Poly1305
/ˌpɒliˈwʌn-θɜːrtiː-fʌɪv/
n. “A tiny guardian watching every bit.”
Poly1305 is a cryptographic message authentication code (MAC) algorithm created by Daniel J. Bernstein, designed to verify the integrity and authenticity of a message. Unlike encryption algorithms that hide the content, Poly1305 ensures that data has not been tampered with, acting as a digital seal that can detect even a single-bit change in a message.