Foundations of Computer Science Final

Foundations of Computer Science Final Leave the first rating Students also studied Terms in this set (220) Science Computer Science Computer Security and Reliability Save WGU Foundations of Computer Scie...70 terms Michai_Staten67 Preview Foundations of Computer Science 37 terms elayna_kempPreview WGU D429 - Key Terms 270 terms aleaner-in-tech Preview COMPU 72 terms ash plaintextordinary text ciphertext"unreadable" encrypted text encryptionplaintext to ciphertext decryptionciphertext to plaintext cipheran algorithm used to encrypt and decrypt text keya set of particular parameters that guide the cipher algorithm

• big types of ciphers1. Substitution cipher
• Transposition cipher

Substitution cipherreplacing one character with another not very secure b/c easy to break by figuring out "e" then "the" etc Caesar ciphertype of substitution cipher used between Caesar and his generals done by shifting a certain number of positions up/down the alphabet spaces can be omitted or represented by character(s) punctuation could be included easy to crack Transposition cipherrearranging the order of existing characters easy to crack but not as easy as substitution ciphers

route cipherencryption = characters laid out in grid and then moved into a string of letters by following a particular route around the grid decryption = string of letters written on grid via the reversal of the route and then read cryptanalysisthe process of "breaking" an encryption figuring out the plaintext without knowing the cipher or key FBI issuesthey've tried/are trying (idk) to force citizens to hand over deciphering keys they also want "back door" access to certain secure sites which poses a risk to the information on those sites as they would then be easier to hack Turingfather of computers worked for Britain's code-breaking center during WWII, he was a key player in breaking the German military's code (known as Enigma) public-key cryptography(idk if this is aka RSA or if RSA is an example)

• mathematically related public and private keys

most secure bc extremely difficult to decrypt RSA algorithm definitionan asymmetric code created with a trapdoor function which makes it easy to encrypt messages but difficult to decrypt them RSA private keyc^d mod n = m coprime2+ numbers that share no factors other than 1 totientΦ created by Euler Φ(n) would be all the numbers less than n which are also coprime (with n, I think...idk if it means coprime with each other) { I wrote if n > 7, Φ = usually prime - 1, but ifk what I meant } modulo operationthe quotient left over in a closed number system ex: time = on a closed system of 12 hour cycles, it's 10 AM and I want to know what time it'll be in 4 hours 10 + 4 = 14 ==> 14/12 has a remainder of 2 so it'll be 2 o'clock; 14 mod 12 = 2 home network IP addressesusually begin with 192.168.spoofingmaking it look like something came from some other device ARPANet encryptiondidn't exist b/c it was only used by a small number of military branches and educational institutions so why would they need encryption Navajoused in written messages in the US military during wwii as a way of sending messages without encryption computer networka collection of computing devices connected to share info + resources

wirelessconnected via radio waves to a wireless access point (which is at least one node in the network which allows others to access one another wirelessly) node/hostany device in the network bandwidthspeed; data transfer rate w/in network protocolrules for how data is formatted and processed client/server modelclient requests, server responds file servercomputer than stores + maintains files for the network Web servercomputer that responds to requests for Web pages for the network P2P modelpeer-to-peer model decentralized servers that share resources + responsibilities LANlocal-area network small # of nodes in a close geographical area

• basic topologies we talked about1. linear/bus
• ring
• star
• fully/completely connected

robustreliable linear/bus networka-b-c-d # of wires = n - 1 least expensive least robust slowest speed ring networka-b-c-d-a # of wires = n little more expensive little more robust little more fast star networka-b, a-c, a-d, a-e # of wires = n - 1 decent improvement over ring network for expense, robustness, and speed fully/completely connected networkeveryone directly connected to everyone else most expensive more robust highest speed # of wires = (n)(n-1) / 2

ethernetuses linear/bus topology industry standard for LANs WANwide-area network 2+ LANs connected gatewaythe node which communicates between its LAN and the others in the WAN Internetglobal WAN MANmetropolitan-area network developed for large areas/cities

example: college campus

Internet backbonethe set of networks carrying Internet traffic ISPInternet service provider

• types of ways ISPs route Internet connections 1. phone modem

2. DSL

• cable modem

phone modem connectionsconvert computer data into analog audio signals which are transferred via phone lines

S L O W

DSLdigital subscriber line uses phone lines BUT transfers a data via digital signals so it's much quicker phone modems and DSLs can be used on the same lines at the same time b/c they use different frequencies cable modumtransfers network data via cable lines broadbandnetwork which generally provide bandwidth greater than 256 Kbps packeta unit of data packet-switchingpackets are sent individually and reassembled at destination; multiple potential alternative routes for packets to take to arrive at destination Engelbartdude who invented the mouse routera node which directs a packet between networks towards its final destination repeaterstrengthens + propagates signal over long distances proprietary systemsprivate technologies for businesses