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AES and ChaCha
A technical deep dive into how the ChaCha20 cipher is taking on AES as the gold standard for symmetric encryption, and a lesson about the power of simplicity in cryptographic design.
A full understanding of this operation involves finite-field arithmetic, which is beyond the scope of this blog — but worth exploring if you're curious about how AES achieves both performance and cryptographic strength at such a low level. ChaCha20, derived from it's predecessor Salsa, is a stream cipher that is designed as pseudorandom function that uses a combination of Add, Rotate and XOR operations, commonly referred to as ARX. By measuring how long AES takes to encrypt different inputs, an attacker can statistically infer which parts of the lookup tables were accessed—and by extension, reconstruct portions of the secret key.
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