crypto-async-rs 0.1.3

use futures::{AsyncWrite, io::{self, AsyncRead, AsyncReadExt, AsyncWriteExt}};
use std::{pin::Pin, task::{Context, Poll}};

fn cha_cha_quarter_round(
    state: &mut [u32; 16],
    a_index: usize,
    b_index: usize,
    c_index: usize,
    d_index: usize,
) {
    let mut a = state[a_index];
    let mut b = state[b_index];
    let mut c = state[c_index];
    let mut d = state[d_index];

    a = a.wrapping_add(b);
    d = d ^ a;
    d = d.rotate_left(16);

    c = c.wrapping_add(d);
    b = b ^ c;
    b = b.rotate_left(12);

    a = a.wrapping_add(b);
    d = d ^ a;
    d = d.rotate_left(8);

    c = c.wrapping_add(d);
    b = b ^ c;
    b = b.rotate_left(7);

    state[a_index] = a;
    state[b_index] = b;
    state[c_index] = c;
    state[d_index] = d;
}

fn cha_cha_20_block(key: &[u8; 32], counter: u32, nonce: &[u8; 12]) -> [u8; 64] {
    let mut key_words = [0u32; 8];
    for i in 0..8 {
        key_words[i] = u32::from_le_bytes([
            key[4*i],
            key[4*i + 1],
            key[4*i + 2],
            key[4*i + 3],
        ]);
    }

    let mut nonce_words = [0u32; 3];
    for i in 0..3 {
        nonce_words[i] = u32::from_le_bytes([
            nonce[4*i],
            nonce[4*i + 1],
            nonce[4*i + 2],
            nonce[4*i + 3],
        ]);
    }

    let [k0,k1,k2,k3,k4,k5,k6,k7] = key_words;
    let [n0,n1,n2] = nonce_words;

    let mut state: [u32; 16] = [
        0x6170_7865, 0x3320_646e, 0x7962_2d32, 0x6b20_6574,
        k0, k1, k2, k3, k4, k5, k6, k7,
        counter,
        n0, n1, n2,
    ];

    let mut working_state = state;

    for _ in 0..10 {
        cha_cha_quarter_round(&mut working_state, 0, 4, 8, 12);
        cha_cha_quarter_round(&mut working_state, 1, 5, 9, 13);
        cha_cha_quarter_round(&mut working_state, 2, 6, 10, 14);
        cha_cha_quarter_round(&mut working_state, 3, 7, 11, 15);

        cha_cha_quarter_round(&mut working_state, 0, 5, 10, 15);
        cha_cha_quarter_round(&mut working_state, 1, 6, 11, 12);
        cha_cha_quarter_round(&mut working_state, 2, 7, 8, 13);
        cha_cha_quarter_round(&mut working_state, 3, 4, 9, 14);
    }

    for i in 0..16 {
        state[i] = state[i].wrapping_add(working_state[i]);
    }

    let mut out = [0u8; 64];
    for (i, word) in state.iter().enumerate() {
        out[4*i..4*i+4].copy_from_slice(&word.to_le_bytes());
    }
    out
}

pub async fn cha_cha_20_encrypt<R, W>(
    key: &[u8; 32],
    mut counter: u32,
    nonce: &[u8; 12],
    mut reader: R,
    mut writer: W,
) -> io::Result<()> 
    where 
        R: AsyncRead + Unpin,
        W: AsyncWrite + Unpin
{
    let mut buf = [0u8; 4096];
    let mut block_off = 0usize;
    let mut keystream = [0u8; 64];

    loop {
        let n = reader.read(&mut buf).await?;
        if n == 0 { break; }

        let mut i = 0;
        while i < n {
            if block_off == 0 {
                keystream = cha_cha_20_block(key, counter, nonce);
            }
            let take = core::cmp::min(64 - block_off, n - i);
            for j in 0..take {
                buf[i + j] ^= keystream[block_off + j];
            }
            i += take;
            block_off += take;
            if block_off == 64 {
                block_off = 0;
                counter = counter.wrapping_add(1);
            }
        }
         writer.write_all(&buf[..n]).await?;
    }
    writer.flush().await?;
    Ok(())
}


#[derive(Clone, Copy)]
struct Poly1305 {
    accumulator: [u32; 5],
    r: [u32; 4],
    s: [u32; 4],
    buffer: [u8; 16],
    buffer_len: usize,
}

impl Poly1305 {
    pub fn new(key: &[u8; 32]) -> Self {
        let mut r = [0u32; 4];
        let mut s = [0u32; 4];
        for i in 0..4 {
            let j = 4 * i;
            r[i] = u32::from_le_bytes([key[j], key[j + 1], key[j + 2], key[j + 3]]);
            s[i] = u32::from_le_bytes([
                key[16 + j],
                key[16 + j + 1],
                key[16 + j + 2],
                key[16 + j + 3],
            ]);
        }
        r[0] &= 0x0fffffff;
        r[1] &= 0x0ffffffc;
        r[2] &= 0x0ffffffc;
        r[3] &= 0x0ffffffc;

        Self {
            accumulator: [0; 5],
            r,
            s,
            buffer: [0; 16],
            buffer_len: 0,
        }
    }

    pub fn update(&mut self, mut data: &[u8]) {
        while !data.is_empty() {
            let to_copy = std::cmp::min(16 - self.buffer_len, data.len());
            self.buffer[self.buffer_len..self.buffer_len + to_copy]
                .copy_from_slice(&data[0..to_copy]);
            self.buffer_len += to_copy;
            data = &data[to_copy..];

            if self.buffer_len == 16 {
                let mut block = [0u32; 4];
                for i in 0..4 {
                    let j = 4 * i;
                    block[i] = u32::from_le_bytes([
                        self.buffer[j],
                        self.buffer[j + 1],
                        self.buffer[j + 2],
                        self.buffer[j + 3],
                    ]);
                }
                let extended_block = [block[0], block[1], block[2], block[3], 1];
                self.accumulator = poly1305_add(self.accumulator, extended_block);
                poly1305_mul(&mut self.accumulator, self.r);
                self.buffer_len = 0;
            }
        }
    }

    pub fn finalize(mut self) -> [u8; 16] {
        if self.buffer_len > 0 {
            self.buffer[self.buffer_len] = 1;
            for i in self.buffer_len + 1..16 {
                self.buffer[i] = 0;
            }
             let mut block = [0u32; 4];
            for i in 0..4 {
                let j = 4 * i;
                block[i] = u32::from_le_bytes([
                    self.buffer[j],
                    self.buffer[j + 1],
                    self.buffer[j + 2],
                    self.buffer[j + 3],
                ]);
            }
            let extended_block = [block[0], block[1], block[2], block[3], 0];
            self.accumulator = poly1305_add(self.accumulator, extended_block);
            poly1305_mul(&mut self.accumulator, self.r);
        }
        self.accumulator = poly1305_mod(self.accumulator);
        let extended_s = [self.s[0], self.s[1], self.s[2], self.s[3], 0];
        self.accumulator = poly1305_add(self.accumulator, extended_s);
        let mut out = [0u8; 16];
        for (i, limb) in self.accumulator[..4].iter().enumerate() {
            out[4 * i..4 * i + 4].copy_from_slice(&limb.to_le_bytes());
        }
        out
    }
}

pub async fn poly1305_mac_async<R: AsyncRead + Unpin>(
    key: &[u8; 32],
    mut reader: R,
) -> io::Result<[u8; 16]> {
    let mut state = Poly1305::new(key);
    let mut buf = [0u8; 1024];
    loop {
        let n = reader.read(&mut buf).await?;
        if n == 0 {
            break;
        }
        state.update(&buf[0..n]);
    }
    Ok(state.finalize())
}

// Multiplies h and r, put the result in h
fn poly1305_mul(h: &mut [u32; 5], r: [u32; 4]) {
    // These would fit in 32 bits, but we need 64 bit multiplications
    let r0: u64 = r[0] as u64;
    let r1: u64 = r[1] as u64;
    let r2: u64 = r[2] as u64;
    let r3: u64 = r[3] as u64;

    let h0: u64 = h[0] as u64;
    let h1: u64 = h[1] as u64;
    let h2: u64 = h[2] as u64;
    let h3: u64 = h[3] as u64;
    let h4: u64 = h[4] as u64;

    let rr0 = (r0 >> 2) * 5; // lose 2 bottom bits...
    let rr1 = (r1 >> 2) * 5; // 2 bottom bits already cleared
    let rr2 = (r2 >> 2) * 5; // 2 bottom bits already cleared
    let rr3 = (r3 >> 2) * 5; // 2 bottom bits already cleared

    // school book modular multiplication (without carry propagation)
    let x0: u64 = h0 * r0 + h1 * rr3 + h2 * rr2 + h3 * rr1 + h4 * rr0;
    let x1 = h0 * r1 + h1 * r0 + h2 * rr3 + h3 * rr2 + h4 * rr1;
    let x2 = h0 * r2 + h1 * r1 + h2 * r0 + h3 * rr3 + h4 * rr2;
    let x3 = h0 * r3 + h1 * r2 + h2 * r1 + h3 * r0 + h4 * rr3;
    let x4 = h4 * (r0 & 3); // ...recover those 2 bits

    // carry propagation (put the result back in h)
    let msb: u64 = x4 + (x3 >> 32);
    let mut u = (msb >> 2) * 5; // lose 2 bottom bits...
    u += x0 & 0xffffffff;
    h[0] = (u & 0xffffffff) as u32;
    u >>= 32;
    u += (x1 & 0xffffffff) + (x0 >> 32);
    h[1] = (u & 0xffffffff) as u32;
    u >>= 32;
    u += (x2 & 0xffffffff) + (x1 >> 32);
    h[2] = (u & 0xffffffff) as u32;
    u >>= 32;
    u += (x3 & 0xffffffff) + (x2 >> 32);
    h[3] = (u & 0xffffffff) as u32;
    u >>= 32;
    u += msb & 3 /* ...recover them */;
    h[4] = u as u32;
}

fn poly1305_add(a: [u32; 5], b: [u32; 5]) -> [u32; 5] {
    let mut temp: u64 = 0;
    let mut result: [u32; 5] = Default::default();

    //Compute R = A + B
    for i in 0..5 {
        temp += a[i] as u64 + b[i] as u64;
        result[i] = temp as u32;
        temp >>= 32;
    }

    result
}

fn poly1305_mod(a: [u32; 5]) -> [u32; 5] {
    if a[4] < 3 {
        return a;
    }

    let low_p = 0xfffffffffffffffffffffffffffffffbu128;
    let low_a: u128 =
        a[0] as u128
        | ((a[1] as u128) << 32)
        | ((a[2] as u128) << 64)
        | ((a[3] as u128) << 96);
    if a[4] == 3 && low_p > low_a {
        return a;
    }
    if a[4] == 3 && low_p == low_a {
        return [0, 0, 0, 0, 0];
    }

    let mut hi_a = a[4];
    let low_result = if low_a >= low_p {
        low_a - low_p
    } else {
        hi_a -= 1;
        !low_p + 1 + low_a
    };

    let bytes = low_result.to_le_bytes();
    let low_result = [
        u32::from_le_bytes([bytes[0], bytes[1], bytes[2], bytes[3]]),
        u32::from_le_bytes([bytes[4], bytes[5], bytes[6], bytes[7]]),
        u32::from_le_bytes([bytes[8], bytes[9], bytes[10], bytes[11]]),
        u32::from_le_bytes([bytes[12], bytes[13], bytes[14], bytes[15]]),
    ];
    [
        low_result[0],
        low_result[1],
        low_result[2],
        low_result[3],
        hi_a - 3,
    ]
}

pub fn poly1305_key_gen(key: &[u8; 32], nonce: &[u8; 12]) -> [u8; 32] {
    let counter = 0;
    let block = &cha_cha_20_block(key, counter, nonce)[..32];
    let mut result: [u8; 32] = [0; 32];
    result.copy_from_slice(block);
    result
}

struct TeeReader<'a, R: AsyncRead + Unpin> {
    reader: R,
    poly: &'a mut Poly1305,
    cipher_len: u64,
}

impl<'a, R: AsyncRead + Unpin> TeeReader<'a, R> {
    fn new(reader: R, poly: &'a mut Poly1305) -> Self {
        Self {
            reader,
            poly,
            cipher_len: 0,
        }
    }
}

impl<'a, R: AsyncRead + Unpin> AsyncRead for TeeReader<'a, R> {
    fn poll_read(
        mut self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &mut [u8],
    ) -> Poll<io::Result<usize>> {
        let n = futures::ready!(Pin::new(&mut self.reader).poll_read(cx, buf))?;
        if n > 0 {
            self.poly.update(&buf[..n]);
            self.cipher_len += n as u64;
        }
        Poll::Ready(Ok(n))
    }
}

struct TeeWriter<'a, W: AsyncWrite + Unpin> {
    writer: W,
    poly: &'a mut Poly1305,
    cipher_len: u64,
}

impl<'a, W: AsyncWrite + Unpin> TeeWriter<'a, W> {
    fn new(writer: W, poly: &'a mut Poly1305) -> Self {
        Self {
            writer,
            poly,
            cipher_len: 0,
        }
    }
}

impl<'a, W: AsyncWrite + Unpin> AsyncWrite for TeeWriter<'a, W> {
    fn poll_write(
        mut self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &[u8],
    ) -> Poll<io::Result<usize>> {
        let n = futures::ready!(Pin::new(&mut self.writer).poll_write(cx, buf))?;
        self.poly.update(&buf[..n]);
        self.cipher_len += n as u64;
        Poll::Ready(Ok(n))
    }

    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
        Pin::new(&mut self.writer).poll_flush(cx)
    }

    fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
        Pin::new(&mut self.writer).poll_close(cx)
    }
}


pub async fn cha_cha_20_aead_encrypt<R: AsyncRead + Unpin, W: AsyncWrite + Unpin>(
    aad: &[u8],
    key: &[u8; 32],
    nonce: [u8; 12],
    reader: R,
    mut writer: W,
) -> io::Result<[u8; 16]> {
    let otk = poly1305_key_gen(key, &nonce);
    let mut poly = Poly1305::new(&otk);

    poly.update(aad);
    let aad_pad = (16 - aad.len() % 16) % 16;
    if aad_pad > 0 {
        let zero_pad = [0u8; 16];
        poly.update(&zero_pad[..aad_pad]);
    }

    let mut tee_writer = TeeWriter::new(&mut writer, &mut poly);
    cha_cha_20_encrypt(key, 1u32, &nonce, reader, &mut tee_writer).await?;

    let cipher_len = tee_writer.cipher_len;
    let cipher_pad = (16 - (cipher_len as usize % 16)) % 16;
    tee_writer.flush().await?;
    if cipher_pad > 0 {
        let zero_pad = [0u8; 16];
        poly.update(&zero_pad[..cipher_pad]);
    }

    let aad_len_bytes: [u8; 8] = (aad.len() as u64).to_le_bytes();
    let cipher_len_bytes: [u8; 8] = cipher_len.to_le_bytes();
    poly.update(&aad_len_bytes);
    poly.update(&cipher_len_bytes);

    let tag = poly.finalize();
    Ok(tag)
}

pub async fn cha_cha_20_aead_decrypt_verify<R, W>(
    aad: &[u8],
    key: &[u8; 32],
    nonce: [u8; 12],
    reader: R,
    writer: W,
    expected_tag: [u8; 16],
) -> io::Result<()> 
where 
    R: AsyncRead + Unpin,
    W: AsyncWrite + Unpin
{
    let otk = poly1305_key_gen(key, &nonce);
    let mut poly = Poly1305::new(&otk);

    poly.update(aad);
    let aad_pad = (16 - aad.len() % 16) % 16;
    if aad_pad != 0 {
        let zero_pad = [0u8; 16];
        poly.update(&zero_pad[..aad_pad]);
    }

    let mut tee_reader = TeeReader::new(reader, &mut poly);
    cha_cha_20_encrypt(key, 1u32, &nonce, &mut tee_reader, writer).await?;

    let cipher_len = tee_reader.cipher_len;
    let c_pad = (16 - (cipher_len as usize % 16)) % 16;
    if c_pad != 0 {
        let zero_pad = [0u8; 16];
        poly.update(&zero_pad[..c_pad]);
    }

    let aad_len_le = (aad.len() as u64).to_le_bytes();
    let c_len_le = (cipher_len as u64).to_le_bytes();
    poly.update(&aad_len_le);
    poly.update(&c_len_le);

    let tag = poly.finalize();
    let mut diff: u8 = 0;
    for i in 0..16 {
        diff |= tag[i] ^ expected_tag[i];
    }
    if diff != 0 {
        return Err(io::Error::new(io::ErrorKind::InvalidData, "AEAD tag mismatch"));
    }

    Ok(())
}


#[cfg(test)]
mod tests {
    use futures::executor::block_on;

    use super::*;

    const PLAIN_TEXT_1:&[u8] = &[
        0x4c, 0x61, 0x64, 0x69, 0x65, 0x73, 0x20, 0x61, 0x6e, 0x64, 0x20, 0x47, 0x65, 0x6e,
        0x74, 0x6c, 0x65, 0x6d, 0x65, 0x6e, 0x20, 0x6f, 0x66, 0x20, 0x74, 0x68, 0x65, 0x20,
        0x63, 0x6c, 0x61, 0x73, 0x73, 0x20, 0x6f, 0x66, 0x20, 0x27, 0x39, 0x39, 0x3a, 0x20,
        0x49, 0x66, 0x20, 0x49, 0x20, 0x63, 0x6f, 0x75, 0x6c, 0x64, 0x20, 0x6f, 0x66, 0x66,
        0x65, 0x72, 0x20, 0x79, 0x6f, 0x75, 0x20, 0x6f, 0x6e, 0x6c, 0x79, 0x20, 0x6f, 0x6e,
        0x65, 0x20, 0x74, 0x69, 0x70, 0x20, 0x66, 0x6f, 0x72, 0x20, 0x74, 0x68, 0x65, 0x20,
        0x66, 0x75, 0x74, 0x75, 0x72, 0x65, 0x2c, 0x20, 0x73, 0x75, 0x6e, 0x73, 0x63, 0x72,
        0x65, 0x65, 0x6e, 0x20, 0x77, 0x6f, 0x75, 0x6c, 0x64, 0x20, 0x62, 0x65, 0x20, 0x69,
        0x74, 0x2e
    ];

    const CIPHER_TEXT1: &[u8] = &[
        0xd3, 0x1a, 0x8d, 0x34, 0x64, 0x8e, 0x60, 0xdb, 0x7b, 0x86, 0xaf, 0xbc, 0x53, 0xef,
        0x7e, 0xc2, 0xa4, 0xad, 0xed, 0x51, 0x29, 0x6e, 0x08, 0xfe, 0xa9, 0xe2, 0xb5, 0xa7,
        0x36, 0xee, 0x62, 0xd6, 0x3d, 0xbe, 0xa4, 0x5e, 0x8c, 0xa9, 0x67, 0x12, 0x82, 0xfa,
        0xfb, 0x69, 0xda, 0x92, 0x72, 0x8b, 0x1a, 0x71, 0xde, 0x0a, 0x9e, 0x06, 0x0b, 0x29,
        0x05, 0xd6, 0xa5, 0xb6, 0x7e, 0xcd, 0x3b, 0x36, 0x92, 0xdd, 0xbd, 0x7f, 0x2d, 0x77,
        0x8b, 0x8c, 0x98, 0x03, 0xae, 0xe3, 0x28, 0x09, 0x1b, 0x58, 0xfa, 0xb3, 0x24, 0xe4,
        0xfa, 0xd6, 0x75, 0x94, 0x55, 0x85, 0x80, 0x8b, 0x48, 0x31, 0xd7, 0xbc, 0x3f, 0xf4,
        0xde, 0xf0, 0x8e, 0x4b, 0x7a, 0x9d, 0xe5, 0x76, 0xd2, 0x65, 0x86, 0xce, 0xc6, 0x4b,
        0x61, 0x16,
    ];

    const AAD1: [u8; 12] = [
        0x50, 0x51, 0x52, 0x53, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
    ];

    const KEY1: [u8; 32] = [
        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,
    ];

    const IV1: [u8; 8] = [0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47];
    const TAG1: [u8; 16] = [
        0x1a, 0xe1, 0x0b, 0x59, 0x4f, 0x09, 0xe2, 0x6a, 0x7e, 0x90, 0x2e, 0xcb, 0xd0, 0x60,
        0x06, 0x91,
    ];


    #[test]
    fn test_cha_cha_quarter_round() {
        let mut state: [u32; 16] = [
            0x879531e0, 0xc5ecf37d, 0x516461b1, 0xc9a62f8a, 0x44c20ef3, 0x3390af7f, 0xd9fc690b,
            0x2a5f714c, 0x53372767, 0xb00a5631, 0x974c541a, 0x359e9963, 0x5c971061, 0x3d631689,
            0x2098d9d6, 0x91dbd320,
        ];

        cha_cha_quarter_round(&mut state, 2, 7, 8, 13);

        assert_eq!(
            state,
            [
                0x879531e0, 0xc5ecf37d, 0xbdb886dc, 0xc9a62f8a, 0x44c20ef3, 0x3390af7f, 0xd9fc690b,
                0xcfacafd2, 0xe46bea80, 0xb00a5631, 0x974c541a, 0x359e9963, 0x5c971061, 0xccc07c79,
                0x2098d9d6, 0x91dbd320
            ]
        );
    }

    #[test]
    fn test_cha_cha_20_block() {
        let key: [u8; 32] = [
            0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf, 0x10,
            0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e,
            0x1f,
        ];
        let nonce: [u8; 12] = [0x0, 0x0, 0x0, 0x9, 0x0, 0x0, 0x0, 0x4a, 0x0, 0x0, 0x0, 0x0];

        let state: &[u8] = &cha_cha_20_block(&key, 1u32, &nonce);
        let expected: &[u8] = &[
            0x10u8, 0xf1, 0xe7, 0xe4, 0xd1, 0x3b, 0x59, 0x15, 0x50, 0x0f, 0xdd, 0x1f, 0xa3, 0x20,
            0x71, 0xc4, 0xc7u8, 0xd1, 0xf4, 0xc7, 0x33, 0xc0, 0x68, 0x03, 0x04, 0x22, 0xaa, 0x9a,
            0xc3, 0xd4, 0x6c, 0x4e, 0xd2u8, 0x82, 0x64, 0x46, 0x07, 0x9f, 0xaa, 0x09, 0x14, 0xc2,
            0xd7, 0x05, 0xd9, 0x8b, 0x02, 0xa2, 0xb5u8, 0x12, 0x9c, 0xd1, 0xde, 0x16, 0x4e, 0xb9,
            0xcb, 0xd0, 0x83, 0xe8, 0xa2, 0x50, 0x3c, 0x4e,
        ];

        assert_eq!(state, expected);
    }

    #[test]
    fn test_cha_cha_20_encrypt() {
        let key: [u8; 32] = [
            0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf, 0x10,
            0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e,
            0x1f,
        ];
        let nonce: [u8; 12] = [0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x4a, 0x0, 0x0, 0x0, 0x0];

        let mut cipher_text = vec![];
        block_on(
            cha_cha_20_encrypt(&key, 1, &nonce, PLAIN_TEXT_1, &mut cipher_text)
        ).unwrap();
        let expected: &[u8] = &[
            0x6e, 0x2e, 0x35, 0x9a, 0x25, 0x68, 0xf9, 0x80, 0x41, 0xba, 0x07, 0x28, 0xdd, 0x0d,
            0x69, 0x81, 0xe9, 0x7e, 0x7a, 0xec, 0x1d, 0x43, 0x60, 0xc2, 0x0a, 0x27, 0xaf, 0xcc,
            0xfd, 0x9f, 0xae, 0x0b, 0xf9, 0x1b, 0x65, 0xc5, 0x52, 0x47, 0x33, 0xab, 0x8f, 0x59,
            0x3d, 0xab, 0xcd, 0x62, 0xb3, 0x57, 0x16, 0x39, 0xd6, 0x24, 0xe6, 0x51, 0x52, 0xab,
            0x8f, 0x53, 0x0c, 0x35, 0x9f, 0x08, 0x61, 0xd8, 0x07, 0xca, 0x0d, 0xbf, 0x50, 0x0d,
            0x6a, 0x61, 0x56, 0xa3, 0x8e, 0x08, 0x8a, 0x22, 0xb6, 0x5e, 0x52, 0xbc, 0x51, 0x4d,
            0x16, 0xcc, 0xf8, 0x06, 0x81, 0x8c, 0xe9, 0x1a, 0xb7, 0x79, 0x37, 0x36, 0x5a, 0xf9,
            0x0b, 0xbf, 0x74, 0xa3, 0x5b, 0xe6, 0xb4, 0x0b, 0x8e, 0xed, 0xf2, 0x78, 0x5e, 0x42,
            0x87, 0x4d,
        ];

        assert_eq!(&cipher_text, expected);
    }

    #[test]
    fn test_poly1305_mac() {
        let key_material: [u8; 32] = [
            0x85, 0xd6, 0xbe, 0x78, 0x57, 0x55, 0x6d, 0x33, 0x7f, 0x44, 0x52, 0xfe, 0x42, 0xd5,
            0x06, 0xa8, 0x01, 0x03, 0x80, 0x8a, 0xfb, 0x0d, 0xb2, 0xfd, 0x4a, 0xbf, 0xf6, 0xaf,
            0x41, 0x49, 0xf5, 0x1b,
        ];
        let message:&[u8] = &[
            0x43u8, 0x72, 0x79, 0x70, 0x74, 0x6f, 0x67, 0x72, 0x61, 0x70, 0x68, 0x69, 0x63, 0x20,
            0x46, 0x6f, 0x72, 0x75, 0x6d, 0x20, 0x52, 0x65, 0x73, 0x65, 0x61, 0x72, 0x63, 0x68,
            0x20, 0x47, 0x72, 0x6f, 0x75, 0x70,
        ];

        let tag = block_on(
            poly1305_mac_async(&key_material, message)
        ).unwrap();
        let expected: &[u8] = &[
            0xa8, 0x06, 0x1d, 0xc1, 0x30, 0x51, 0x36, 0xc6, 0xc2, 0x2b, 0x8b, 0xaf, 0x0c, 0x01,
            0x27, 0xa9,
        ];

        assert_eq!(tag, expected);
    }

    #[test]
    fn test_poly1305_key_generation() {
        let nonce: [u8; 12] = [
            0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
        ];
        let result: [u8; 32] = poly1305_key_gen(&KEY1, &nonce);
        let expected: [u8; 32] = [
            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!(&result, &expected);
    }

    #[test]
    fn test_cha_cha_20_aead_encrypt() {
        let constant: [u8; 4] = [0x07, 0x00, 0x00, 0x00];
        let mut constant_and_iv: [u8; 12] = [0; 12];
        constant_and_iv[..4].copy_from_slice(&constant);
        constant_and_iv[4..].copy_from_slice(&IV1);

        let mut cipher_text = vec![];
        let tag = block_on(
            cha_cha_20_aead_encrypt(
                &AAD1,
                &KEY1,
                constant_and_iv,
                PLAIN_TEXT_1,
                &mut cipher_text
            )
        ).unwrap();

        assert_eq!(&cipher_text, CIPHER_TEXT1);
        assert_eq!(tag, TAG1);
    }

    #[test]
    fn test_cha_cha_20_aead_decrypt() {
        let constant: [u8; 4] = [0x07, 0x00, 0x00, 0x00];
        let mut constant_and_iv: [u8; 12] = [0; 12];
        constant_and_iv[..4].copy_from_slice(&constant);
        constant_and_iv[4..].copy_from_slice(&IV1);

        let mut plain_text = vec![];
        block_on(cha_cha_20_aead_decrypt_verify(
            &AAD1,
            &KEY1,
            constant_and_iv,
            CIPHER_TEXT1,
            &mut plain_text,
            TAG1
        ))
        .unwrap();

        assert_eq!(&plain_text, PLAIN_TEXT_1);
        // assert_eq!(&tag, &expected_tag);
    }

    #[test]
    fn test_poly1305_mac_2() {
        let otk = [
            0xfd, 0x72, 0xb9, 0xc9, 0x9a, 0xa1, 0x50, 0x9c, 0xd4, 0x7e, 0x72, 0x27, 0x0a, 0xc2,
            0xbf, 0x07, 0xc9, 0x21, 0x98, 0xb5, 0x77, 0xfc, 0x73, 0xaa, 0x0f, 0x36, 0x3c, 0xf6,
            0x38, 0xd3, 0xa6, 0xd7,
        ];
        let message: &[u8] = &[
            0x17, 0x03, 0x03, 0x03, 0xf9, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x6e, 0xc9, 0x75, 0x08, 0x7a, 0x1a, 0x86, 0x19, 0x66, 0x0f, 0x02, 0x13,
            0x67, 0x92, 0x64, 0x11, 0xe8, 0xbb, 0x85, 0x8f, 0xab, 0xd2, 0xad, 0xf5, 0xfe, 0xa9,
            0xfe, 0xb5, 0x35, 0x4f, 0x81, 0xc1, 0x21, 0xe3, 0xf3, 0x02, 0xe1, 0x2a, 0xbc, 0x55,
            0xa8, 0xd5, 0xa7, 0x08, 0xcd, 0x0e, 0xa9, 0x7d, 0x27, 0x78, 0x8b, 0xe8, 0xf3, 0x7a,
            0x6d, 0x44, 0x8c, 0x92, 0xbc, 0x16, 0x13, 0xe5, 0x59, 0x94, 0x9a, 0xde, 0xe0, 0x14,
            0x29, 0xd4, 0xf6, 0x44, 0x20, 0xb1, 0xa7, 0xc3, 0xb7, 0x7d, 0xa9, 0x91, 0xd5, 0x2a,
            0xa8, 0x0f, 0x90, 0xfc, 0x38, 0x01, 0x27, 0xa4, 0x6b, 0x16, 0xdb, 0x75, 0x0b, 0x06,
            0x7a, 0x13, 0xbb, 0xf2, 0x95, 0xbb, 0x2e, 0x07, 0x81, 0x92, 0xe1, 0x05, 0x42, 0xd6,
            0x2e, 0xda, 0xb8, 0xb8, 0x65, 0x95, 0xc7, 0x36, 0x1e, 0x68, 0x17, 0x0c, 0xf3, 0x57,
            0xdf, 0x2f, 0x60, 0x32, 0x36, 0xdc, 0x57, 0x98, 0x46, 0x22, 0x3c, 0x9f, 0x2d, 0xb6,
            0xd2, 0x7c, 0xbf, 0x70, 0xe1, 0x82, 0xb5, 0x2e, 0x92, 0xb3, 0x04, 0x3d, 0x17, 0x81,
            0xde, 0x37, 0x59, 0xa4, 0x12, 0xf2, 0x55, 0xf0, 0x95, 0x82, 0x03, 0xaa, 0x52, 0x89,
            0xe8, 0x71, 0x70, 0xf7, 0x5a, 0x5f, 0x5c, 0x0d, 0x34, 0x52, 0xc4, 0xb4, 0x65, 0xb6,
            0x5f, 0x99, 0xf2, 0x0e, 0x02, 0x1e, 0x24, 0xcb, 0xdc, 0x1d, 0xd2, 0xb7, 0x3c, 0x8a,
            0x4a, 0x64, 0x3a, 0x76, 0xa8, 0x99, 0x60, 0x38, 0x78, 0x53, 0x7e, 0x85, 0xf6, 0x20,
            0xb7, 0xf4, 0x7d, 0x0a, 0x6c, 0x9c, 0x4d, 0x18, 0xea, 0xa8, 0xdf, 0xf6, 0x18, 0x86,
            0xab, 0x5a, 0x8a, 0x9e, 0xdf, 0x13, 0xa0, 0x14, 0x0f, 0xae, 0x33, 0x9c, 0x70, 0x0a,
            0x68, 0x24, 0xc3, 0x34, 0x06, 0x08, 0xe4, 0xdc, 0x1d, 0xeb, 0xa9, 0x49, 0xf4, 0x72,
            0x9f, 0xd5, 0x4c, 0xaa, 0xa8, 0xf7, 0xc2, 0x3f, 0xf0, 0xd8, 0x0e, 0xe9, 0x1e, 0xb1,
            0x21, 0x04, 0x98, 0x3e, 0x4c, 0x8e, 0xa1, 0x5c, 0x1a, 0x69, 0x8e, 0x7a, 0x6c, 0x06,
            0xaa, 0x43, 0xbd, 0x5f, 0x56, 0x24, 0x98, 0xd7, 0x12, 0xd3, 0x1c, 0x2e, 0x6c, 0xd9,
            0x35, 0x25, 0x28, 0x51, 0xae, 0x4d, 0x62, 0x83, 0xb4, 0x69, 0x36, 0x31, 0xde, 0x8e,
            0x92, 0x91, 0xc8, 0xd6, 0x28, 0xad, 0x2e, 0x57, 0xe5, 0x74, 0x99, 0x30, 0xc6, 0x30,
            0x35, 0x55, 0x72, 0x7f, 0x0c, 0xed, 0x5b, 0x75, 0x68, 0x75, 0x51, 0xf8, 0x52, 0x52,
            0xeb, 0xc2, 0xcc, 0xd7, 0x38, 0xad, 0x3c, 0xb6, 0x23, 0x76, 0xf8, 0xd0, 0x37, 0xb7,
            0x73, 0x79, 0x07, 0x8a, 0x4a, 0x3e, 0x81, 0xce, 0xfc, 0x44, 0x9b, 0xbc, 0x0c, 0xf4,
            0x7f, 0x51, 0xae, 0x3b, 0x6a, 0xe5, 0x0d, 0x3c, 0x58, 0xf8, 0xbd, 0x98, 0x98, 0xa2,
            0xc9, 0x99, 0x44, 0x54, 0x3b, 0x1c, 0x4c, 0x7f, 0x7e, 0xba, 0x85, 0x31, 0x0f, 0x60,
            0x72, 0xdf, 0x70, 0x7d, 0xf1, 0x2b, 0xe4, 0xdd, 0x76, 0x27, 0x7d, 0x26, 0x58, 0xe8,
            0x50, 0x3b, 0x24, 0xd2, 0xce, 0xf3, 0xb7, 0x34, 0x93, 0xe6, 0xcd, 0x13, 0x82, 0x29,
            0xa6, 0x96, 0x01, 0xaf, 0xa9, 0xa8, 0xbf, 0x46, 0x65, 0xbb, 0x24, 0x2b, 0x3b, 0x89,
            0x1d, 0xfd, 0x4b, 0x90, 0x93, 0xf6, 0x00, 0xb0, 0x1f, 0x6d, 0x99, 0xdd, 0xb0, 0xc1,
            0x92, 0x75, 0x3a, 0xa6, 0xcd, 0x42, 0xaa, 0x38, 0x5d, 0xe6, 0x5d, 0xbd, 0x5d, 0x92,
            0x4f, 0x4b, 0x3c, 0x33, 0x7a, 0x6f, 0xc3, 0xc9, 0xc7, 0x06, 0x86, 0x4a, 0x5c, 0xe2,
            0xbe, 0xeb, 0x63, 0xf9, 0x16, 0x43, 0xd0, 0x56, 0xcc, 0x3e, 0xc5, 0xa5, 0x78, 0xca,
            0xd6, 0x0d, 0xd5, 0x78, 0xac, 0x5a, 0xea, 0x09, 0x68, 0xe9, 0x5a, 0x16, 0x3c, 0x83,
            0xf1, 0xbb, 0x34, 0x72, 0xc3, 0x85, 0xf2, 0x51, 0x64, 0x08, 0x74, 0x58, 0xc5, 0xc2,
            0xf1, 0xfc, 0x48, 0x55, 0x83, 0x8d, 0x87, 0x87, 0xf6, 0x0c, 0x35, 0xc4, 0x43, 0xe4,
            0x98, 0xdf, 0x63, 0x5f, 0xce, 0x8e, 0xac, 0x67, 0x65, 0x1c, 0xc2, 0xd8, 0xac, 0xb0,
            0xd9, 0xa2, 0xf5, 0xfd, 0x2f, 0xb5, 0xf2, 0xe5, 0x7e, 0x90, 0xc9, 0x5f, 0x8e, 0x76,
            0x48, 0x89, 0xb1, 0x30, 0x83, 0x94, 0x2f, 0x52, 0x7a, 0x00, 0x9b, 0xe0, 0xb2, 0x6c,
            0x98, 0xe0, 0x65, 0x50, 0x7d, 0xa1, 0x00, 0xa0, 0xba, 0x9b, 0x38, 0x5d, 0xaa, 0xca,
            0x9f, 0x57, 0x0f, 0x4f, 0x12, 0x01, 0x72, 0x87, 0xb6, 0xfb, 0xab, 0x23, 0xf1, 0x93,
            0xe8, 0x42, 0xa1, 0xfd, 0x23, 0x64, 0xd8, 0x0b, 0xc6, 0xaf, 0x76, 0x38, 0x13, 0xe2,
            0xe8, 0x76, 0x19, 0x5d, 0xdd, 0xe7, 0x7a, 0xe5, 0xf4, 0x5d, 0xe8, 0xf7, 0x98, 0x7b,
            0x88, 0x1f, 0xd6, 0x12, 0x0a, 0xbc, 0xa0, 0x6a, 0x5b, 0x26, 0x9c, 0x88, 0x7f, 0x0b,
            0xf5, 0x9f, 0x3d, 0x88, 0xf4, 0x9d, 0x5a, 0x76, 0xe9, 0x05, 0x30, 0x01, 0x27, 0x2a,
            0x30, 0x5d, 0xf5, 0x55, 0xa1, 0x79, 0xaf, 0xa0, 0x64, 0xf6, 0xad, 0x5a, 0x89, 0x12,
            0x56, 0xa1, 0xee, 0x33, 0x4a, 0x96, 0xb7, 0x4f, 0x43, 0xcf, 0x31, 0x00, 0xf5, 0x59,
            0xb7, 0xef, 0xea, 0x97, 0xce, 0x77, 0x0b, 0xdf, 0x11, 0xe3, 0xc2, 0xf4, 0x0f, 0x36,
            0xc0, 0xbf, 0xf2, 0x44, 0x69, 0x88, 0x82, 0x11, 0xac, 0xe0, 0x79, 0x82, 0x6e, 0x17,
            0xef, 0x72, 0x39, 0x08, 0xa4, 0xd9, 0x5a, 0x17, 0x29, 0x6f, 0xcb, 0xb0, 0x66, 0x51,
            0xd8, 0xe8, 0xa4, 0x29, 0xe1, 0x6c, 0x05, 0x5e, 0x92, 0x2f, 0x01, 0xfd, 0x70, 0x9c,
            0x78, 0xb2, 0xae, 0xdb, 0xb2, 0xbc, 0x1f, 0x0b, 0x75, 0x57, 0xca, 0xac, 0x87, 0x49,
            0x26, 0x88, 0x69, 0x90, 0x89, 0xd0, 0x0a, 0x16, 0x9d, 0xae, 0xf6, 0xc7, 0xd2, 0x32,
            0x5a, 0x96, 0x6d, 0x34, 0x54, 0xca, 0xb1, 0x09, 0x7a, 0xc2, 0xc1, 0xac, 0x17, 0x54,
            0x8d, 0xfe, 0x33, 0xac, 0xf7, 0xe7, 0xc4, 0xc1, 0x74, 0x39, 0xc2, 0x92, 0x88, 0x26,
            0x5e, 0x6d, 0x42, 0x6c, 0x5f, 0x7c, 0x4b, 0x1f, 0x72, 0x11, 0xbe, 0xfb, 0x36, 0xfb,
            0x85, 0xce, 0xd2, 0x19, 0x6a, 0xe7, 0x65, 0x6e, 0x76, 0x55, 0x96, 0x5a, 0x4e, 0x9e,
            0xdc, 0xa9, 0x60, 0x2b, 0x5c, 0x5d, 0x36, 0xca, 0xfb, 0x4f, 0x6b, 0xd9, 0x8d, 0xde,
            0x9f, 0xe0, 0x3c, 0xc6, 0xf4, 0xe4, 0xa3, 0x2a, 0x83, 0x33, 0xd0, 0x8b, 0x90, 0xe0,
            0x18, 0xa6, 0xa3, 0x08, 0x9b, 0x1d, 0xd2, 0x5b, 0x2d, 0x5b, 0x6b, 0xef, 0x3f, 0x7c,
            0xec, 0xbd, 0xe9, 0x43, 0xa9, 0xc0, 0x98, 0xfc, 0x46, 0x49, 0x8e, 0x99, 0x5a, 0xc9,
            0xa1, 0x9c, 0xdd, 0xae, 0x7a, 0xd7, 0x30, 0xed, 0xf3, 0x88, 0x47, 0xf5, 0x48, 0xde,
            0x2e, 0x79, 0x91, 0xeb, 0x35, 0x60, 0x1e, 0x1b, 0x09, 0x45, 0xfb, 0x87, 0x67, 0xb2,
            0x87, 0x94, 0x76, 0x72, 0x48, 0x7b, 0x3f, 0x28, 0x11, 0xdd, 0xe1, 0x07, 0x88, 0x08,
            0x75, 0x9f, 0x17, 0x6a, 0x9f, 0xa7, 0x22, 0x63, 0x59, 0x21, 0x61, 0xaa, 0xc2, 0x10,
            0xdf, 0x00, 0xfc, 0xef, 0xf7, 0x99, 0xc7, 0x26, 0xcc, 0x5f, 0x8a, 0x19, 0x0b, 0x4f,
            0x6c, 0x93, 0x61, 0x87, 0x2a, 0xf2, 0x99, 0x5d, 0xc8, 0x14, 0xbd, 0xa2, 0xa5, 0x8c,
            0x21, 0x5e, 0xc3, 0xd9, 0x08, 0xe5, 0xa3, 0x6d, 0xd0, 0x1c, 0xdf, 0xad, 0xb8, 0xc5,
            0xd3, 0xd7, 0xa6, 0xf7, 0xc4, 0x7c, 0xd3, 0xf2, 0x3b, 0x55, 0x34, 0x63, 0x1b, 0x64,
            0xb5, 0xf1, 0xf2, 0x73, 0x68, 0x6e, 0x99, 0x08, 0x2c, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xe9, 0x03, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00,
        ];
        let tag = block_on(poly1305_mac_async( &otk, message)).unwrap();
        let expected_tag = &[
            0x45, 0x6b, 0x78, 0xfc, 0x85, 0x68, 0xbd, 0x62, 0x07, 0x1e, 0x6b, 0x32, 0x9c, 0x23,
            0xfb, 0x50,
        ];
        assert_eq!(&tag as &[u8], expected_tag);
    }

    #[test]
    fn test_poly1305_mac_3() {
        let otk = [
            0x50, 0xd7, 0x07, 0xbc, 0xa8, 0xe5, 0x35, 0x3d, 0x3d, 0xb1, 0x01, 0xf6, 0x78, 0x10,
            0xb7, 0x3f, 0x7d, 0x92, 0x02, 0xd8, 0xe4, 0xbd, 0x11, 0x8f, 0xd7, 0xca, 0x44, 0x68,
            0x54, 0x56, 0xe6, 0x6f,
        ];
        let message: &[u8] = &[
            0x17, 0x03, 0x03, 0x05, 0xed, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0xde, 0x6c, 0xea, 0x98, 0x72, 0x1c, 0xb8, 0xfc, 0x60, 0xec, 0x26, 0xec,
            0x15, 0x50, 0x27, 0x0c, 0x43, 0x29, 0x6b, 0x4c, 0x9a, 0x67, 0x9e, 0xe1, 0x7b, 0x88,
            0xfd, 0x73, 0xae, 0xbf, 0xc8, 0x43, 0xd9, 0xcd, 0x74, 0x8c, 0x4e, 0xd2, 0xd9, 0x8d,
            0x01, 0x18, 0x63, 0xd9, 0x36, 0xef, 0x81, 0xf6, 0x7a, 0x7e, 0xf0, 0x3a, 0x8f, 0x27,
            0xac, 0x81, 0xf1, 0x8d, 0xee, 0xbd, 0x2c, 0xb9, 0xe7, 0x9a, 0xb0, 0x2c, 0xad, 0xe7,
            0x98, 0x9d, 0x16, 0x9d, 0x76, 0xda, 0x78, 0xac, 0x58, 0x26, 0x0b, 0x27, 0xd5, 0x3b,
            0x66, 0xa4, 0xab, 0x7c, 0x8d, 0x36, 0x2b, 0x9d, 0x12, 0xe3, 0x30, 0x11, 0x9c, 0x49,
            0xa6, 0xbc, 0x0a, 0xae, 0x31, 0x7d, 0x6f, 0xa8, 0x24, 0x5c, 0x9f, 0xe7, 0xd6, 0x65,
            0x91, 0x72, 0x89, 0xb4, 0xbc, 0x19, 0x16, 0xe2, 0x3b, 0xe4, 0xcb, 0x5d, 0xb1, 0x4a,
            0x3b, 0x57, 0x8f, 0x22, 0x2a, 0x6d, 0x87, 0x62, 0x9a, 0xf9, 0x3f, 0x0c, 0x09, 0x7f,
            0x0f, 0x80, 0x53, 0x9d, 0x4e, 0x15, 0xb9, 0x29, 0xd5, 0x75, 0x97, 0x9e, 0x01, 0xa5,
            0x7c, 0x8a, 0x0b, 0xf2, 0xf2, 0xfb, 0x7d, 0xcd, 0xa5, 0x0d, 0x76, 0x02, 0xd6, 0x6c,
            0x43, 0x0b, 0xf2, 0x74, 0xc1, 0x75, 0xc2, 0xc3, 0xe9, 0x25, 0xce, 0xf8, 0x0d, 0xc6,
            0x0a, 0xd2, 0xe4, 0xef, 0xa3, 0xb7, 0xed, 0x92, 0x58, 0x51, 0xfc, 0xc6, 0x0d, 0x0e,
            0x8f, 0xe1, 0xbe, 0xde, 0x6c, 0x01, 0xb5, 0x03, 0x4f, 0xbb, 0x47, 0x76, 0xf2, 0x04,
            0x44, 0xb5, 0x93, 0x83, 0x58, 0xad, 0x06, 0x3e, 0x95, 0x39, 0xbc, 0x16, 0xc9, 0xe7,
            0x17, 0x45, 0xce, 0xc0, 0x79, 0x0f, 0x50, 0x74, 0x8d, 0x5a, 0xf6, 0xc4, 0xe2, 0xfd,
            0x97, 0xf2, 0x49, 0x86, 0x75, 0x93, 0x8d, 0x9e, 0xbc, 0x23, 0x04, 0x0e, 0x76, 0x2a,
            0xf1, 0x66, 0xbd, 0xef, 0xe8, 0xd0, 0xc1, 0xcb, 0xd6, 0x8f, 0x21, 0x6f, 0xfc, 0xd4,
            0xd2, 0xed, 0x7b, 0xc4, 0x3a, 0x5d, 0xe7, 0x3c, 0xca, 0xa4, 0x56, 0x18, 0x65, 0x42,
            0x5a, 0x78, 0xf4, 0x4a, 0xe1, 0x31, 0xfe, 0x68, 0xfd, 0xd5, 0x85, 0x10, 0xa6, 0x88,
            0x45, 0x99, 0xa5, 0x95, 0xd3, 0x3a, 0xe4, 0x6b, 0xd3, 0x03, 0x84, 0xdc, 0xd2, 0x56,
            0x01, 0x5c, 0xfc, 0x52, 0x1f, 0x47, 0xca, 0x3a, 0xf6, 0x49, 0xf6, 0x24, 0xc8, 0x4d,
            0xfb, 0x69, 0x06, 0x00, 0xd5, 0x12, 0x6b, 0xcb, 0x98, 0xab, 0x51, 0xe5, 0xcc, 0xbf,
            0x4d, 0xe9, 0x60, 0x80, 0x8d, 0x41, 0x64, 0x95, 0x36, 0x94, 0x65, 0x4a, 0x04, 0x58,
            0xc3, 0xf3, 0x43, 0x54, 0xce, 0x11, 0xe3, 0x95, 0xdb, 0x95, 0xfe, 0x51, 0x08, 0x51,
            0x07, 0x37, 0xef, 0x50, 0xca, 0x20, 0x39, 0x2d, 0xce, 0xed, 0x4e, 0x59, 0x68, 0x38,
            0x8e, 0x3b, 0xb1, 0xde, 0x21, 0x56, 0xe8, 0xb0, 0x81, 0xb3, 0xcc, 0x66, 0x94, 0x1d,
            0xeb, 0x40, 0xe6, 0xb5, 0x2d, 0x79, 0x47, 0x35, 0x4e, 0x85, 0x45, 0xb0, 0x62, 0x4b,
            0x01, 0xb7, 0xe4, 0x0b, 0x8f, 0x77, 0x5a, 0x39, 0x32, 0x58, 0xd1, 0xd4, 0xd1, 0xe7,
            0xc8, 0x18, 0xd0, 0x75, 0x44, 0x7a, 0x43, 0x41, 0xbe, 0x0e, 0xca, 0xf5, 0x38, 0x9f,
            0xdd, 0x1b, 0x47, 0x62, 0x30, 0xee, 0xee, 0x16, 0x7b, 0x32, 0xbc, 0xe3, 0x55, 0x70,
            0x0a, 0xcf, 0xe4, 0xf9, 0x65, 0x01, 0xf4, 0x9e, 0x4a, 0x82, 0x68, 0xe0, 0x62, 0x1a,
            0xac, 0x14, 0x3c, 0x1b, 0x94, 0x0e, 0xd3, 0x85, 0xa2, 0x1d, 0x61, 0x08, 0xad, 0x5a,
            0x9c, 0x5e, 0xdc, 0x81, 0x9c, 0x7b, 0xf2, 0xe4, 0x7f, 0x25, 0x53, 0x47, 0x31, 0x66,
            0x4d, 0xbd, 0x80, 0x36, 0x6f, 0xa1, 0x33, 0x80, 0x05, 0x5b, 0x79, 0xe0, 0x86, 0x5f,
            0x3c, 0x08, 0xe7, 0x5e, 0x02, 0x7f, 0x42, 0x92, 0xe3, 0x31, 0xf0, 0x6f, 0xbf, 0x91,
            0x54, 0x12, 0xa9, 0x6e, 0xe4, 0x48, 0xed, 0x75, 0x78, 0x8f, 0x66, 0x59, 0x00, 0xcd,
            0x0a, 0x5a, 0xeb, 0x62, 0xe7, 0x82, 0x61, 0x21, 0xed, 0xc0, 0xd5, 0xc5, 0x08, 0xf6,
            0x9a, 0x4c, 0xd0, 0x01, 0x0f, 0xe0, 0xe2, 0x3f, 0xd2, 0xf8, 0x15, 0xc9, 0x91, 0x74,
            0xec, 0x9a, 0x36, 0x73, 0x71, 0x1a, 0xb4, 0x8c, 0x3a, 0xe3, 0x31, 0xaf, 0xdd, 0xb8,
            0xc2, 0xef, 0x3b, 0x61, 0xe3, 0x6f, 0x1f, 0xea, 0x28, 0xb3, 0x38, 0x77, 0x03, 0x3d,
            0x20, 0xa9, 0x79, 0x68, 0x27, 0x68, 0x41, 0x18, 0xea, 0x58, 0xaf, 0xc5, 0x38, 0xae,
            0xca, 0x56, 0x81, 0x55, 0xec, 0xa6, 0x59, 0xa0, 0xf0, 0x7a, 0x8d, 0xf2, 0x05, 0x17,
            0xd0, 0x93, 0x47, 0x1f, 0x6a, 0x77, 0xc6, 0x60, 0xdb, 0xb5, 0x60, 0x38, 0xe1, 0xd9,
            0xf3, 0xc3, 0xae, 0x0a, 0x16, 0x5c, 0x46, 0xd9, 0xdf, 0xf6, 0x8a, 0xa1, 0x6a, 0x09,
            0x89, 0xac, 0xaa, 0x53, 0xa0, 0x4c, 0x0e, 0x6b, 0x3b, 0x0c, 0x9c, 0x6d, 0xaa, 0xb4,
            0xef, 0x09, 0x00, 0x63, 0x14, 0xa1, 0xda, 0xef, 0x4a, 0x0b, 0xe9, 0xd6, 0x22, 0x51,
            0xd5, 0x9b, 0x71, 0xca, 0xd9, 0xbd, 0x43, 0x9b, 0x1e, 0x8b, 0x45, 0x20, 0xb0, 0x94,
            0x4a, 0x81, 0x62, 0xc2, 0x0d, 0x48, 0x89, 0xd2, 0x33, 0xf8, 0xed, 0xa8, 0x7d, 0xc1,
            0x10, 0x02, 0x57, 0x83, 0x4a, 0x32, 0x1e, 0x35, 0xf3, 0xf4, 0x6c, 0xb3, 0x01, 0x47,
            0x3d, 0xe4, 0xb4, 0xc1, 0x7a, 0xfe, 0x19, 0x0f, 0x3a, 0x8c, 0x6f, 0xa7, 0x1d, 0xf0,
            0x32, 0x80, 0x7f, 0x92, 0x4c, 0x49, 0xc4, 0xb0, 0x41, 0x08, 0xb2, 0x2f, 0x22, 0x3f,
            0x6d, 0xcc, 0xa3, 0xd0, 0x3a, 0xe7, 0x11, 0x14, 0x5a, 0x57, 0x3f, 0xb3, 0xc8, 0x2b,
            0x79, 0xe9, 0x53, 0x94, 0x34, 0x74, 0x26, 0x07, 0x85, 0x06, 0x96, 0x4c, 0x93, 0x63,
            0x1e, 0x11, 0x18, 0xe8, 0x86, 0x19, 0x2e, 0x82, 0xbe, 0x17, 0x6b, 0x37, 0xba, 0x6d,
            0x1a, 0xa0, 0x68, 0x20, 0x54, 0x12, 0xff, 0x88, 0xbc, 0x4b, 0x87, 0x45, 0x9d, 0x03,
            0x06, 0x11, 0x57, 0x4d, 0x25, 0x41, 0x3a, 0x5f, 0x11, 0x21, 0x2f, 0xeb, 0xd6, 0xdc,
            0x34, 0xda, 0xfd, 0x4c, 0xe0, 0xe9, 0x6c, 0xce, 0x35, 0xed, 0x87, 0xf0, 0x6c, 0xda,
            0xb0, 0x77, 0x3a, 0x24, 0x33, 0xea, 0x88, 0xaf, 0x15, 0x98, 0xef, 0xeb, 0xab, 0xc1,
            0xc1, 0xf3, 0x8b, 0x9f, 0xbe, 0xdb, 0x34, 0x29, 0x14, 0xf5, 0x9d, 0x58, 0xd1, 0x53,
            0x4c, 0xbb, 0xc0, 0x1f, 0xc1, 0x7a, 0x2d, 0x94, 0x2a, 0x86, 0xcc, 0x24, 0x95, 0x42,
            0x69, 0xea, 0x72, 0x22, 0x1d, 0xbd, 0x19, 0xd7, 0x5e, 0xb3, 0xd0, 0x5f, 0xb3, 0xa9,
            0x4d, 0x52, 0xa0, 0x9a, 0xb0, 0xe3, 0xde, 0x14, 0x2d, 0xf1, 0x3f, 0x82, 0x82, 0x39,
            0x9f, 0xee, 0x78, 0xa8, 0xec, 0x33, 0x0c, 0x01, 0x9a, 0xdf, 0xcf, 0xb3, 0x54, 0x02,
            0x2e, 0xcc, 0x58, 0x0b, 0xfd, 0x0e, 0xe3, 0xac, 0x12, 0x0f, 0x8b, 0x87, 0x0a, 0xad,
            0x1e, 0x4b, 0x1d, 0x45, 0x3e, 0x6c, 0x4c, 0x7d, 0xff, 0x55, 0xb4, 0x81, 0xaa, 0x0b,
            0xf0, 0x75, 0x32, 0xa8, 0x32, 0x4d, 0x11, 0xf2, 0xb6, 0x58, 0x42, 0xac, 0x37, 0x6b,
            0x78, 0xe3, 0x93, 0x3a, 0xaf, 0x26, 0x59, 0x3c, 0xa2, 0x81, 0xab, 0xbc, 0x2c, 0x42,
            0x87, 0xa7, 0x41, 0x55, 0xb1, 0xe2, 0xa3, 0xf1, 0x0a, 0xa8, 0xd8, 0x11, 0xe8, 0xd7,
            0xb8, 0x03, 0x44, 0xab, 0xa6, 0x66, 0x98, 0x3c, 0x90, 0x17, 0x88, 0xdd, 0xe7, 0x9c,
            0x1a, 0x27, 0xba, 0xce, 0x04, 0x3d, 0x34, 0x74, 0xd1, 0xe1, 0x5b, 0x41, 0x5e, 0x2c,
            0x75, 0x30, 0x03, 0xf6, 0x85, 0x17, 0xbb, 0xb8, 0xfb, 0xb7, 0x7a, 0xf9, 0xb7, 0xc2,
            0x51, 0x29, 0xe5, 0xc5, 0xf8, 0x0b, 0x86, 0x60, 0x7f, 0x7a, 0x81, 0xe6, 0x0b, 0x23,
            0xdf, 0xd2, 0x60, 0x1c, 0xbc, 0xaf, 0x2e, 0x6f, 0x1d, 0xd5, 0x81, 0x5e, 0x0e, 0xd0,
            0x07, 0x54, 0x81, 0x29, 0x30, 0xa0, 0x28, 0xa5, 0xe8, 0x48, 0x9d, 0xea, 0x1d, 0xc5,
            0x60, 0xff, 0xc3, 0xac, 0x1b, 0x0b, 0xa2, 0xbc, 0x14, 0x63, 0x2b, 0x52, 0xea, 0x5d,
            0x8c, 0x48, 0xdb, 0x63, 0x72, 0x4b, 0x1b, 0x2c, 0x27, 0xfd, 0x0d, 0x51, 0xa4, 0x28,
            0xec, 0xe2, 0xc2, 0x21, 0xbe, 0x51, 0x77, 0x58, 0x5f, 0x45, 0x81, 0x7e, 0x62, 0x4a,
            0x07, 0x5f, 0xd2, 0x2d, 0xa2, 0x4f, 0x18, 0x74, 0x63, 0x1a, 0xae, 0x43, 0x09, 0x5d,
            0xfb, 0x1e, 0x5d, 0xfb, 0x5a, 0xff, 0x10, 0x41, 0x92, 0xb9, 0xd4, 0x26, 0x01, 0x1c,
            0x45, 0xd1, 0x5c, 0xb1, 0x62, 0x08, 0xad, 0x60, 0x6e, 0xce, 0xdf, 0x27, 0x49, 0x2f,
            0xb2, 0x00, 0x59, 0x5b, 0x36, 0x0f, 0xe9, 0xdf, 0xc2, 0xd1, 0xc4, 0x32, 0x84, 0x55,
            0x07, 0x22, 0x5d, 0x91, 0x53, 0x9f, 0xef, 0x13, 0xe6, 0x07, 0xb8, 0x85, 0xbb, 0x9f,
            0xc7, 0xda, 0x09, 0x3a, 0x68, 0x8d, 0xc9, 0x9f, 0xcd, 0x76, 0xdb, 0x73, 0x6b, 0x57,
            0x36, 0x3a, 0xbf, 0xc5, 0x97, 0xcb, 0x85, 0xd1, 0x25, 0xc4, 0x10, 0x07, 0x0c, 0x2c,
            0x6f, 0x1e, 0x11, 0x46, 0xc8, 0xbb, 0x10, 0x95, 0x35, 0x1e, 0x39, 0x27, 0x05, 0x6e,
            0x91, 0x0d, 0xb5, 0xa6, 0x66, 0xe4, 0xcf, 0xa5, 0xac, 0x4d, 0x2b, 0x48, 0xfd, 0x2d,
            0x94, 0x4a, 0x84, 0xde, 0xf6, 0x67, 0x63, 0xa5, 0x4a, 0x53, 0x1d, 0x74, 0x6e, 0xe8,
            0xf0, 0xc5, 0x9c, 0x87, 0xec, 0x30, 0xa9, 0x34, 0x3d, 0x89, 0x52, 0x37, 0x84, 0xa9,
            0x20, 0x4e, 0xed, 0x89, 0xaa, 0xb3, 0x2e, 0xec, 0x03, 0x38, 0x33, 0xe1, 0x03, 0x35,
            0x0a, 0xc7, 0xc0, 0x4c, 0x43, 0x36, 0x8e, 0x38, 0xa8, 0xe9, 0xbc, 0x03, 0x42, 0x86,
            0xaf, 0x14, 0xda, 0x1a, 0x20, 0xca, 0xc6, 0xdc, 0xb8, 0xb5, 0xf7, 0x9e, 0x39, 0x7c,
            0x9a, 0x43, 0xee, 0xbb, 0x53, 0xe0, 0x6d, 0xa0, 0xef, 0xa7, 0x00, 0xf1, 0x48, 0xc4,
            0x7d, 0xb2, 0x60, 0xb2, 0x14, 0xaf, 0x7f, 0x24, 0x83, 0x81, 0x40, 0xff, 0xc2, 0x1a,
            0x0d, 0xe8, 0xaf, 0x8c, 0x6d, 0xdf, 0x6d, 0xfc, 0x90, 0x2a, 0x92, 0xb4, 0xd5, 0x21,
            0xe5, 0xb4, 0xf2, 0x93, 0xb5, 0x2f, 0x64, 0x45, 0x95, 0xdb, 0x01, 0x87, 0x21, 0x1d,
            0xa8, 0x44, 0xcb, 0x26, 0x14, 0x1d, 0xd5, 0x1b, 0xd3, 0x7f, 0xf6, 0x11, 0x4e, 0x01,
            0xa8, 0xa3, 0xb8, 0x90, 0xb3, 0x05, 0xf6, 0xc1, 0x00, 0x0d, 0xd5, 0x5a, 0x48, 0xe9,
            0x7f, 0x19, 0x43, 0xc4, 0x8b, 0xbb, 0x0b, 0xb2, 0xd0, 0x3c, 0x7f, 0x0d, 0x6c, 0xbd,
            0xbe, 0xba, 0xee, 0x40, 0x04, 0x93, 0xf7, 0x1f, 0x97, 0xa9, 0x9b, 0xef, 0x0e, 0x18,
            0x0b, 0x82, 0xfe, 0xe5, 0x7b, 0x0a, 0xc5, 0x1b, 0x02, 0x89, 0x4e, 0x6a, 0x62, 0x69,
            0x1f, 0x95, 0xa3, 0xb0, 0xeb, 0x87, 0x11, 0xa3, 0x5f, 0xa4, 0x33, 0xbd, 0xeb, 0xd1,
            0xc2, 0x91, 0x0c, 0xf8, 0x7f, 0x73, 0xa7, 0x48, 0xdd, 0x1c, 0x32, 0x69, 0x1b, 0xbc,
            0xb8, 0x6d, 0x91, 0xc3, 0xb9, 0x59, 0x1b, 0xf1, 0x0d, 0xbe, 0x20, 0x1f, 0xc3, 0x37,
            0x91, 0x8c, 0x15, 0xeb, 0xbb, 0xc4, 0xaa, 0xc5, 0x8a, 0xa3, 0xf3, 0x30, 0xad, 0xab,
            0x48, 0x5a, 0xb9, 0x4d, 0x08, 0xcc, 0x36, 0x7e, 0x8b, 0x01, 0x0b, 0x01, 0xed, 0xfd,
            0xaa, 0x17, 0x50, 0x4f, 0x28, 0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0xdd, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        ];
        let tag = block_on(
            poly1305_mac_async(&otk, message)
        ).unwrap();
        let expected_tag = &[
            0x78, 0xfb, 0xe0, 0x05, 0xdb, 0xff, 0x31, 0xf6, 0xdf, 0xdf, 0xe4, 0x58, 0x7b, 0x4d,
            0xbe, 0x8e,
        ];
        assert_eq!(&tag as &[u8], expected_tag);
    }

    #[test]
    fn test_poly1305_mod() {
        let a: [u32; 5] = [0x2dde68f6, 0x672041f6, 0xf0a01508, 0x1ed7f726, 0x04];
        assert_eq!(
            poly1305_mod(a),
            [0x2dde68fb, 0x672041f6, 0xf0a01508, 0x1ed7f726, 0x0]
        );

        let a: [u32; 5] = [0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0x03];
        assert_eq!(poly1305_mod(a), [0x4, 0, 0, 0, 0]);

        let a: [u32; 5] = [0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0x04];
        assert_eq!(poly1305_mod(a), [0x4, 0, 0, 0, 0x1]);

        let a: [u32; 5] = [0xfffffffa, 0xffffffff, 0xffffffff, 0xffffffff, 0x03];
        assert_eq!(
            poly1305_mod(a),
            [0xfffffffa, 0xffffffff, 0xffffffff, 0xffffffff, 0x3]
        );

        let a: [u32; 5] = [0xfffffffb, 0xffffffff, 0xffffffff, 0xffffffff, 0x03];
        assert_eq!(poly1305_mod(a), [0, 0, 0, 0, 0]);

        let a: [u32; 5] = [0xfffffffc, 0xffffffff, 0xffffffff, 0xffffffff, 0x03];
        assert_eq!(poly1305_mod(a), [1, 0, 0, 0, 0]);
    }

    #[test]
    fn test_cha_cha_20_encrypt_empty() {
        let key: [u8; 32] = [0; 32];
        let nonce: [u8; 12] = [0; 12];
        let plaintext: &[u8] = &[];
        let mut result = vec![];
        block_on(
            cha_cha_20_encrypt(&key, 1, &nonce, plaintext, &mut result)
        ).unwrap();
        assert_eq!(result, &[]);
    }

    #[test]
    fn test_cha_cha_20_encrypt_large() {
        let key: [u8; 32] = [0; 32];
        let nonce: [u8; 12] = [0; 12];
        let plaintext: Vec<u8> = vec![0; 1024]; // 16 blocks
        let mut result = vec![];
        block_on(
            cha_cha_20_encrypt(&key, 1, &nonce, plaintext.as_slice(), &mut result)
        ).unwrap();
        assert_eq!(result.len(), 1024);
    }

    #[test]
    fn test_poly1305_mac_async_small_chunks() {
        let key: [u8; 32] = [0; 32];
        let mut message: &[u8] = &[0; 32];
        let tag = block_on(
            poly1305_mac_async(&key, &mut message)
        ).unwrap();
        let expected:&[u8] = &[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
        assert_eq!(&tag, expected);
    }

    #[test]
    fn test_cha_cha_20_aead_decrypt_tampered() {
        let key: [u8; 32] = [0; 32];
        let nonce: [u8; 12] = [0; 12];
        let plaintext: &[u8] = b"test";
        let aad: &[u8] = b"aad";
        let mut ciphertext = vec![];
        let expected_tag = block_on(
            cha_cha_20_aead_encrypt(aad, &key, nonce, plaintext, &mut ciphertext)
        ).unwrap();
        ciphertext[0] ^= 1; // Tamper
        let mut plain_text = vec![];
        let result = block_on(
            cha_cha_20_aead_decrypt_verify(aad, &key, nonce, ciphertext.as_slice(), &mut plain_text, expected_tag)
        );
        assert!(matches!(result, Err(err) if err.kind() == io::ErrorKind::InvalidData));
    }

    #[test]
    fn test_cha_cha_20_aead_decrypt_wrong_tag() {
        let key: [u8; 32] = [0; 32];
        let nonce: [u8; 12] = [0; 12];
        let plaintext: &[u8] = b"test";
        let aad: &[u8] = b"aad";
        let mut ciphertext = vec![];
        let tag = block_on(
            cha_cha_20_aead_encrypt(aad, &key, nonce, plaintext, &mut ciphertext)
        ).unwrap();
        let mut wrong_tag = tag;
        wrong_tag[0] ^= 1;
        let mut plain_text = vec![];
        let result = block_on(
            cha_cha_20_aead_decrypt_verify(aad, &key, nonce, 
                ciphertext.as_slice(), &mut plain_text, wrong_tag)
        );
        assert!(matches!(result, Err(err) if err.kind() == io::ErrorKind::InvalidData));
    }

    #[test]
    fn test_cha_cha_20_encrypt_reader_error() {
        struct FailingReader;
        impl AsyncRead for FailingReader {
            fn poll_read(self: std::pin::Pin<&mut Self>, _cx: &mut std::task::Context<'_>, _buf: &mut [u8]) -> std::task::Poll<io::Result<usize>> {
                std::task::Poll::Ready(Err(io::Error::new(io::ErrorKind::Other, "read error")))
            }
        }
        let key: [u8; 32] = [0; 32];
        let nonce: [u8; 12] = [0; 12];
        let mut cipher1 = vec![];
        let result = block_on(
            cha_cha_20_encrypt(&key, 1, &nonce, FailingReader, &mut cipher1),
        );
        assert!(result.is_err());
    }

    #[test]
    fn test_cha_cha_20_key_sensitivity() {
        let key1: [u8; 32] = [0; 32];
        let key2: [u8; 32] = [1; 32];
        let nonce: [u8; 12] = [0; 12];
        let plaintext: &[u8] = b"test";
        let mut cipher1 = vec![];
        block_on(
            cha_cha_20_encrypt(&key1, 1, &nonce, plaintext, &mut cipher1)
        ).unwrap();
        let mut cipher2 = vec![];
        block_on(
            cha_cha_20_encrypt(&key2, 1, &nonce, plaintext, &mut cipher2)
        ).unwrap();
        assert_ne!(cipher1, cipher2);
    }

    #[test]
    fn test_cha_cha_20_nonce_reuse() {
        let key: [u8; 32] = [0; 32];
        let nonce1: [u8; 12] = [0; 12];
        let nonce2: [u8; 12] = [1; 12];
        let block1 = cha_cha_20_block(&key, 1, &nonce1);
        let block2 = cha_cha_20_block(&key, 1, &nonce2);
        assert_ne!(block1, block2);
    }

    #[test]
    fn test_cha_cha_20_block_counter_zero() {
        let key: [u8; 32] = [
            0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
            0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
            0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
            0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
        ];
        let nonce: [u8; 12] = [0x00, 0x00, 0x00, 0x09, 0x00, 0x00, 0x00, 0x4a, 0x00, 0x00, 0x00, 0x00];
        let block = cha_cha_20_block(&key, 0, &nonce);
        let expected: [u8; 64] = [
            138, 220, 145, 253, 159, 244, 240, 245, 27, 15, 173, 80, 255, 21, 214, 55,
            228, 14, 253, 162, 6, 204, 82, 199, 131, 167, 66, 0, 80, 60, 21, 130,
            205, 152, 51, 54, 125, 10, 84, 213, 125, 60, 158, 153, 143, 73, 14, 230,
            156, 163, 76, 31, 249, 233, 57, 167, 85, 132, 197, 45, 105, 10, 53, 212
        ];
        assert_eq!(block, expected);
    }

    #[test]
    fn test_cha_cha_20_encrypt_counter_max() {
        let key: [u8; 32] = [
            0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
            0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
            0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
            0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
        ];
        let nonce: [u8; 12] = [0x00, 0x00, 0x00, 0x09, 0x00, 0x00, 0x00, 0x4a, 0x00, 0x00, 0x00, 0x00];
        let plaintext: [u8; 64] = [0; 64];
        let mut result = vec![];
        block_on(
            cha_cha_20_encrypt(&key, u32::MAX, &nonce, &plaintext[..], &mut result)
        ).unwrap();
        let expected: [u8; 64] = [
            255, 41, 65, 184, 215, 64, 246, 203, 181, 9, 54, 191, 153, 126, 189, 82,
            24, 203, 16, 141, 197, 63, 65, 198, 72, 65, 208, 33, 129, 103, 67, 12,
            160, 59, 119, 12, 167, 76, 203, 100, 42, 40, 25, 77, 29, 237, 210, 237,
            19, 21, 30, 37, 236, 93, 127, 174, 182, 208, 96, 191, 183, 230, 177, 70
        ];
        assert_eq!(result, expected);
    }

    #[test]
    fn test_poly1305_mac_empty() {
        let key: [u8; 32] = [
            0x85, 0xd6, 0xbe, 0x78, 0x57, 0x55, 0x6d, 0x33,
            0x7f, 0x44, 0x52, 0xfe, 0x42, 0xd5, 0x06, 0xa8,
            0x01, 0x03, 0x80, 0x8a, 0xfb, 0x0d, 0xb2, 0xfd,
            0x4a, 0xbf, 0xf6, 0xaf, 0x41, 0x49, 0xf5, 0x1b,
        ];
        let message:&[u8] = &[];
        let tag = block_on(
            poly1305_mac_async(&key, message)
        ).unwrap();
        let expected: [u8; 16] = [1, 3, 128, 138, 251, 13, 178, 253, 74, 191, 246, 175, 65, 73, 245, 27];
        assert_eq!(tag, expected);
    }

    #[test]
    fn test_poly1305_mac_16_bytes() {
        let key: [u8; 32] = [
            0x85, 0xd6, 0xbe, 0x78, 0x57, 0x55, 0x6d, 0x33,
            0x7f, 0x44, 0x52, 0xfe, 0x42, 0xd5, 0x06, 0xa8,
            0x01, 0x03, 0x80, 0x8a, 0xfb, 0x0d, 0xb2, 0xfd,
            0x4a, 0xbf, 0xf6, 0xaf, 0x41, 0x49, 0xf5, 0x1b,
        ];
        let message:&[u8] = &[
            0x43, 0x72, 0x79, 0x70, 0x74, 0x6f, 0x67, 0x72,
            0x61, 0x70, 0x68, 0x69, 0x63, 0x20, 0x46, 0x6f,
        ];
        let tag = block_on(
            poly1305_mac_async(&key, message)
        ).unwrap();
        let expected: [u8; 16] = [253, 134, 28, 113, 132, 249, 143, 69, 220, 109, 91, 77, 198, 192, 129, 228];
        assert_eq!(tag, expected);
    }

    #[test]
    fn test_cha_cha_20_aead_encrypt_empty() {
        let key: [u8; 32] = [
            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: [u8; 12] = [0x07, 0x00, 0x00, 0x00, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47];
        let plaintext: [u8; 0] = [];
        let aad: [u8; 0] = [];
        let mut ciphertext = vec![];
        let tag = block_on(
            cha_cha_20_aead_encrypt(&aad, &key, nonce, &plaintext[..], &mut ciphertext)
        ).unwrap();
        let expected_tag: [u8; 16] = [
            160, 120, 77, 122, 71, 22, 243, 254, 180, 246, 78, 127, 75, 57, 191, 4
        ];
        assert_eq!(ciphertext, &[]);
        assert_eq!(tag, expected_tag);
    }

    #[test]
    fn test_cha_cha_20_aead_encrypt_aad_16_bytes() {
        let key: [u8; 32] = [
            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: [u8; 12] = [0x07, 0x00, 0x00, 0x00, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47];
        let plaintext: [u8; 4] = [0x74, 0x65, 0x73, 0x74]; // "test"
        let aad: [u8; 16] = [
            0x50, 0x51, 0x52, 0x53, 0xc0, 0xc1, 0xc2, 0xc3,
            0xc4, 0xc5, 0xc6, 0xc7, 0x00, 0x00, 0x00, 0x00,
        ];
        let mut ciphertext = vec![];
        let tag = block_on(
            cha_cha_20_aead_encrypt(&aad, &key, nonce, &plaintext[..], &mut ciphertext)
        ).unwrap();
        let expected_ciphertext: [u8; 4] = [0xeb, 0x1e, 0x9a, 0x29];
        let expected_tag: [u8; 16] = [105, 124, 51, 142, 40, 75, 123, 86, 47, 48, 217, 240, 118, 71, 195, 224];
        assert_eq!(ciphertext, expected_ciphertext);
        assert_eq!(tag, expected_tag);
    }

    #[test]
    fn test_cha_cha_20_encrypt_small_chunks() {
        let key: [u8; 32] = [
            0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
            0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
            0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
            0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
        ];
        let nonce: [u8; 12] = [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x4a, 0x00, 0x00, 0x00, 0x00];
        let plaintext: &[u8] = b"test message";
        let mut result = vec![];
        block_on(
            cha_cha_20_encrypt(&key, 1, &nonce, plaintext, &mut result)
        ).unwrap();
        let expected: [u8; 12] = [86, 42, 34, 135, 96, 118, 188, 146, 92, 191, 64, 10];
        assert_eq!(&result, &expected[..]);
    }
}