IGCSE Computer Science Paper 1 Word Scramble: 2.2 Methods of Error Detection and 2.3 Encryption (Modules 189–203)
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Word scramble
Unscramble the letters and write each key term on the line.
1
NOOHCISG A ODHTME
Decide if the error happens in transmission or data entry, pick the check that fits, then justify it by what it can and cannot detect.
2
PTIEOCIRNNTE
When someone copies data as it travels across a network through routers and other devices, so unprotected data can be read by anyone who intercepts it, for example on public Wi-Fi.
3
XTANPTIEL
The original, readable data (text, file, image or message) before it is encrypted. Decrypting ciphertext with the correct key turns it back into ______.
4
EPTTIHEXRC
The scrambled, unreadable data made when plaintext is encrypted. It is what gets sent across a network and looks meaningless without the key.
5
REINTCYOPN YKE
A secret value used by the encryption algorithm to scramble data into ciphertext and unscramble it again. A different key gives different ciphertext, and a longer key is harder to guess.
6
ECIMRSTYM CTONPYRNEI
The sender encrypts plaintext into ciphertext with a key; the receiver decrypts it back to plaintext using the same key. A wrong key gives unreadable output.
7
HESDRA CESTRE EYK
In symmetric encryption, the receiver can only decrypt if they hold the same key as the sender, so the key must be shared before any data is sent.
8
YEK RETNIIPNOETC
If an attacker intercepts a symmetric key while it is being shared, they can decrypt every message that uses that key, so the encryption is defeated.
9
BUIPCL YKE
The half of a key pair that the owner shares openly. Anyone can use it to encrypt data sent to the owner, but it cannot decrypt that data. Only the matching private key can.
Answer Key
IGCSE Computer Science Paper 1 · Modules 189–203
1NOOHCISG A ODHTME → Choosing a method — Decide if the error happens in transmission or data entry, pick the check that fits, then justify it by what it can and cannot detect.
2PTIEOCIRNNTE → interception — When someone copies data as it travels across a network through routers and other devices, so unprotected data can be read by anyone who intercepts it, for example on public Wi-Fi.
3XTANPTIEL → plaintext — The original, readable data (text, file, image or message) before it is encrypted. Decrypting ciphertext with the correct key turns it back into plaintext.
4EPTTIHEXRC → ciphertext — The scrambled, unreadable data made when plaintext is encrypted. It is what gets sent across a network and looks meaningless without the key.
5REINTCYOPN YKE → encryption key — A secret value used by the encryption algorithm to scramble data into ciphertext and unscramble it again. A different key gives different ciphertext, and a longer key is harder to guess.
6ECIMRSTYM CTONPYRNEI → symmetric encryption — The sender encrypts plaintext into ciphertext with a key; the receiver decrypts it back to plaintext using the same key. A wrong key gives unreadable output.
7HESDRA CESTRE EYK → shared secret key — In symmetric encryption, the receiver can only decrypt if they hold the same key as the sender, so the key must be shared before any data is sent.
8YEK RETNIIPNOETC → key interception — If an attacker intercepts a symmetric key while it is being shared, they can decrypt every message that uses that key, so the encryption is defeated.
9BUIPCL YKE → public key — The half of a key pair that the owner shares openly. Anyone can use it to encrypt data sent to the owner, but it cannot decrypt that data. Only the matching private key can.