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Stream ciphers & ChaCha20-Poly1305
The same module told visually, ready to present. Speaker notes carry the full explanation.
Symmetric
Stream ciphers & ChaCha20-Poly1305
A keystream instead of fixed blocks, and AES-GCM's fastest rival
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Two kinds of cipher
Block ciphers versus stream ciphers
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The core equation
Ciphertext = plaintext xor keystream
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Inside ChaCha20
Building the keystream with ARX
No table lookups, so no cache-timing leaks
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Authenticated encryption
Poly1305 makes it an AEAD
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In the wild
Where ChaCha20-Poly1305 runs
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The one rule
Never reuse a key and nonce
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