COMPUTER SCIENCE - SECURITY - CHAPTER 9 / 1.4 (SECURITY (ENCRYPTION (A…
COMPUTER SCIENCE - SECURITY - CHAPTER 9 / 1.4
Data is valuable. It loses its value if it is lost, accidentally changed or corrupted. For example a doctor is less likely to be able to treat a patient correctly if the data about the patient is not accurate.
Computer security is the protection of computer systems and their data.
PREVENTION AGAINST ACCIDENTAL DATA LOSS OR CHANGE
Data can be lost accidentally through human error, theft, damage to equipment, power failure, hardware failure or misplacing portable media.
Backups and verification help protect against accidental data loss. A backup is a copy of data, kept away from the computer system that can be transferred back to the computer system. Can be made automatically and manually.
We can back up data onto various types of storage media such as: magnetic media, optical media and cloud storage (online).
A bank might backup several times a day due to the importance and number of the financial transactions that take place while a home school may make a backup of records once a week.
Verification is a check which asks the user to confirm whether or not they wish to go ahead with an action, prevents mistakes happening in the first place. Users may still confirm an action without realising its consequences till later, such as deleting a file, so they are not foolproof.
Asked in situations such as: when deleting files; when attempting to save a file with the same name as an existing file; or when copying older versions of a file into a folder with newer versions of that file.
An unauthorised attempt to access a computer is also known as an attack. As well as physical attacks, where the user has physical access to a computer, attacks can be made through the use of malware, phishing, pharming and Denial of Service or DoS.
Malware is software that is designed to affect the normal operations of a computer. Malware comes in the form of viruses, worms, Trojan horses or spyware. Each form of malware can cause data loss or provide unauthorised access to data. Downloaded from email attachments, USB / RAM sticks and websites.
Viruses - self-replicating software designed to disrupt normal operations of a computer, can cause data loss by deleting or corrupting files.
Worms - programs that do not delete or corrupt files. Instead they replicate themselves over and over filling a computers storage. Can cause a computer to run slow or stop running all together.
Trojan horses - programs that disguise themselves as other programs. When they run they act like any other virus, deleting and corrupting files.
Spyware - programs that collect personal and sensitive data, then send it to the spyware's author.
Phishing directs the user to a fake websites where they may inadvertently give away personal data. Based off the idea of accessing data by simply asking for it. Attempting to gain something by using bait. Designed to gain data like bank account details or username and passwords.
Usually comes in the form of emails that look genuine but contain hyperlinks to fake websites.
A technique which uses emails to trick users into giving away personal information. When a user tries to enter a real website they are instead redirected to a fake website where the user may enter personal data like user IDs and passwords.
Malware installed on a users device looks for domain names for reputable sites and translates them into a different IP address to fake websites.
DENIAL OF SERVICE (DoS) ATTACKS
Attempt to prevent the access of data. A computer is used to overload a server with requests by sending it more than requests than it can handle, its response time slows and prevents it from providing a service.
Server - a computer which handles requests from other computers. Websites and networks are accessed through servers.
Request - a communication which asks for data to be transferred.
Distributed Denial of Service (DDoS) - is where two or more computers attack a server or at the same time.
Usually the attacking computer is infected with malware that instructs the computer to continually send requests to find a server.
Prevents physical access to a computer or local access to a system and data. Cannot help recover lost data.
Locks allow only authorised users to access the computer if its in a locked room. Organisations with sensitive and private data keep their computers with data and backups locked away.
CCTV cameras monitor who physically accesses a system. Deters unauthorised users trying to enter a system
Security guards deter those who do not have permission to access a computer, they can also stop physical access if it is tried when unauthorised, used when data is especially sensitive and important.
Security that prevents access to a computer even if the user has physical access. Also stops unauthorised users gaining access remotely like over the internet.
Most common forms are passwords and User IDs.
Some users make guessing easy by choosing a password associated with themselves like: their date of birth; their initials; name of family member or pet; or favourite item, hobby or place. These are weak passwords. Also should not be used for multiple systems.
Strong passwords are difficult to guess. They are considered strong if: it has at least 8 letters; does not contain complete words or words associated with themselves; uses a mixture of different characters; and if it is different from their last password.
Identifies users by there physical characteristics like their fingerprint, voice patterns, face shapes and iris patterns. Alternative to authentication. Improving but far from perfect so authentication is still mostly used.
Fingerprint scanners scan the users finger and if it matches the authorised users original scan they allow access. Does this by comparing the series of ridges and bumps that make up our fingerprints. Not suitable for children as their patterns change with growth but fairly cheap and reliable.
Voice recognition asks a user to speak a phrase and if they are the same as the information stored access is granted. Fairly reliable but can be difficult in noisy environments, can also fail if user has a cold or soar throat.
Facial recognition takes a picture of a users face and compares it to its records. Checks features such as: the nose, the eyes, the cheek bones, and the distances between them. Reliable but can fail in poor lighting and can fall with changes to hairstyle and glasses.
Iris scanners require the user to place their eye to a scanner that checks its previously made user records. Looks at high resolution detailed images of the iris patterns. Highly reliable but expensive and can be uncomfortable for some users.
Software which finds and removes viruses from a computer by scanning it. Uses a list of viruses and how they work and scans the computer for this malware, if it detects any it removes it or blocks its access to the computer. Constantly updated in order to remain effective as new viruses are made all the time.
A system that protects unauthorised access to or from a computer or network such as: spyware transmitting personal data back to its owner; or DoS malware sending requests. Effective but unauthorised access can still happen as users can modify the rules.
Operate by monitoring traffic in and out with different rules like: only certain programs can send and receive traffic; and access to certain websites or servers can be blocked.
Hardware firewalls protect a network, contained in many routers, while software firewalls protect individual computers and have to be installed to each computer on a network.
An intermediary server that prevents direct access to the server itself. Sits between the main server and the internet. Directs traffic away from the network server so it can check if the request is valid, then the data is retrieved from the network server and sent to the requesting computer so so attacks hit only the proxy server.
Also contain copies of data, but not sensitive data so: if data is lost the original data is still safe; Network is more free to handle requests from computers, speeding up internal access time as a proxy server can transfer data; holds copies of frequently visited webpages so some downloads do not happen over the internet.
Prevent users on a network accessing certain sites, used by many schools. Organisations with large amounts of requests use several proxy servers to help spread the load and speed up response times.
A technique that disguises the content of a message using a key or a way of modifying data to make it difficult to understand if intercepted.
Key - information that describes how a message is encrypted or decrypted.
Caesar cipher - offseting each letter in the alphabet by a certain number of positions
keys are created from numbers generated by using binary digits, The number of binary digits is known as the key length, the longer the key the more possible combinations there are so the harder it is to decrypt.
Symmetric encryption is encrypted and decrypted with the same key while asymmetric encryption is encrypted and decrypted with two different keys that only work in correspondence with the other. The first asymmetric key is public and the second is private so it is harder to brake.
Asymmetric encryption is widely used by organisations like banks and online shops. For banks the users browser decrypts and encrypts the message using the public key while only the bank can decrypt and encrypt the messages with the private key. They are trusted as only the bank can send messages with the private encryption.
A set of rules that handle communications between computers.
Hyper Text Transfer Protocol (HTTP) governs communications across the internet.
Hyper Text Transfer Protocol Secure (HTTPS) is a more secure version of HTTP, often used to handle financial transactions.
File Transfer Protocol (FTP) governs the transfer of files across the internet.
Simple Mail Transfer Protocol (SMTP) handles email communication.
Transfer Control Protocol / Internet Protocol (TCP / IP) handles communications on a network.
Voice over Internet Protocol (VoIP) handles audio / visual communication.
HTTPS makes use of another protocol: Secure Socket Layer (SSL), a protocol that creates a secure encrypted link between one computer and another. Used for online secure transactions of sensitive data like: credit card transactions; transfer of files; web based emails, cloud based storage systems; and virtual private networks.
Transport Layer Security (TLS) - An updated, more secure version of SSL.