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Cipher Decoding - Intermediate-Advanced Level: key-based decoding INTERMEDIATE-ADVANCED

This fundamentals focus worksheet contains 20 intermediate-advanced-level cipher decoding problems. Worksheet 21 of 30 focuses on key-based decoding. Practice cipher algorithms, secret codes, military codes with our step-by-step solutions. Difficulty: advanced concepts with increasing complexity. Recommended for advanced developing learners.

📝 Worksheet 21 of 30 • 20 questions • ⏱️ Estimated time: 20 minutes • 🎯 Intermediate-advanced level

What you'll learn in this worksheet:
Your progress through Cipher Decoding
Worksheet 21 of 30 (70% complete)

Question 1

Using ROT13 cipher, decode: 'SPECIES'
ROT13 (shift 13): SPECIES → FCRPVRF
rot13, rotation

Question 2

Using Vigenère cipher with keyword 'PLAYFAIR', encode: 'ENCRYPT'
Vigenère: ENCRYPT with key 'PLAYFAIR' → TYCPDPB
vigenere, polyalphabetic

Question 3

Using reverse cipher (writing backwards), decode: 'NIAHCKCOLB'
Reverse cipher: NIAHCKCOLB reversed is BLOCKCHAIN
reverse, backwards

Question 4

If 'BRONZE' is encoded as 'KAXWIN' using Caesar cipher, what is the shift value?
Caesar cipher: BRONZE → KAXWIN. Shift = 9
caesar, shift

Question 5

Using Autokey cipher with initial key 'KEY', encode: 'VARIABLE'
Autokey cipher: VARIABLE with key 'KEY' → FEPDASTE
autokey, vigenere

Question 6

Using Vigenère cipher with keyword 'KEY', decode the ciphertext: 'PMPO'
Vigenère: With key 'KEY', PMPO → FIRE
vigenere, polyalphabetic

Question 7

Using Baconian cipher (5-bit binary encoding), decode: '01100 00100 10010 10010 00000 00110 00100'
Baconian decoding: 01100 00100 10010 10010 00000 00110 00100 → MESSAGE
baconian, binary

Question 8

If 'ROBOT' is encoded as 'NKXKP' using Caesar cipher, what is the shift value?
Caesar cipher: ROBOT → NKXKP. Shift = 22
caesar, shift

Question 9

Using reverse cipher (writing backwards), decode: 'LEVON'
Reverse cipher: LEVON reversed is NOVEL
reverse, backwards

Question 10

Decode the hexadecimal string: '48454C4C4F'
Hex decoding: 48454C4C4F → HELLO
base64, hex, encoding

Question 11

Using keyboard shift cipher (shift right on QWERTY), encode: 'LEADERSHIP'
Keyboard shift (right): LEADERSHIP → ARSFRTDJOQ
keyboard, qwerty

Question 12

Using ROT13 cipher, decode: 'MEMORY'
ROT13 (shift 13): MEMORY → ZRZBEL
rot13, rotation

Question 13

Using reverse cipher (writing backwards), decode: 'ECAEP'
Reverse cipher: ECAEP reversed is PEACE
reverse, backwards

Question 14

Using Columnar Transposition cipher with key 'LOCK', encode: 'DESERT'
Columnar Transposition with key 'LOCK': DESERT → SEDRET
transposition, columnar

Question 15

Using Atbash cipher (A↔Z, B↔Y, C↔X...), decode: 'INDUSTRIAL'
Atbash: INDUSTRIAL → RMWFHGIRZO
atbash, mirror

Question 16

Using keyword cipher with keyword 'CAESAR', decode: 'SRCTF'
Cipher alphabet: CAESRBDFGHIJKLMNOPQTUVWXYZ
Decoding SRCTF → DEATH
keyword, substitution

Question 17

Using Vigenère cipher with keyword 'SPYWARE', decode the ciphertext: 'KTANEK'
Vigenère: With key 'SPYWARE', KTANEK → SECRET
vigenere, polyalphabetic

Question 18

Using keyword cipher with keyword 'GRAY', decode: 'EBP'
Cipher alphabet: GRAYBCDEFHIJKLMNOPQSTUVWXZ
Decoding EBP → HER
keyword, substitution

Question 19

Using Autokey cipher with initial key 'ENIGMA', encode: 'ACCOUNTING'
Autokey cipher: ACCOUNTING with key 'ENIGMA' → EPKUGNTKPU
autokey, vigenere

Question 20

Using keyword cipher with keyword 'PERL', decode: 'RMPST'
Cipher alphabet: PERLABCDFGHIJKMNOQSTUVWXYZ
Decoding RMPST → COAST
keyword, substitution
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