Cryptography

Hashing

Integrity, not secrecy.

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150 XP
What Is a Hash?
One-way, deterministic, avalanche.
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150 XP
Collision Resistance
The birthday paradox, and why N bits only buys N/2 security.
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150 XP
The SHA Family
SHA-1 (broken), SHA-2, SHA-3.
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150 XP
HMAC
Integrity + authenticity with a shared key.
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200 XP
Merkle Trees
Prove one leaf in O(log N) without shipping the whole set.
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200 XP
BLAKE2 & BLAKE3
Why modern hashes are faster than SHA-256 — and just as safe.
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200 XP
Content Addressing
Git, IPFS, and the 'address by content not name' mental model.
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220 XP
Sponge Construction (SHA-3)
Absorb, squeeze, and why SHA-3 doesn't have SHA-2's length-extension flaw.
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200 XP
Bloom Filters
Probabilistic membership — tunable false positives, never false negatives.
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