Cryptographymedium250 pts0 solves
Reused Pad
Two messages were XOR-encrypted with the same key stream. You know the first message — it is the standard banner: "ACCESS GRANTED :: Welcome to the CyberSecurity.pk training range. Keep this session private and do not share the key with anyone." Recover the second.
Learning objectives
Understand why a one-time pad must never be reused and perform a known-plaintext attack on XOR.
Instructions
Use ciphertexts.txt (hex). The flag appears in the second plaintext.
Prerequisites: XOR operation; a short Python script helps.
Flag format:
cspk{...}Files: ciphertexts.txt (0.4 KB) (download after registering)
Useful tools: CyberChef
References
Write-up
The full write-up and learning takeaways unlock after you solve this challenge — spoilers stay hidden until then.