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Poly1305

As explained in Real-World Cryptography

Poly1305 is a message authentication code that authenticates data using polynomial arithmetic modulo a fixed constant and a one-time authentication key.

Poly1305 is a message authentication code: it helps detect changed data by processing input with polynomial arithmetic and a one-time authentication key. In ChaCha20-Poly1305, it authenticates both ciphertext and associated data. section 4.5.3

Inside ChaCha20-Poly1305

ChaCha20 encrypts the plaintext and derives the keys required by Poly1305; Poly1305 then authenticates the ciphertext and associated data.

How Real-World Cryptography covers it

How deep it goes
Explains block-by-block absorption, the accumulator, authentication key r, random value s, and tag formation, without giving implementation details.
Examples
Uses an accumulator, authentication keys r and s, ciphertext, associated data, and the ChaCha20-Poly1305 construction.
What you can do after
Evaluate how Poly1305 contributes authentication when paired with ChaCha20 in an authenticated-encryption construction.
How it connects
Connects message authentication codes with ChaCha20, authenticated encryption, ciphertext, associated data, and authentication tags.
Cover of Real-World Cryptography
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Related concepts

This explainer was generated by Manning's knowledge graph from the text of Real-World Cryptography. The section links point to the parts of the book it draws on.