Computer Science - 4CP0 PearsonEdexcel

Encryption

Gbogbo ọrọ náà

Every online payment, private message and password submission travels across networks that the sender does not own and cannot fully control. Without protection, anyone able to intercept that traffic could read it in plain sight. Encryption is the tool that turns readable data into something meaningless to everyone except the intended recipient, and it has been reinvented many times over more than two thousand years.

In this lesson you will learn why data needs to be encrypted before it travels across a network, and you will work through four classic ciphers named on the specification: the Caesar, Vigenere and Rail Fence ciphers, which you will apply by hand, and the Pigpen cipher, whose 'key' is a set of secret symbols rather than letters.

Ebumnobi

Understand the need for data encryption
Understand how encryption algorithms work (Pigpen cipher, Caesar cipher, Vigenere cipher, Rail Fence cipher)

Maapụ uche

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Kaadị ncheta

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Akwụkwọ Ọmụmụ

Data sent across a network, whether the open internet, a public Wi-Fi hotspot or a company's internal network, passes through equipment that is not under the sender's or receiver's control: routers, switches and cables owned by third parties. Anyone with access to that equipment, or running software that captures network traffic, can potentially read every packet that is not protected.

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Nnyocha Ọmụmụ

Ekele diri gi maka imecha ihe karịrị na Encryption. Ugbu a na ị na-enyochakwa isi echiche na echiche ndị dị mkpa, ọ bụ oge iji nwalee ihe ị ma. Ngwa a na-enye ụdị ajụjụ ọmụmụ dị iche iche emebere iji kwado nghọta gị wee nyere gị aka ịmata otú ị ghọtara ihe ndị a kụziri.

Ị ga-ahụ ngwakọta nke ụdị ajụjụ dị iche iche, gụnyere ajụjụ chọrọ ịhọrọ otu n’ime ọtụtụ azịza, ajụjụ chọrọ mkpirisi azịza, na ajụjụ ede ede. A na-arụpụta ajụjụ ọ bụla nke ọma iji nwalee akụkụ dị iche iche nke ihe ọmụma gị na nkà nke ịtụgharị uche.

Jiri akụkụ a nke nyocha ka ohere iji kụziere ihe ị matara banyere isiokwu ahụ ma chọpụta ebe ọ bụla ị nwere ike ịchọ ọmụmụ ihe ọzọ. Ekwela ka nsogbu ọ bụla ị na-eche ihu mee ka ị daa mba; kama, lee ha anya dị ka ohere maka ịzụlite onwe gị na imeziwanye.

What is the term for the original, readable data before it is encrypted? A) Ciphertext B) Key C) Plaintext D) Hash Answer: C
A Caesar cipher uses a shift of 4. What does the plaintext letter 'A' become? A) B B) D C) E D) Z Answer: C
Which cipher uses a repeating keyword to vary the shift applied to each letter? A) Caesar cipher B) Rail Fence cipher C) Vigenere cipher D) Pigpen cipher Answer: C
Which type of cipher rearranges the order of letters without changing the letters themselves? A) Substitution cipher B) Transposition cipher C) Symmetric cipher D) Monoalphabetic cipher Answer: B
Why is data encrypted before being sent across a public network? A) To make the file smaller B) To speed up transmission C) To stop the data being read if it is intercepted D) To correct transmission errors Answer: C

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