crylib 0.2.0

a collection of cryptographic functions
Documentation
//! The Poly1305 authenticator.
//!
//! Poly1305 was designed by Daniel J. Bernstein.

use super::ChaCha20Poly1305;
use crate::{
    aead::{IV_SIZE, TAG_SIZE},
    big_int::UBigInt,
    finite_field::{FieldElement, FiniteField},
};

fn clamp(r: &mut [u8; 16]) {
    r[3] &= 0x0f;
    r[7] &= 0x0f;
    r[11] &= 0x0f;
    r[15] &= 0x0f;
    r[4] &= 0xfc;
    r[8] &= 0xfc;
    r[12] &= 0xfc;
}

pub struct Poly1305 {
    r: FieldElement<3, PolyField>,
    s: FieldElement<3, PolyField>,
    accum: FieldElement<3, PolyField>,
}

impl Poly1305 {
    pub fn auth(msg: &[u8], key: &[u8; 32]) -> [u8; 16] {
        Self::new(key).finish_with(msg)
    }

    pub fn new(key: &[u8; ChaCha20Poly1305::KEY_SIZE]) -> Self {
        let mut r = key[..16].try_into().unwrap();
        clamp(&mut r);

        let r: UBigInt<3> = UBigInt::<2>::from_le_bytes(r).resize();
        let r: FieldElement<3, PolyField> = unsafe { FieldElement::new_unchecked(r) };

        let s: UBigInt<3> = UBigInt::<2>::from_le_bytes(key[16..].try_into().unwrap()).resize();
        let s: FieldElement<3, PolyField> = unsafe { FieldElement::new_unchecked(s) };

        let accum: FieldElement<3, PolyField> = FieldElement::ZERO;

        Self { r, s, accum }
    }

    pub fn update(&mut self, msg: &[u8; TAG_SIZE]) {
        let mut as_int: UBigInt<3> = UBigInt::<2>::from_le_bytes(*msg).resize();
        as_int.0[2] = 1;
        // SAFETY: as_int is guaranteed to be less than `PolyField::MODULUS`.
        let as_fe: FieldElement<3, PolyField> = unsafe { FieldElement::new_unchecked(as_int) };
        self.accum.add_assign(&as_fe);
        self.accum.mul_assign(&self.r);
    }

    /// Updates `self` with `msg`, adding padding if necessary.
    pub fn update_with(&mut self, msg: &[u8]) {
        let blocks = msg.chunks_exact(16);
        let remainder = blocks.remainder();
        for block in blocks {
            self.update(block.try_into().unwrap());
        }
        if remainder.len() > 0 {
            let mut last_block = [0; 16];
            last_block[..remainder.len()].copy_from_slice(remainder);
            self.update(&last_block);
        }
    }

    /// Updates `self` with `msg` and finishes.
    pub fn finish_with(mut self, msg: &[u8]) -> [u8; TAG_SIZE] {
        // TODO: use array_chunks once stabilized
        let blocks = msg.chunks_exact(16);
        let remainder = blocks.remainder();
        for block in blocks {
            self.update(block.try_into().unwrap());
        }
        if remainder.len() > 0 {
            let mut last_block = [0; 16];
            last_block[..remainder.len()].copy_from_slice(remainder);

            let mut as_int: UBigInt<3> = UBigInt::<2>::from_le_bytes(last_block).resize();
            as_int.set_byte(remainder.len(), 1);
            // SAFETY: as_int is guaranteed to be less than `PolyField::MODULUS`.
            let as_fe: FieldElement<3, PolyField> = unsafe { FieldElement::new_unchecked(as_int) };
            self.accum.add_assign(&as_fe);
            self.accum.mul_assign(&self.r);
        }
        self.finish()
    }

    pub fn finish(self) -> [u8; TAG_SIZE] {
        let mut accum = self.accum.into_inner();
        accum.add_assign(&self.s);
        accum.resize::<2>().to_le_bytes()
    }
}

pub fn poly1305_key_gen(
    key: &[u8; ChaCha20Poly1305::KEY_SIZE],
    iv: &[u8; IV_SIZE],
) -> [u8; ChaCha20Poly1305::KEY_SIZE] {
    let block = super::chacha20::block(key, iv, 0);
    block[..ChaCha20Poly1305::KEY_SIZE].try_into().unwrap()
}

#[derive(Eq, PartialEq, Clone, Copy, Debug)]
struct PolyField;

// SAFETY: MODULUS is prime.
unsafe impl FiniteField<3> for PolyField {
    const MODULUS: UBigInt<3> = UBigInt([0xfffffffffffffffb, 0xffffffffffffffff, 0x3]);
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn key_gen() {
        let key = [
            0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d,
            0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b,
            0x9c, 0x9d, 0x9e, 0x9f,
        ];
        let nonce = [
            0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
        ];
        let otk = [
            0x8a, 0xd5, 0xa0, 0x8b, 0x90, 0x5f, 0x81, 0xcc, 0x81, 0x50, 0x40, 0x27, 0x4a, 0xb2,
            0x94, 0x71, 0xa8, 0x33, 0xb6, 0x37, 0xe3, 0xfd, 0x0d, 0xa5, 0x08, 0xdb, 0xb8, 0xe2,
            0xfd, 0xd1, 0xa6, 0x46,
        ];
        assert_eq!(poly1305_key_gen(&key, &nonce), otk);

        let key = [0; 32];
        let nonce = [0; 12];
        let otk = [
            0x76, 0xb8, 0xe0, 0xad, 0xa0, 0xf1, 0x3d, 0x90, 0x40, 0x5d, 0x6a, 0xe5, 0x53, 0x86,
            0xbd, 0x28, 0xbd, 0xd2, 0x19, 0xb8, 0xa0, 0x8d, 0xed, 0x1a, 0xa8, 0x36, 0xef, 0xcc,
            0x8b, 0x77, 0x0d, 0xc7,
        ];
        assert_eq!(poly1305_key_gen(&key, &nonce), otk);

        let key = [
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x01,
        ];
        let nonce = [
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02,
        ];
        let otk = [
            0xec, 0xfa, 0x25, 0x4f, 0x84, 0x5f, 0x64, 0x74, 0x73, 0xd3, 0xcb, 0x14, 0x0d, 0xa9,
            0xe8, 0x76, 0x06, 0xcb, 0x33, 0x06, 0x6c, 0x44, 0x7b, 0x87, 0xbc, 0x26, 0x66, 0xdd,
            0xe3, 0xfb, 0xb7, 0x39,
        ];
        assert_eq!(poly1305_key_gen(&key, &nonce), otk);

        let key = [
            0x1c, 0x92, 0x40, 0xa5, 0xeb, 0x55, 0xd3, 0x8a, 0xf3, 0x33, 0x88, 0x86, 0x04, 0xf6,
            0xb5, 0xf0, 0x47, 0x39, 0x17, 0xc1, 0x40, 0x2b, 0x80, 0x09, 0x9d, 0xca, 0x5c, 0xbc,
            0x20, 0x70, 0x75, 0xc0,
        ];
        let nonce = [
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02,
        ];
        let otk = [
            0x96, 0x5e, 0x3b, 0xc6, 0xf9, 0xec, 0x7e, 0xd9, 0x56, 0x08, 0x08, 0xf4, 0xd2, 0x29,
            0xf9, 0x4b, 0x13, 0x7f, 0xf2, 0x75, 0xca, 0x9b, 0x3f, 0xcb, 0xdd, 0x59, 0xde, 0xaa,
            0xd2, 0x33, 0x10, 0xae,
        ];
        assert_eq!(poly1305_key_gen(&key, &nonce), otk);
    }

    #[test]
    fn poly1305() {
        //let otk = [0; 32];
        //let msg = [0; 64];
        //let tag = [0; 16];
        //assert_eq!(Poly1305::auth(&msg, &otk), tag);
        //
        //let otk = [
        //    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        //    0x00, 0x00, 0x36, 0xe5, 0xf6, 0xb5, 0xc5, 0xe0, 0x60, 0x70, 0xf0, 0xef, 0xca, 0x96,
        //    0x22, 0x7a, 0x86, 0x3e,
        //];
        //let msg = [
        //    0x41, 0x6e, 0x79, 0x20, 0x73, 0x75, 0x62, 0x6d, 0x69, 0x73, 0x73, 0x69, 0x6f, 0x6e,
        //    0x20, 0x74, 0x6f, 0x20, 0x74, 0x68, 0x65, 0x20, 0x49, 0x45, 0x54, 0x46, 0x20, 0x69,
        //    0x6e, 0x74, 0x65, 0x6e, 0x64, 0x65, 0x64, 0x20, 0x62, 0x79, 0x20, 0x74, 0x68, 0x65,
        //    0x20, 0x43, 0x6f, 0x6e, 0x74, 0x72, 0x69, 0x62, 0x75, 0x74, 0x6f, 0x72, 0x20, 0x66,
        //    0x6f, 0x72, 0x20, 0x70, 0x75, 0x62, 0x6c, 0x69, 0x63, 0x61, 0x74, 0x69, 0x6f, 0x6e,
        //    0x20, 0x61, 0x73, 0x20, 0x61, 0x6c, 0x6c, 0x20, 0x6f, 0x72, 0x20, 0x70, 0x61, 0x72,
        //    0x74, 0x20, 0x6f, 0x66, 0x20, 0x61, 0x6e, 0x20, 0x49, 0x45, 0x54, 0x46, 0x20, 0x49,
        //    0x6e, 0x74, 0x65, 0x72, 0x6e, 0x65, 0x74, 0x2d, 0x44, 0x72, 0x61, 0x66, 0x74, 0x20,
        //    0x6f, 0x72, 0x20, 0x52, 0x46, 0x43, 0x20, 0x61, 0x6e, 0x64, 0x20, 0x61, 0x6e, 0x79,
        //    0x20, 0x73, 0x74, 0x61, 0x74, 0x65, 0x6d, 0x65, 0x6e, 0x74, 0x20, 0x6d, 0x61, 0x64,
        //    0x65, 0x20, 0x77, 0x69, 0x74, 0x68, 0x69, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x63,
        //    0x6f, 0x6e, 0x74, 0x65, 0x78, 0x74, 0x20, 0x6f, 0x66, 0x20, 0x61, 0x6e, 0x20, 0x49,
        //    0x45, 0x54, 0x46, 0x20, 0x61, 0x63, 0x74, 0x69, 0x76, 0x69, 0x74, 0x79, 0x20, 0x69,
        //    0x73, 0x20, 0x63, 0x6f, 0x6e, 0x73, 0x69, 0x64, 0x65, 0x72, 0x65, 0x64, 0x20, 0x61,
        //    0x6e, 0x20, 0x22, 0x49, 0x45, 0x54, 0x46, 0x20, 0x43, 0x6f, 0x6e, 0x74, 0x72, 0x69,
        //    0x62, 0x75, 0x74, 0x69, 0x6f, 0x6e, 0x22, 0x2e, 0x20, 0x53, 0x75, 0x63, 0x68, 0x20,
        //    0x73, 0x74, 0x61, 0x74, 0x65, 0x6d, 0x65, 0x6e, 0x74, 0x73, 0x20, 0x69, 0x6e, 0x63,
        //    0x6c, 0x75, 0x64, 0x65, 0x20, 0x6f, 0x72, 0x61, 0x6c, 0x20, 0x73, 0x74, 0x61, 0x74,
        //    0x65, 0x6d, 0x65, 0x6e, 0x74, 0x73, 0x20, 0x69, 0x6e, 0x20, 0x49, 0x45, 0x54, 0x46,
        //    0x20, 0x73, 0x65, 0x73, 0x73, 0x69, 0x6f, 0x6e, 0x73, 0x2c, 0x20, 0x61, 0x73, 0x20,
        //    0x77, 0x65, 0x6c, 0x6c, 0x20, 0x61, 0x73, 0x20, 0x77, 0x72, 0x69, 0x74, 0x74, 0x65,
        //    0x6e, 0x20, 0x61, 0x6e, 0x64, 0x20, 0x65, 0x6c, 0x65, 0x63, 0x74, 0x72, 0x6f, 0x6e,
        //    0x69, 0x63, 0x20, 0x63, 0x6f, 0x6d, 0x6d, 0x75, 0x6e, 0x69, 0x63, 0x61, 0x74, 0x69,
        //    0x6f, 0x6e, 0x73, 0x20, 0x6d, 0x61, 0x64, 0x65, 0x20, 0x61, 0x74, 0x20, 0x61, 0x6e,
        //    0x79, 0x20, 0x74, 0x69, 0x6d, 0x65, 0x20, 0x6f, 0x72, 0x20, 0x70, 0x6c, 0x61, 0x63,
        //    0x65, 0x2c, 0x20, 0x77, 0x68, 0x69, 0x63, 0x68, 0x20, 0x61, 0x72, 0x65, 0x20, 0x61,
        //    0x64, 0x64, 0x72, 0x65, 0x73, 0x73, 0x65, 0x64, 0x20, 0x74, 0x6f,
        //];
        //let tag = [
        //    0x36, 0xe5, 0xf6, 0xb5, 0xc5, 0xe0, 0x60, 0x70, 0xf0, 0xef, 0xca, 0x96, 0x22, 0x7a,
        //    0x86, 0x3e,
        //];
        //assert_eq!(Poly1305::auth(&msg, &otk), tag);
        //
        //let otk = [
        //    0x36, 0xe5, 0xf6, 0xb5, 0xc5, 0xe0, 0x60, 0x70, 0xf0, 0xef, 0xca, 0x96, 0x22, 0x7a,
        //    0x86, 0x3e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        //    0x00, 0x00, 0x00, 0x00,
        //];
        //let msg = [
        //    0x41, 0x6e, 0x79, 0x20, 0x73, 0x75, 0x62, 0x6d, 0x69, 0x73, 0x73, 0x69, 0x6f, 0x6e,
        //    0x20, 0x74, 0x6f, 0x20, 0x74, 0x68, 0x65, 0x20, 0x49, 0x45, 0x54, 0x46, 0x20, 0x69,
        //    0x6e, 0x74, 0x65, 0x6e, 0x64, 0x65, 0x64, 0x20, 0x62, 0x79, 0x20, 0x74, 0x68, 0x65,
        //    0x20, 0x43, 0x6f, 0x6e, 0x74, 0x72, 0x69, 0x62, 0x75, 0x74, 0x6f, 0x72, 0x20, 0x66,
        //    0x6f, 0x72, 0x20, 0x70, 0x75, 0x62, 0x6c, 0x69, 0x63, 0x61, 0x74, 0x69, 0x6f, 0x6e,
        //    0x20, 0x61, 0x73, 0x20, 0x61, 0x6c, 0x6c, 0x20, 0x6f, 0x72, 0x20, 0x70, 0x61, 0x72,
        //    0x74, 0x20, 0x6f, 0x66, 0x20, 0x61, 0x6e, 0x20, 0x49, 0x45, 0x54, 0x46, 0x20, 0x49,
        //    0x6e, 0x74, 0x65, 0x72, 0x6e, 0x65, 0x74, 0x2d, 0x44, 0x72, 0x61, 0x66, 0x74, 0x20,
        //    0x6f, 0x72, 0x20, 0x52, 0x46, 0x43, 0x20, 0x61, 0x6e, 0x64, 0x20, 0x61, 0x6e, 0x79,
        //    0x20, 0x73, 0x74, 0x61, 0x74, 0x65, 0x6d, 0x65, 0x6e, 0x74, 0x20, 0x6d, 0x61, 0x64,
        //    0x65, 0x20, 0x77, 0x69, 0x74, 0x68, 0x69, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x63,
        //    0x6f, 0x6e, 0x74, 0x65, 0x78, 0x74, 0x20, 0x6f, 0x66, 0x20, 0x61, 0x6e, 0x20, 0x49,
        //    0x45, 0x54, 0x46, 0x20, 0x61, 0x63, 0x74, 0x69, 0x76, 0x69, 0x74, 0x79, 0x20, 0x69,
        //    0x73, 0x20, 0x63, 0x6f, 0x6e, 0x73, 0x69, 0x64, 0x65, 0x72, 0x65, 0x64, 0x20, 0x61,
        //    0x6e, 0x20, 0x22, 0x49, 0x45, 0x54, 0x46, 0x20, 0x43, 0x6f, 0x6e, 0x74, 0x72, 0x69,
        //    0x62, 0x75, 0x74, 0x69, 0x6f, 0x6e, 0x22, 0x2e, 0x20, 0x53, 0x75, 0x63, 0x68, 0x20,
        //    0x73, 0x74, 0x61, 0x74, 0x65, 0x6d, 0x65, 0x6e, 0x74, 0x73, 0x20, 0x69, 0x6e, 0x63,
        //    0x6c, 0x75, 0x64, 0x65, 0x20, 0x6f, 0x72, 0x61, 0x6c, 0x20, 0x73, 0x74, 0x61, 0x74,
        //    0x65, 0x6d, 0x65, 0x6e, 0x74, 0x73, 0x20, 0x69, 0x6e, 0x20, 0x49, 0x45, 0x54, 0x46,
        //    0x20, 0x73, 0x65, 0x73, 0x73, 0x69, 0x6f, 0x6e, 0x73, 0x2c, 0x20, 0x61, 0x73, 0x20,
        //    0x77, 0x65, 0x6c, 0x6c, 0x20, 0x61, 0x73, 0x20, 0x77, 0x72, 0x69, 0x74, 0x74, 0x65,
        //    0x6e, 0x20, 0x61, 0x6e, 0x64, 0x20, 0x65, 0x6c, 0x65, 0x63, 0x74, 0x72, 0x6f, 0x6e,
        //    0x69, 0x63, 0x20, 0x63, 0x6f, 0x6d, 0x6d, 0x75, 0x6e, 0x69, 0x63, 0x61, 0x74, 0x69,
        //    0x6f, 0x6e, 0x73, 0x20, 0x6d, 0x61, 0x64, 0x65, 0x20, 0x61, 0x74, 0x20, 0x61, 0x6e,
        //    0x79, 0x20, 0x74, 0x69, 0x6d, 0x65, 0x20, 0x6f, 0x72, 0x20, 0x70, 0x6c, 0x61, 0x63,
        //    0x65, 0x2c, 0x20, 0x77, 0x68, 0x69, 0x63, 0x68, 0x20, 0x61, 0x72, 0x65, 0x20, 0x61,
        //    0x64, 0x64, 0x72, 0x65, 0x73, 0x73, 0x65, 0x64, 0x20, 0x74, 0x6f,
        //];
        //let tag = [
        //    0xf3, 0x47, 0x7e, 0x7c, 0xd9, 0x54, 0x17, 0xaf, 0x89, 0xa6, 0xb8, 0x79, 0x4c, 0x31,
        //    0x0c, 0xf0,
        //];
        //assert_eq!(Poly1305::auth(&msg, &otk), tag);
        //
        //let otk = [
        //    0x1c, 0x92, 0x40, 0xa5, 0xeb, 0x55, 0xd3, 0x8a, 0xf3, 0x33, 0x88, 0x86, 0x04, 0xf6,
        //    0xb5, 0xf0, 0x47, 0x39, 0x17, 0xc1, 0x40, 0x2b, 0x80, 0x09, 0x9d, 0xca, 0x5c, 0xbc,
        //    0x20, 0x70, 0x75, 0xc0,
        //];
        //let msg = [
        //    0x27, 0x54, 0x77, 0x61, 0x73, 0x20, 0x62, 0x72, 0x69, 0x6c, 0x6c, 0x69, 0x67, 0x2c,
        //    0x20, 0x61, 0x6e, 0x64, 0x20, 0x74, 0x68, 0x65, 0x20, 0x73, 0x6c, 0x69, 0x74, 0x68,
        //    0x79, 0x20, 0x74, 0x6f, 0x76, 0x65, 0x73, 0x0a, 0x44, 0x69, 0x64, 0x20, 0x67, 0x79,
        //    0x72, 0x65, 0x20, 0x61, 0x6e, 0x64, 0x20, 0x67, 0x69, 0x6d, 0x62, 0x6c, 0x65, 0x20,
        //    0x69, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x77, 0x61, 0x62, 0x65, 0x3a, 0x0a, 0x41,
        //    0x6c, 0x6c, 0x20, 0x6d, 0x69, 0x6d, 0x73, 0x79, 0x20, 0x77, 0x65, 0x72, 0x65, 0x20,
        //    0x74, 0x68, 0x65, 0x20, 0x62, 0x6f, 0x72, 0x6f, 0x67, 0x6f, 0x76, 0x65, 0x73, 0x2c,
        //    0x0a, 0x41, 0x6e, 0x64, 0x20, 0x74, 0x68, 0x65, 0x20, 0x6d, 0x6f, 0x6d, 0x65, 0x20,
        //    0x72, 0x61, 0x74, 0x68, 0x73, 0x20, 0x6f, 0x75, 0x74, 0x67, 0x72, 0x61, 0x62, 0x65,
        //    0x2e,
        //];
        //let tag = [
        //    0x45, 0x41, 0x66, 0x9a, 0x7e, 0xaa, 0xee, 0x61, 0xe7, 0x08, 0xdc, 0x7c, 0xbc, 0xc5,
        //    0xeb, 0x62,
        //];
        //assert_eq!(Poly1305::auth(&msg, &otk), tag);
        //
        let otk = [
            0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00,
        ];
        let msg = [0xff; 16];
        let tag = [
            0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00,
        ];
        assert_eq!(Poly1305::auth(&msg, &otk), tag);

        let otk = [
            0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
            0xff, 0xff, 0xff, 0xff,
        ];
        let msg = [
            0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00,
        ];
        let tag = [
            0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00,
        ];
        assert_eq!(Poly1305::auth(&msg, &otk), tag);

        let otk = [
            0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00,
        ];
        let msg = [
            0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
            0xff, 0xff, 0xf0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
            0xff, 0xff, 0xff, 0xff, 0x11, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        ];
        let tag = [
            0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00,
        ];
        assert_eq!(Poly1305::auth(&msg, &otk), tag);

        let otk = [
            0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00,
        ];
        let msg = [
            0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
            0xff, 0xff, 0xfb, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe,
            0xfe, 0xfe, 0xfe, 0xfe, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
            0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
        ];
        let tag = [0; 16];
        assert_eq!(Poly1305::auth(&msg, &otk), tag);

        let otk = [
            0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00,
        ];
        let msg = [
            0xfd, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
            0xff, 0xff,
        ];
        let tag = [
            0xfa, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
            0xff, 0xff,
        ];
        assert_eq!(Poly1305::auth(&msg, &otk), tag);

        let otk = [
            0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00,
        ];
        let msg = [
            0xe3, 0x35, 0x94, 0xd7, 0x50, 0x5e, 0x43, 0xb9, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x33, 0x94, 0xd7, 0x50, 0x5e, 0x43, 0x79, 0xcd, 0x01, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        ];
        let tag = [
            0x14, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x55, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00,
        ];
        assert_eq!(Poly1305::auth(&msg, &otk), tag);

        let otk = [
            0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00,
        ];
        let msg = [
            0xe3, 0x35, 0x94, 0xd7, 0x50, 0x5e, 0x43, 0xb9, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x33, 0x94, 0xd7, 0x50, 0x5e, 0x43, 0x79, 0xcd, 0x01, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        ];
        let tag = [
            0x13, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00,
        ];
        assert_eq!(Poly1305::auth(&msg, &otk), tag);
    }
}