Cryptography

Public Key

The key exchange miracle.

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250 XP
Toy RSA Cracker
Factor n. Recover d. Decrypt the flag.
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150 XP
Key Generation
Entropy, key sizes, and why a single bad RNG breaks everything.
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120 XP
Public vs Private
Encrypt with public, decrypt with private. Sign with private, verify with public.
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170 XP
Elliptic Curves
secp256k1, P-256, Ed25519 — same security as RSA at a fraction of the size.
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170 XP
Diffie-Hellman
Two parties, one shared secret, zero transmissions of it.
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170 XP
Digital Signatures
RSA-PSS, ECDSA, Ed25519 — and why the PS3 master key was recovered.
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170 XP
Key Management
Storage, rotation, HSMs, KMSes, agents — the systems that wrap the keys.
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180 XP
Post-Quantum
Shor's algorithm, NIST PQC, Kyber, Dilithium, hybrid TLS.
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160 XP
PGP vs Modern Tools
Why PGP is broken in practice, and the modern primitives that replaced it.
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