IGCSE Computer Science Paper 1 Crossword: 2.2 Methods of Error Detection and 2.3 Encryption (Modules 189–203)
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Crossword
Read each clue and write the matching term in the grid. Numbers in brackets show the letters in each word.
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Across
- 1. Encryption cannot stop data being intercepted, but the interceptor sees only ciphertext and cannot get the plaintext ______ the key, so passwords and bank details stay safe. Word 2 of: __________ _______ the key (7)
- 3. 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. Word 1 of: _________ __________ (9)
- 6. In symmetric encryption, the receiver can only decrypt if they hold the same key as the sender, so the key must be ______ before any data is sent. Word 1 of: ______ ______ key (6)
- 8. 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. Word 1 of: ______ key (6)
- 9. The scrambled, unreadable data made when plaintext is encrypted. It is what gets sent across a network and looks meaningless without the key. (10)
- 10. The original, readable data (text, file, image or message) before it is encrypted. Decrypting ciphertext with the correct key turns it back into ______. (9)
Down
- 2. Word 1 of the term in 1 Across: __________ _______ the key (10)
- 4. A secret value used by the ______ algorithm to scramble data into ciphertext and unscramble it again. A different key gives different ciphertext, and a longer key is harder to guess. Word 1 of: __________ key (10)
- 5. 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. Word 1 of: ________ a method (8)
- 7. Word 2 of the term in 6 Across: ______ ______ key (6)
Answer Key
IGCSE Computer Science Paper 1 · Modules 189–203
1W
I
T
H
O
2U
T
N
3S
Y
M
M
4E
T
R
I
5C
N
E
H
C
A
O
6S
H
A
R
E
D
O
7S
Y
A
S
E
8P
U
B
L
I
C
9C
I
P
H
E
R
T
E
X
T
L
N
R
I
E
G
E
O
T
10P
L
A
I
N
T
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X
T
Across
1WITHOUT — Encryption cannot stop data being intercepted, but the interceptor sees only ciphertext and cannot get the plaintext ______ the key, so passwords and bank details stay safe. Word 2 of: __________ _______ the key
3SYMMETRIC — 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. Word 1 of: _________ __________
6SHARED — In symmetric encryption, the receiver can only decrypt if they hold the same key as the sender, so the key must be ______ before any data is sent. Word 1 of: ______ ______ key
8PUBLIC — 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. Word 1 of: ______ key
9CIPHERTEXT — The scrambled, unreadable data made when plaintext is encrypted. It is what gets sent across a network and looks meaningless without the key.
10PLAINTEXT — The original, readable data (text, file, image or message) before it is encrypted. Decrypting ciphertext with the correct key turns it back into ______.
Down
2UNREADABLE — Word 1 of the term in 1 Across: __________ _______ the key
4ENCRYPTION — A secret value used by the ______ algorithm to scramble data into ciphertext and unscramble it again. A different key gives different ciphertext, and a longer key is harder to guess. Word 1 of: __________ key
5CHOOSING — 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. Word 1 of: ________ a method
7SECRET — Word 2 of the term in 6 Across: ______ ______ key