 (use the button below) and create a new project. You will need to log in with a Google account. App Inventor 2 Firstly, grab a button and two labels and place them in the Viewer . Using the Properties tab, you need to make the following changes: Button Text to 'Press Me!' Button Height to 60 pixels and Width to 'Fill parent...' Label 1 Text to 'Number of Presses' Label 2 Text to '0' Both Label 1 and Label 2 Width to 'Fill parent...' Both Label 1 and Label 2 TextAlignment to 'centre : 1' In the Components tab change the component names to be easier to code later. Switch to Blocks layout and drag an initialize global to block into the centre. In the blank space type 'Presses' - this is the name of the variable that will store how many times the button has been pressed. Drag a 0 block from Math. This will set the number of presses to 0 when the app starts. Drag a when ButtonPresses Clicked from the ButtonPresses section and add the necessary code inside. This code increases the variable value of Presses by 1 every time the button is clicked. It also changes the LabelPresses text to display the number of presses. Improve Your App As you will have seen in the video at the top, I programmed the app to go a bit crazy when 35 presses were recorded. In the code below I have shown how to use an if then block to check if the number of presses is 35. If it is then I have made the button invisible - this is an important feature we will use in later programs. Copy this code and add the following features to the then part of the if statement: Set the background colour to black. Change the Label1 Text Colour to white. Change the Label1 Text Size to 40. Change the Label1 Text to 'You broke it...' Program 4 Complete! App #5 - Timer The second app to make is a timer that counts up one second at a time. It also needs a reset button that sets the timer back to 0 again. It will introduce you to the clock component and enabling / disabling components. Open App Inventor 2 (use the button below) and create a new project. You will need to log in with a Google account. App Inventor 2 The code for this program is straightforward; it will take more effort getting the layout right. In the Palette tab, drag a HorizontalArrangement from the Layout section. It will look like an empty grey box at first. Grab a Button as well and place it underneath. Now drag two labels into the grey box and place the second one directly after the first, it may take a few attempts to get them to appear side by side like below: The last component to drag over is Clock (it is in the Sensors section in the Palette tab). It will go into its own section underneath: Change the name of some of the components so that they make more sense. Now to make some changes in the Properties tab. You should know enough by now to work out how to change your components so that it looks like this in your Viewer : Change your layout to Blocks and add the code blocks to the right. This code makes the Label named Seconds update by 1 every second, just like a timer. The code to the left will make the Label named Seconds reset to 0 when the button is pressed. Improve Your App As you will have seen in the video at the top of this task, I added a pause/unpause button that will set the enabled feature of the timer to true or false. You will need to complete the following steps (I've been deliberately vague to make it a challenge - break it down into small steps and use the colours to help you): Add a new button. Add code that, when the new button is clicked , checks if the TimerEnabled is true . If it is, then change TimerEnabled to false . Else change it to true . Now you also need to change the Text of the Button to read either "Pause" or "Unpause" . Program 5 Complete! App #6 - Windy Day The third app to make is an app that blows leaves around your screen. It will introduce you to random numbers, the canvas and coordinates . Open App Inventor 2 (use the button below) and create a new project. You will need to log in with a Google account. App Inventor 2 In the Palette tab, drag a Canvas from the Drawing and Animation section. A Canvas allows sprites (objects) to move around inside of it. In Properties , change the Height and Width of Canvas to 'Fill parent...' for both, so it fills the whole screen. In the Palette tab, drag over five ImageSprites from the Drawing and Animation section and drop them anywhere inside the canvas. Download the leaf picture with all App Inventor images on the basics page here . Upload the leaf image it in the Media tab. In the Components tab change the names of your ImageSprites to be leaf1, leaf 2 etc. For each leaf sprite, in the Properties tab, change the Picture to the leaf you just uploaded and change Height and Width to 30 pixels each. Finally, in the Palette tab, in the Sensors section, drag over a Clock . Your Viewer should look like the image to the left. X axis Y axis 0 300 500 Now for an explanation of coordinates. Each sprite (leaf) has an x coordinate (horizontal) and a y coordinate (vertical). For example, the leaf in the top right would have coordinates of x = 270 and y = 100. Can you work out approximately what the other leaves coordinates would be? What the code blocks below do is randomise the x and y coordinates for leaf1 every second. The word integer means a whole number . Use this code and add to it to make all 5 leaves randomly change coordinates. Improve Your App Add a pause / unpause button, just like in the Timer app that pauses the timer so that the leaves stop blowing (and starts them blowing around again too). Find a nice picture (maybe of a park?) online and upload it in the Media tab. Set this as the Canvas BackgroundImage . Add an audio file of some whooshing (why not record it yourself?). Program 6 Complete! Task 7 KS3 Home

Learn about common prevention methods of minimising cyber security risks including anti0malware, firewalls and penetration testing. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). 4.2: Preventing Vulnerabilities Exam Board: OCR Specification: J277 Watch on YouTube : Preventing Vulnerabilities Penetration Tests Penetration tests are carried out as part of ethical hacking. The purpose of a penetration test is to review the system's security to find any risks or weaknesses and to fix them . Internal tests are to see how much damage could be done by somebody within the company with a registered account. External tests are for white hat hackers to try and infiltrate a system from outside the company . Anti-Malware Software Anti-malware software is used to locate and delete malware, like viruses, on a computer system. The software scans each file on the computer and compares it against a database of known malware . Files with similar features to malware in the database are identified and deleted . There are thousands of known malware, but new forms are created each day by attackers, so anti-malware software must be regularly updated to keep systems secure. Other roles of anti-malware software: Checking all incoming and outgoing emails and their attachments . Checking files as they are downloaded . Scanning the hard drive for viruses and deleting them . Firewall A firewall manages incoming and outgoing network traffic . Each data packet is processed to check whether it should be given access to the network by examining the source and destination address . Unexpected data packets will be filtered out and not accepted to the network. Other roles of a firewall include: Blocking access to insecure / malicious web sites . Blocking certain programs from accessing the internet . Blocking unexpected / unauthorised downloads . Preventing specific users on a network accessing certain files . Secure Passwords ******** Usernames must be matched with a secure password to minimise the chances of unauthorised users accessing a system. Passwords should contain a mix of uppercase and lowercase letters , punctuation and numbers . Passwords should be of a substantial length (at least 8 characters) and should be regularly changed . User Access Levels Access levels are used to only allow certain users to access and edit particular files. ' Read-Only ' access is when a user can only view a file and is not allowed to change any data . For example, a teacher might set homework instructions as read-only for students to view. ' Read and Write ' access allows a user to read and edit the data in a file. For example, a teacher might set an online workbook as read and write access for students to fill in. It is important to set access levels so that only authorised users can view and change data. The more users who have access to a file, the more likely it is to be compromised. Certain users may also have no access to a file - when they can't view or edit it. Encryption Encryption is the process of scrambling data into an unreadable format so that attackers cannot understand it if intercepted during transmission. The original data (known as plaintext ) is converted to scrambled ciphertext using an encryption key . Only at the correct destination will the encryption key be used to convert the ciphertext back into plaintext to be understood by the receiving computer. Physical Security A lock can be used to prevent access to server rooms or locations that store confidential data . Only authorised personnel with a matching key will have access. Biometric devices require the input of a human characteristic (such a fingerprint , iris or voice ). The biometric data is checked against previously inputted data in a database. Only a match will allow access to the user. Other forms of physical security include keycards , security staff , CCTV cameras and alarms . Q uesto's Q uestions 4.2 - Preventing Vulnerabilities: 1. Describe the purpose of penetration tests . [2 ] 2. Describe the purpose of anti-malware software and its different roles . [ 4 ] 3. Describe the purpose of a firewall and its different roles . [ 4 ] 4. State three rules for choosing a strong password . [ 3 ] 5. Describe the three types of access level . [6 ] 6a. Describe the purpose of encryption . [ 2 ] 6b. Explain how encryption works, using the terms plaintext , key and ciphertext . [ 4 ] 4.1 - Security Threats Theory Topics 5.1 - Operating Systems

Learn about the methods of digital protection including antimalware, firewalls and obfuscation. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 6.6 - Logical Protection Exam Board: OCR Specification: 2016 - Unit 2 Logical protection refers to using digital methods of security to protect computer systems and data. Usernames & Passwords ****** Anti-Malware Usernames must be matched with a secure password to minimise the chances of unauthorised users accessing a system. Passwords should contain a mix of uppercase and lowercase letters , punctuation and numbers . Passwords should be of a substantial length (at least 8 characters) and should be regularly changed . Anti-virus software scans a system and removes viruses . If left to infect a system a virus could delete data or permit access to unauthorised users . Anti-spyware software removes spyware on an infected system so hackers cannot view personal data or monitor users. Organisations should install and regularly update anti-virus and anti-spyware programs. Firewall Encryption Firewalls prevent unauthorised access to or from a network . Firewalls filter data packets and block anything that is identified as harmful to the computer system or network. Firewalls can also be used to block access to specific websites and programs. A firewall can be in the form of a physical device which is connected to the network, or software installed on a computer system. Encryption is the conversion of data ( plaintext ) into an unreadable format ( ciphertext ) so it cannot be understood if intercepted . Encrypted data can only be understood by an authorised system with a decryption key . There are two types of encryption . Encryption at rest is when data is encrypted while it is being stored on a system or storage drive. Encryption in transit is to secure the data as it being transferred between systems on a network. Tiered Levels of Access Obfuscation ?????? The purpose of tiered levels of access is to grant different types of permission to certain users. Managing levels of file access ensures that only authorised people can access and change certain files . There are different levels of file access : No access Read-only - Allows a user to view but not edit. Read/write - Allows a user to view and edit. Obfuscation is when data is deliberately changed to be unreadable to humans but still understandable by computers . Program code might be obfuscated to stop rival programmers from viewing and stealing it if they were able to access it. Specialist software can be used to obfuscate data and convert it back into a human-readable format. Q uesto's Q uestions 6.6 - Logical Protection: 1a. Describe why usernames and strong passwords are necessary. [2 ] 1b. State 3 rules for choosing a strong password . [3 ] 2. Describe the purpose of anti-virus and anti-spyware software. [4 ] 3. Describe the roles of a firewall . [4 ] 4. Explain what encryption is. What are the two types? [4 ] 5. Why would an organisation use tiered levels of access ? What are the 3 levels of file access ? [5 ] 6. What is obfuscation ? State a scenario in which it would be used. [3 ] 6.5 - Physical Protection Topic List

Learn about how to convert between the denary (decimal), binary and hexadecimal number systems. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). Exam Board: OCR 2.4a: Number Systems Specification: J277 Watch on YouTube : Binary and Denary Hexadecimal Number System Ranges Binary to Denary Denary to Binary Binary to Hexadecimal Hexadecimal to Binary Denary to Hexadecimal Hexadecimal to Denary What is binary? By now you should know that computer systems process data and communicate entirely in binary . Topic 2.3 explained different binary storage units such as bits (a single 0 or 1), nibbles (4 bits) and bytes (8 bits). Binary is a base 2 number system. This means that it only has 2 possible values - 0 or 1 . What is denary? Denary (also known as decimal ) is the number system that you've been using since primary school. Denary is a base 10 number system. This means that it has 10 possible values - 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 . Binary & Denary Convert from binary to denary: Convert from denary to binary: Hexadecimal What is hexadecimal? Hexadecimal is a base 16 number system. This means that it has 16 possible values - 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E and F . Hexadecimal is used as a shorthand for binary because it uses fewer characters to write the same value . This makes hexadecimal less prone to errors when reading or writing it , compared to binary. For example, 100111101011 in binary is 9EB in hexadecimal. Hexadecimal only uses single-character values. Double-digit numbers are converted into letters - use the table on the right to help you understand. Binary to hexadecimal: Hexadecimal to binary: Converting from denary to hexadecimal / hexadecimal to denary To convert from denary to hexadecimal or from hexadecimal to denary , it is easiest to convert to binary first . However, it is possible to convert directly from denary to hexadecimal or directly from hexadecimal to denary . The videos below explain both methods . Denary to hexadecimal: Hexadecimal to denary: Watch on YouTube Watch on YouTube Watch on YouTube Watch on YouTube Watch on YouTube Watch on YouTube Q uesto's Q uestions 2.4a - Number Systems: 1. Explain why hexadecimal numbers are used as an alternative to binary . Use an example . [ 3 ] 2. Convert the following values from binary to denary : a. 00101010 b. 11011011 c. 01011101 d. 11101110 e. 01011111 [1 each ] 3. Convert the following values from denary to binary : a. 35 b. 79 c. 101 d. 203 e. 250 [1 each ] 4. Convert the following values from binary to hexadecimal : a. 11110101 b. 01100111 c. 10111010 d. 10010000 e. 11101001 [1 each ] 5. Convert the following values from hexadecimal to binary : a. C2 b. 8A c. DE d. 54 e. F7 [1 each ] 6. Convert the following values from denary to hexadecimal : a. 134 b. 201 c. 57 d. 224 e. 101 [1 each ] 7. Convert the following values from hexadecimal to denary : a. 32 b. A5 c. 88 d. C0 e. BE [1 each ] Click the banners below to try self-marking quizzes (Google Forms) on these topics. Binary to Denary: Denary to Binary: Binary to Hexadecimal: Hexadecimal to Binary: 2.3 - Data Units Theory Topics 2.4b - Binary Addition & Shifts

Learn how to use mathematical operators in Python. Try practice tasks and learn through text and images. Perfect for students learning GCSE Computer Science in UK schools. top Python 4b - Mathematical Operators Modulo Division The modulo operator - the percentage symbol % - will work out the remainder left over when one value is divided by another. print (30 % 6) = 0 30 ÷ 6 = 5, which is a whole number, so there is no remainder and 0 is output . print (30 % 7) = 2 30 ÷ 7 = 4 remainder 2 ; so the remainder is output . You can use modulo with variables too: num1 = 33 num2 = 4 print ( "The remainder is" , num1 % num2) The remainder is 1 = A common use of modulo is to check if a number is odd or even . If a number has no remainder when divided by 2 then it is even . = num = int ( input ( "Enter a number: " )) if num % 2 == 0: print (num, "is even." ) else : print (num , "is odd." ) Enter a number: 400 400 is even. Enter a number: 191 191 is odd. = Modulo Div i sion Task 1 ( Remainder) Ask the user to input a whole number . Use the modulo operator ( % ) to check if there is a remainder when the user's number is divided by 5 . Print the re mainder. Example solution: Enter a number: 123 The remainder when divided by 5 is 3 Modulo Div i sion Task 2 ( Rollercoaster) Use the odd/even program above to help solve this problem: A rollercoaster only lets people on in groups of 4 . Ask the user to input a number for how many people are in their group. Check if that number is directly divisible by 4 using modulo division ( % ). If it is then print “Perfect groups of four!” Else print “You will be split up” . Example solutions: Welcome to the Hyper Coaster! How many in your group? 6 You will be split up! Welcome to the Hyper Coaster! How many in your group? 12 Perfect groups of four! Integer Division Integer division removes any decimal numbers when performing division , leaving just the integer (whole number ). In Python integer division is performed using // . print (20 / 3) print (20 // 3) = 6.666666666666667 6 Integer Div i sion Task 1 ( Integer Division by 5 ) Use an input line with int to ask the user to enter a number . Use integer division ( // ) to divide the number by 5 without keeping any decimal values . Challenge: Improve your solution by altering the print line to be more user friendly . Example solutions: Enter a number: 27 5 Enter a number: 27 5 goes into 27 5 times. Integer Div i sion Task 2 ( Plane Rows) A large plane has 6 seats in each row. Input the number of passengers on the plane and use integer division to work out how many full rows will be filled. Example solution: How many passengers are there in total? 174 There will be 29 full rows on the plane. Exponent (Powers) An exponent is the number of times a value is multiplied by itself , for example 2 = 2 x 2 x 2 = 8 . The symbol to represent an exponent in Python is ** . For example: 4**2 represents 4 which is also 4 x 4 . 3 2 print (4**4) = 256 base = 5 exponent = 4 print (base**exponent) 625 = Exponent Task 1 ( Square Number) Use an input line with int to ask the user to enter a number . Output the square of this number. Example solution: Enter a number: 12 12 squared is 144 Exponent Task 2 ( Custom Exponent) Use an input line with int to ask the user to enter a number, this will be the base . Make another input line with int to ask for the exponent . Use ** between the base and the exponent and print it. Challenge: Make your solution better by including the base and exponent in the print line. Example solutions: Enter the base: 7 Enter the exponent: 3 343 Enter the base: 7 Enter the exponent: 3 7 to the power of 3 is 343 ⬅ 4a - If Statements 4 c - Log ical Operators ➡