Intermediate Track3 hours
Advanced Cryptanalysis
2 guided sections and curated resources to get you contest-ready.
Lesson Playbook
2 sections1
Common CTF Crypto Mistakes
Most CTF crypto breaks implementations, not primitives.
Look for:
- XOR with repeated key
- ECB mode
- reused IV/nonce
- weak randomness
- RSA parameter mistakes
2
XOR Helper
XOR is reversible and common.
from itertools import cycle
def xor_bytes(data: bytes, key: bytes) -> bytes:
return bytes(d ^ k for d, k in zip(data, cycle(key)))