POLYVAL is a universal hash function that uses multiplication by a fixed parameter within a Galois field.
It is not a general purpose hash function - The key must be secret, unpredictable and never reused.
POLYVAL is typically used to compute the authentication tag in the AES-GCM-SIV construction.
pub const Polyval = Hash(.little, false)
pub const Polyval = Hash(.little, false)