//! `crypto_box_curve25519xsalsa20poly1305` , a particular
//! combination of Curve25519, Salsa20, and Poly1305 specified in
//! [Cryptography in `NaCl`](http://nacl.cr.yp.to/valid.html).
//!
//! This function is conjectured to meet the standard notions of privacy and
//! third-party unforgeability.

use ffi;
use randombytes::randombytes_into;

/// Number of bytes in a `PublicKey`.
pub const PUBLICKEYBYTES: usize =
    ffi::crypto_box_curve25519xsalsa20poly1305_PUBLICKEYBYTES as usize;

/// Number of bytes in a `SecretKey`.
pub const SECRETKEYBYTES: usize =
    ffi::crypto_box_curve25519xsalsa20poly1305_SECRETKEYBYTES as usize;

/// Number of bytes in a `Nonce`.
pub const NONCEBYTES: usize = ffi::crypto_box_curve25519xsalsa20poly1305_NONCEBYTES as usize;

/// Number of bytes in a `PrecomputedKey`.
pub const PRECOMPUTEDKEYBYTES: usize =
    ffi::crypto_box_curve25519xsalsa20poly1305_BEFORENMBYTES as usize;

/// Number of bytes in the authenticator tag of an encrypted message
/// i.e. the number of bytes by which the ciphertext is larger than the
/// plaintext.
pub const MACBYTES: usize = ffi::crypto_box_curve25519xsalsa20poly1305_MACBYTES as usize;

new_type! {
    /// `SecretKey` for asymmetric authenticated encryption
    ///
    /// When a `SecretKey` goes out of scope its contents
    /// will be zeroed out
    secret SecretKey(SECRETKEYBYTES);
}

new_type! {
    /// `PublicKey` for asymmetric authenticated encryption
    public PublicKey(PUBLICKEYBYTES);
}

impl SecretKey {
    /// `public_key()` computes the corresponding public key for a given secret key
    pub fn public_key(&self) -> PublicKey {
        unsafe {
            let mut pk = [0u8; PUBLICKEYBYTES];
            let _ = ffi::crypto_scalarmult_base(pk.as_mut_ptr(), self.0.as_ptr());
            PublicKey(pk)
        }
    }
}

new_type! {
    /// Authentication `Tag` for the detached encryption mode
    ///
    /// In the combined mode, the tag occupies the first MACBYTES bytes of the ciphertext.
    public Tag(MACBYTES);
}

new_type! {
    /// `Nonce` for asymmetric authenticated encryption
    nonce Nonce(NONCEBYTES);
}

/// `gen_keypair()` randomly generates a secret key and a corresponding public key.
///
/// THREAD SAFETY: `gen_keypair()` is thread-safe provided that you have
/// called `rust_sodium::init()` once before using any other function
/// from `rust_sodium`.
pub fn gen_keypair() -> (PublicKey, SecretKey) {
    unsafe {
        let mut pk = [0u8; PUBLICKEYBYTES];
        let mut sk = [0u8; SECRETKEYBYTES];
        let _todo_use_result =
            ffi::crypto_box_curve25519xsalsa20poly1305_keypair(pk.as_mut_ptr(), sk.as_mut_ptr());
        (PublicKey(pk), SecretKey(sk))
    }
}

/// `gen_nonce()` randomly generates a nonce
///
/// THREAD SAFETY: `gen_nonce()` is thread-safe provided that you have
/// called `rust_sodium::init()` once before using any other function
/// from `rust_sodium`.
pub fn gen_nonce() -> Nonce {
    let mut n = [0; NONCEBYTES];
    randombytes_into(&mut n);
    Nonce(n)
}

/// `seal()` encrypts and authenticates a message `m` using the senders secret key `sk`,
/// the receivers public key `pk` and a nonce `n`. It returns a ciphertext `c`.
pub fn seal(
    m: &[u8],
    &Nonce(ref n): &Nonce,
    &PublicKey(ref pk): &PublicKey,
    &SecretKey(ref sk): &SecretKey,
) -> Vec<u8> {
    let clen = m.len() + MACBYTES;
    let mut c = Vec::with_capacity(clen);
    unsafe {
        c.set_len(clen);
        let _ = ffi::crypto_box_easy(
            c.as_mut_ptr(),
            m.as_ptr(),
            m.len() as u64,
            n.as_ptr(),
            pk.as_ptr(),
            sk.as_ptr(),
        );
    }
    c
}

/// `seal_detached()` encrypts and authenticates a message `m` using the senders secret key `sk`,
/// the receivers public key `pk` and a nonce `n`. `m` is encrypted in place, so after this
/// function returns it will contain the ciphertext. The detached authentication tag is returned by
/// value.
pub fn seal_detached(
    m: &mut [u8],
    &Nonce(ref n): &Nonce,
    &PublicKey(ref pk): &PublicKey,
    &SecretKey(ref sk): &SecretKey,
) -> Tag {
    let mut tag = [0; MACBYTES];
    unsafe {
        let _ = ffi::crypto_box_detached(
            m.as_mut_ptr(),
            tag.as_mut_ptr(),
            m.as_ptr(),
            m.len() as u64,
            n.as_ptr(),
            pk.as_ptr(),
            sk.as_ptr(),
        );
    };
    Tag(tag)
}

/// `open()` verifies and decrypts a ciphertext `c` using the receiver's secret key `sk`,
/// the senders public key `pk`, and a nonce `n`. It returns a plaintext `Ok(m)`.
/// If the ciphertext fails verification, `open()` returns `Err(())`.
pub fn open(
    c: &[u8],
    &Nonce(ref n): &Nonce,
    &PublicKey(ref pk): &PublicKey,
    &SecretKey(ref sk): &SecretKey,
) -> Result<Vec<u8>, ()> {
    if c.len() < MACBYTES {
        return Err(());
    }
    let mlen = c.len() - MACBYTES;
    let mut m = Vec::with_capacity(mlen);
    let ret = unsafe {
        m.set_len(mlen);
        ffi::crypto_box_open_easy(
            m.as_mut_ptr(),
            c.as_ptr(),
            c.len() as u64,
            n.as_ptr(),
            pk.as_ptr(),
            sk.as_ptr(),
        )
    };
    if ret == 0 {
        Ok(m)
    } else {
        Err(())
    }
}

/// `open_detached()` verifies and decrypts a ciphertext `c` using the receiver's secret key `sk`,
/// the senders public key `pk`, and a nonce `n`. `c` is decrypted in place, so if this function is
/// successful it will contain the plaintext. If the ciphertext fails verification,
/// `open_detached()` returns `Err(())`, and the ciphertext is not modified.
pub fn open_detached(
    c: &mut [u8],
    mac: &Tag,
    &Nonce(ref n): &Nonce,
    &PublicKey(ref pk): &PublicKey,
    &SecretKey(ref sk): &SecretKey,
) -> Result<(), ()> {
    let ret = unsafe {
        ffi::crypto_box_open_detached(
            c.as_mut_ptr(),
            c.as_ptr(),
            mac.0.as_ptr(),
            c.len() as u64,
            n.as_ptr(),
            pk.as_ptr(),
            sk.as_ptr(),
        )
    };
    if ret == 0 {
        Ok(())
    } else {
        Err(())
    }
}

new_type! {
    /// Applications that send several messages to the same receiver can gain speed by
    /// splitting `seal()` into two steps, `precompute()` and `seal_precomputed()`.
    /// Similarly, applications that receive several messages from the same sender can gain
    /// speed by splitting `open()` into two steps, `precompute()` and `open_precomputed()`.
    ///
    /// When a `PrecomputedKey` goes out of scope its contents will be zeroed out
    secret PrecomputedKey(PRECOMPUTEDKEYBYTES);
}

/// `precompute()` computes an intermediate key that can be used by `seal_precomputed()`
/// and `open_precomputed()`
pub fn precompute(
    &PublicKey(ref pk): &PublicKey,
    &SecretKey(ref sk): &SecretKey,
) -> PrecomputedKey {
    let mut k = [0u8; PRECOMPUTEDKEYBYTES];
    unsafe {
        let _todo_use_result = ffi::crypto_box_curve25519xsalsa20poly1305_beforenm(
            k.as_mut_ptr(),
            pk.as_ptr(),
            sk.as_ptr(),
        );
    }
    PrecomputedKey(k)
}

/// `seal_precomputed()` encrypts and authenticates a message `m` using a precomputed key `k`,
/// and a nonce `n`. It returns a ciphertext `c`.
pub fn seal_precomputed(
    m: &[u8],
    &Nonce(ref n): &Nonce,
    &PrecomputedKey(ref k): &PrecomputedKey,
) -> Vec<u8> {
    let clen = m.len() + MACBYTES;
    let mut c = Vec::with_capacity(clen);
    unsafe {
        c.set_len(clen);
        let _ = ffi::crypto_box_easy_afternm(
            c.as_mut_ptr(),
            m.as_ptr(),
            m.len() as u64,
            n.as_ptr(),
            k.as_ptr(),
        );
    }
    c
}

/// `seal_detached_precomputed()` encrypts and authenticates a message `m` using a precomputed key
/// `k` and a nonce `n`. `m` is encrypted in place, so after this function returns it will contain
/// the ciphertext. The detached authentication tag is returned by value.
pub fn seal_detached_precomputed(
    m: &mut [u8],
    &Nonce(ref n): &Nonce,
    &PrecomputedKey(ref k): &PrecomputedKey,
) -> Tag {
    let mut tag = [0; MACBYTES];
    unsafe {
        let _ = ffi::crypto_box_detached_afternm(
            m.as_mut_ptr(),
            tag.as_mut_ptr(),
            m.as_ptr(),
            m.len() as u64,
            n.as_ptr(),
            k.as_ptr(),
        );
    };
    Tag(tag)
}

/// `open_precomputed()` verifies and decrypts a ciphertext `c` using a precomputed
/// key `k` and a nonce `n`. It returns a plaintext `Ok(m)`.
/// If the ciphertext fails verification, `open_precomputed()` returns `Err(())`.
pub fn open_precomputed(
    c: &[u8],
    &Nonce(ref n): &Nonce,
    &PrecomputedKey(ref k): &PrecomputedKey,
) -> Result<Vec<u8>, ()> {
    if c.len() < MACBYTES {
        return Err(());
    }
    let mlen = c.len() - MACBYTES;
    let mut m = Vec::with_capacity(mlen);
    let ret = unsafe {
        m.set_len(mlen);
        ffi::crypto_box_open_easy_afternm(
            m.as_mut_ptr(),
            c.as_ptr(),
            c.len() as u64,
            n.as_ptr(),
            k.as_ptr(),
        )
    };
    if ret == 0 {
        Ok(m)
    } else {
        Err(())
    }
}

/// `open_detached_precomputed()` verifies and decrypts a ciphertext `c` using a precomputed key
/// `k` and a nonce `n`. `c` is decrypted in place, so if this function is successful it will
/// contain the plaintext. If the ciphertext fails verification, `open_detached()` returns
/// `Err(())`, and the ciphertext is not modified.
pub fn open_detached_precomputed(
    c: &mut [u8],
    mac: &Tag,
    &Nonce(ref n): &Nonce,
    &PrecomputedKey(ref k): &PrecomputedKey,
) -> Result<(), ()> {
    let ret = unsafe {
        ffi::crypto_box_open_detached_afternm(
            c.as_mut_ptr(),
            c.as_ptr(),
            mac.0.as_ptr(),
            c.len() as u64,
            n.as_ptr(),
            k.as_ptr(),
        )
    };
    if ret == 0 {
        Ok(())
    } else {
        Err(())
    }
}

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

    #[test]
    fn test_seal_open() {
        use randombytes::randombytes;
        unwrap!(::init());
        for i in 0..256usize {
            let (pk1, sk1) = gen_keypair();
            let (pk2, sk2) = gen_keypair();
            let m = randombytes(i);
            let n = gen_nonce();
            let c = seal(&m, &n, &pk1, &sk2);
            let opened = open(&c, &n, &pk2, &sk1);
            assert!(Ok(m) == opened);
        }
    }

    #[test]
    fn test_seal_open_precomputed() {
        use randombytes::randombytes;
        unwrap!(::init());
        for i in 0..256usize {
            let (pk1, sk1) = gen_keypair();
            let (pk2, sk2) = gen_keypair();
            let k1 = precompute(&pk1, &sk2);
            let PrecomputedKey(k1buf) = k1;
            let k2 = precompute(&pk2, &sk1);
            let PrecomputedKey(k2buf) = k2;
            assert!(k1buf == k2buf);
            let m = randombytes(i);
            let n = gen_nonce();
            let c = seal_precomputed(&m, &n, &k1);
            let opened = open_precomputed(&c, &n, &k2);
            assert!(Ok(m) == opened);
        }
    }

    #[test]
    fn test_seal_open_tamper() {
        use randombytes::randombytes;
        unwrap!(::init());
        for i in 0..32usize {
            let (pk1, sk1) = gen_keypair();
            let (pk2, sk2) = gen_keypair();
            let m = randombytes(i);
            let n = gen_nonce();
            let mut c = seal(&m, &n, &pk1, &sk2);
            for j in 0..c.len() {
                c[j] ^= 0x20;
                assert!(Err(()) == open(&c, &n, &pk2, &sk1));
                c[j] ^= 0x20;
            }
        }
    }

    #[test]
    fn test_seal_open_precomputed_tamper() {
        use randombytes::randombytes;
        unwrap!(::init());
        for i in 0..32usize {
            let (pk1, sk1) = gen_keypair();
            let (pk2, sk2) = gen_keypair();
            let k1 = precompute(&pk1, &sk2);
            let k2 = precompute(&pk2, &sk1);
            let m = randombytes(i);
            let n = gen_nonce();
            let mut c = seal_precomputed(&m, &n, &k1);
            for j in 0..c.len() {
                c[j] ^= 0x20;
                assert!(Err(()) == open_precomputed(&c, &n, &k2));
                c[j] ^= 0x20;
            }
        }
    }

    #[test]
    fn test_seal_open_detached() {
        use randombytes::randombytes;
        unwrap!(::init());
        for i in 0..256usize {
            let (pk1, sk1) = gen_keypair();
            let (pk2, sk2) = gen_keypair();
            let m = randombytes(i);
            let n = gen_nonce();
            let mut buf = m.clone();
            let tag = seal_detached(&mut buf, &n, &pk1, &sk2);
            unwrap!(open_detached(&mut buf, &tag, &n, &pk2, &sk1));
            assert_eq!(m, buf);
        }
    }

    #[test]
    fn test_seal_combined_then_open_detached() {
        use randombytes::randombytes;
        unwrap!(::init());
        for i in 0..256usize {
            let (pk1, sk1) = gen_keypair();
            let (pk2, sk2) = gen_keypair();
            let m = randombytes(i);
            let n = gen_nonce();
            let mut c = seal(&m, &n, &pk1, &sk2);
            let tag = unwrap!(Tag::from_slice(&c[..MACBYTES]));
            let buf = &mut c[MACBYTES..];
            unwrap!(open_detached(buf, &tag, &n, &pk2, &sk1));
            assert_eq!(buf, &*m);
        }
    }

    #[test]
    fn test_seal_detached_then_open_combined() {
        use randombytes::randombytes;
        unwrap!(::init());
        for i in 0..256usize {
            let (pk1, sk1) = gen_keypair();
            let (pk2, sk2) = gen_keypair();
            let m = randombytes(i);
            let n = gen_nonce();
            let mut buf = vec![0; MACBYTES];
            buf.extend_from_slice(&m);
            let tag = seal_detached(&mut buf[MACBYTES..], &n, &pk1, &sk2);
            buf[..MACBYTES].copy_from_slice(&tag.0[..]);
            let opened = open(&buf, &n, &pk2, &sk1);
            assert_eq!(Ok(m), opened);
        }
    }

    #[test]
    fn test_seal_open_detached_tamper() {
        use randombytes::randombytes;
        unwrap!(::init());
        for i in 0..32usize {
            let (pk1, sk1) = gen_keypair();
            let (pk2, sk2) = gen_keypair();
            let mut m = randombytes(i);
            let n = gen_nonce();
            let mut tag = seal_detached(&mut m, &n, &pk1, &sk2);
            for j in 0..m.len() {
                m[j] ^= 0x20;
                assert_eq!(Err(()), open_detached(&mut m, &tag, &n, &pk2, &sk1));
                m[j] ^= 0x20;
            }
            for j in 0..tag.0.len() {
                tag.0[j] ^= 0x20;
                assert_eq!(Err(()), open_detached(&mut m, &tag, &n, &pk2, &sk1));
                tag.0[j] ^= 0x20;
            }
        }
    }

    #[test]
    fn test_open_detached_failure_does_not_modify() {
        unwrap!(::init());
        let mut buf = b"hello world".to_vec();
        let (pk1, sk1) = gen_keypair();
        let (pk2, sk2) = gen_keypair();
        let n = gen_nonce();
        let tag = seal_detached(&mut buf, &n, &pk1, &sk2);
        // Flip the last bit in the ciphertext, to break authentication.
        *unwrap!(buf.last_mut()) ^= 1;
        // Make a copy that we can compare against after the failure below.
        let copy = buf.clone();
        // Now try to open the message. This will fail.
        let failure = open_detached(&mut buf, &tag, &n, &pk2, &sk1);
        assert!(failure.is_err());
        // Make sure the input hasn't been touched.
        assert_eq!(
            buf, copy,
            "input should not be modified if authentication fails"
        );
    }

    #[test]
    fn test_seal_open_detached_precomputed() {
        use randombytes::randombytes;
        unwrap!(::init());
        for i in 0..256usize {
            let (pk1, sk1) = gen_keypair();
            let (pk2, sk2) = gen_keypair();
            let k1 = precompute(&pk1, &sk2);
            let k2 = precompute(&pk2, &sk1);
            let m = randombytes(i);
            let n = gen_nonce();
            let mut buf = m.clone();
            let tag = seal_detached_precomputed(&mut buf, &n, &k1);
            unwrap!(open_detached_precomputed(&mut buf, &tag, &n, &k2));
            assert_eq!(m, buf);
        }
    }

    #[test]
    fn test_seal_combined_then_open_detached_precomputed() {
        use randombytes::randombytes;
        unwrap!(::init());
        for i in 0..256usize {
            let (pk1, sk1) = gen_keypair();
            let (pk2, sk2) = gen_keypair();
            let k1 = precompute(&pk1, &sk2);
            let k2 = precompute(&pk2, &sk1);
            let m = randombytes(i);
            let n = gen_nonce();
            let mut c = seal_precomputed(&m, &n, &k1);
            let tag = unwrap!(Tag::from_slice(&c[..MACBYTES]));
            let buf = &mut c[MACBYTES..];
            unwrap!(open_detached_precomputed(buf, &tag, &n, &k2));
            assert_eq!(buf, &*m);
        }
    }

    #[test]
    fn test_seal_detached_precomputed_then_open_combined() {
        use randombytes::randombytes;
        unwrap!(::init());
        for i in 0..256usize {
            let (pk1, sk1) = gen_keypair();
            let (pk2, sk2) = gen_keypair();
            let k1 = precompute(&pk1, &sk2);
            let k2 = precompute(&pk2, &sk1);
            let m = randombytes(i);
            let n = gen_nonce();
            let mut buf = vec![0; MACBYTES];
            buf.extend_from_slice(&m);
            let tag = seal_detached_precomputed(&mut buf[MACBYTES..], &n, &k1);
            buf[..MACBYTES].copy_from_slice(&tag.0[..]);
            let opened = open_precomputed(&buf, &n, &k2);
            assert_eq!(Ok(m), opened);
        }
    }

    #[test]
    fn test_seal_open_detached_precomputed_tamper() {
        use randombytes::randombytes;
        unwrap!(::init());
        for i in 0..32usize {
            let (pk1, sk1) = gen_keypair();
            let (pk2, sk2) = gen_keypair();
            let k1 = precompute(&pk1, &sk2);
            let k2 = precompute(&pk2, &sk1);
            let mut m = randombytes(i);
            let n = gen_nonce();
            let mut tag = seal_detached_precomputed(&mut m, &n, &k1);
            for j in 0..m.len() {
                m[j] ^= 0x20;
                assert_eq!(Err(()), open_detached_precomputed(&mut m, &tag, &n, &k2));
                m[j] ^= 0x20;
            }
            for j in 0..tag.0.len() {
                tag.0[j] ^= 0x20;
                assert_eq!(Err(()), open_detached_precomputed(&mut m, &tag, &n, &k2));
                tag.0[j] ^= 0x20;
            }
        }
    }

    #[test]
    fn test_open_detached_precomputed_failure_does_not_modify() {
        unwrap!(::init());
        let mut buf = b"hello world".to_vec();
        let (pk1, sk1) = gen_keypair();
        let (pk2, sk2) = gen_keypair();
        let k1 = precompute(&pk1, &sk2);
        let k2 = precompute(&pk2, &sk1);
        let n = gen_nonce();
        let tag = seal_detached_precomputed(&mut buf, &n, &k1);
        // Flip the last bit in the ciphertext, to break authentication.
        *unwrap!(buf.last_mut()) ^= 1;
        // Make a copy that we can compare against after the failure below.
        let copy = buf.clone();
        // Now try to open the message. This will fail.
        let failure = open_detached_precomputed(&mut buf, &tag, &n, &k2);
        assert!(failure.is_err());
        // Make sure the input hasn't been touched.
        assert_eq!(
            buf, copy,
            "input should not be modified if authentication fails"
        );
    }

    #[test]
    #[cfg_attr(rustfmt, rustfmt_skip)]
    fn test_vector_1() {
        // corresponding to tests/box.c and tests/box3.cpp from NaCl
        unwrap!(::init());
        let alicesk = SecretKey([0x77, 0x07, 0x6d, 0x0a, 0x73, 0x18, 0xa5, 0x7d, 0x3c, 0x16,
                                 0xc1, 0x72, 0x51, 0xb2, 0x66, 0x45, 0xdf, 0x4c, 0x2f, 0x87,
                                 0xeb, 0xc0, 0x99, 0x2a, 0xb1, 0x77, 0xfb, 0xa5, 0x1d, 0xb9,
                                 0x2c, 0x2a]);
        let bobpk = PublicKey([0xde, 0x9e, 0xdb, 0x7d, 0x7b, 0x7d, 0xc1, 0xb4, 0xd3, 0x5b, 0x61,
                               0xc2, 0xec, 0xe4, 0x35, 0x37, 0x3f, 0x83, 0x43, 0xc8, 0x5b, 0x78,
                               0x67, 0x4d, 0xad, 0xfc, 0x7e, 0x14, 0x6f, 0x88, 0x2b, 0x4f]);
        let nonce = Nonce([0x69, 0x69, 0x6e, 0xe9, 0x55, 0xb6, 0x2b, 0x73, 0xcd, 0x62, 0xbd,
                           0xa8, 0x75, 0xfc, 0x73, 0xd6, 0x82, 0x19, 0xe0, 0x03, 0x6b, 0x7a,
                           0x0b, 0x37]);
        let m = [0xbe, 0x07, 0x5f, 0xc5, 0x3c, 0x81, 0xf2, 0xd5, 0xcf, 0x14, 0x13, 0x16, 0xeb,
                 0xeb, 0x0c, 0x7b, 0x52, 0x28, 0xc5, 0x2a, 0x4c, 0x62, 0xcb, 0xd4, 0x4b, 0x66,
                 0x84, 0x9b, 0x64, 0x24, 0x4f, 0xfc, 0xe5, 0xec, 0xba, 0xaf, 0x33, 0xbd, 0x75,
                 0x1a, 0x1a, 0xc7, 0x28, 0xd4, 0x5e, 0x6c, 0x61, 0x29, 0x6c, 0xdc, 0x3c, 0x01,
                 0x23, 0x35, 0x61, 0xf4, 0x1d, 0xb6, 0x6c, 0xce, 0x31, 0x4a, 0xdb, 0x31, 0x0e,
                 0x3b, 0xe8, 0x25, 0x0c, 0x46, 0xf0, 0x6d, 0xce, 0xea, 0x3a, 0x7f, 0xa1, 0x34,
                 0x80, 0x57, 0xe2, 0xf6, 0x55, 0x6a, 0xd6, 0xb1, 0x31, 0x8a, 0x02, 0x4a, 0x83,
                 0x8f, 0x21, 0xaf, 0x1f, 0xde, 0x04, 0x89, 0x77, 0xeb, 0x48, 0xf5, 0x9f, 0xfd,
                 0x49, 0x24, 0xca, 0x1c, 0x60, 0x90, 0x2e, 0x52, 0xf0, 0xa0, 0x89, 0xbc, 0x76,
                 0x89, 0x70, 0x40, 0xe0, 0x82, 0xf9, 0x37, 0x76, 0x38, 0x48, 0x64, 0x5e, 0x07,
                 0x05];
        let c = seal(&m, &nonce, &bobpk, &alicesk);
        let pk = precompute(&bobpk, &alicesk);
        let cpre = seal_precomputed(&m, &nonce, &pk);
        let cexp = vec![0xf3, 0xff, 0xc7, 0x70, 0x3f, 0x94, 0x00, 0xe5, 0x2a, 0x7d, 0xfb, 0x4b,
                        0x3d, 0x33, 0x05, 0xd9, 0x8e, 0x99, 0x3b, 0x9f, 0x48, 0x68, 0x12, 0x73,
                        0xc2, 0x96, 0x50, 0xba, 0x32, 0xfc, 0x76, 0xce, 0x48, 0x33, 0x2e, 0xa7,
                        0x16, 0x4d, 0x96, 0xa4, 0x47, 0x6f, 0xb8, 0xc5, 0x31, 0xa1, 0x18, 0x6a,
                        0xc0, 0xdf, 0xc1, 0x7c, 0x98, 0xdc, 0xe8, 0x7b, 0x4d, 0xa7, 0xf0, 0x11,
                        0xec, 0x48, 0xc9, 0x72, 0x71, 0xd2, 0xc2, 0x0f, 0x9b, 0x92, 0x8f, 0xe2,
                        0x27, 0x0d, 0x6f, 0xb8, 0x63, 0xd5, 0x17, 0x38, 0xb4, 0x8e, 0xee, 0xe3,
                        0x14, 0xa7, 0xcc, 0x8a, 0xb9, 0x32, 0x16, 0x45, 0x48, 0xe5, 0x26, 0xae,
                        0x90, 0x22, 0x43, 0x68, 0x51, 0x7a, 0xcf, 0xea, 0xbd, 0x6b, 0xb3, 0x73,
                        0x2b, 0xc0, 0xe9, 0xda, 0x99, 0x83, 0x2b, 0x61, 0xca, 0x01, 0xb6, 0xde,
                        0x56, 0x24, 0x4a, 0x9e, 0x88, 0xd5, 0xf9, 0xb3, 0x79, 0x73, 0xf6, 0x22,
                        0xa4, 0x3d, 0x14, 0xa6, 0x59, 0x9b, 0x1f, 0x65, 0x4c, 0xb4, 0x5a, 0x74,
                        0xe3, 0x55, 0xa5];
        assert!(c == cexp);
        assert!(cpre == cexp);
    }

    #[test]
    #[cfg_attr(rustfmt, rustfmt_skip)]
    fn test_vector_2() {
        // corresponding to tests/box2.c and tests/box4.cpp from NaCl
        unwrap!(::init());
        let bobsk = SecretKey([0x5d, 0xab, 0x08, 0x7e, 0x62, 0x4a, 0x8a, 0x4b, 0x79, 0xe1, 0x7f,
                               0x8b, 0x83, 0x80, 0x0e, 0xe6, 0x6f, 0x3b, 0xb1, 0x29, 0x26, 0x18,
                               0xb6, 0xfd, 0x1c, 0x2f, 0x8b, 0x27, 0xff, 0x88, 0xe0, 0xeb]);
        let alicepk = PublicKey([0x85, 0x20, 0xf0, 0x09, 0x89, 0x30, 0xa7, 0x54, 0x74, 0x8b,
                                 0x7d, 0xdc, 0xb4, 0x3e, 0xf7, 0x5a, 0x0d, 0xbf, 0x3a, 0x0d,
                                 0x26, 0x38, 0x1a, 0xf4, 0xeb, 0xa4, 0xa9, 0x8e, 0xaa, 0x9b,
                                 0x4e, 0x6a]);
        let nonce = Nonce([0x69, 0x69, 0x6e, 0xe9, 0x55, 0xb6, 0x2b, 0x73, 0xcd, 0x62, 0xbd,
                           0xa8, 0x75, 0xfc, 0x73, 0xd6, 0x82, 0x19, 0xe0, 0x03, 0x6b, 0x7a,
                           0x0b, 0x37]);
        let c = [0xf3, 0xff, 0xc7, 0x70, 0x3f, 0x94, 0x00, 0xe5, 0x2a, 0x7d, 0xfb, 0x4b, 0x3d,
                 0x33, 0x05, 0xd9, 0x8e, 0x99, 0x3b, 0x9f, 0x48, 0x68, 0x12, 0x73, 0xc2, 0x96,
                 0x50, 0xba, 0x32, 0xfc, 0x76, 0xce, 0x48, 0x33, 0x2e, 0xa7, 0x16, 0x4d, 0x96,
                 0xa4, 0x47, 0x6f, 0xb8, 0xc5, 0x31, 0xa1, 0x18, 0x6a, 0xc0, 0xdf, 0xc1, 0x7c,
                 0x98, 0xdc, 0xe8, 0x7b, 0x4d, 0xa7, 0xf0, 0x11, 0xec, 0x48, 0xc9, 0x72, 0x71,
                 0xd2, 0xc2, 0x0f, 0x9b, 0x92, 0x8f, 0xe2, 0x27, 0x0d, 0x6f, 0xb8, 0x63, 0xd5,
                 0x17, 0x38, 0xb4, 0x8e, 0xee, 0xe3, 0x14, 0xa7, 0xcc, 0x8a, 0xb9, 0x32, 0x16,
                 0x45, 0x48, 0xe5, 0x26, 0xae, 0x90, 0x22, 0x43, 0x68, 0x51, 0x7a, 0xcf, 0xea,
                 0xbd, 0x6b, 0xb3, 0x73, 0x2b, 0xc0, 0xe9, 0xda, 0x99, 0x83, 0x2b, 0x61, 0xca,
                 0x01, 0xb6, 0xde, 0x56, 0x24, 0x4a, 0x9e, 0x88, 0xd5, 0xf9, 0xb3, 0x79, 0x73,
                 0xf6, 0x22, 0xa4, 0x3d, 0x14, 0xa6, 0x59, 0x9b, 0x1f, 0x65, 0x4c, 0xb4, 0x5a,
                 0x74, 0xe3, 0x55, 0xa5];
        let mexp = Ok(vec![0xbe, 0x07, 0x5f, 0xc5, 0x3c, 0x81, 0xf2, 0xd5, 0xcf, 0x14, 0x13,
                           0x16, 0xeb, 0xeb, 0x0c, 0x7b, 0x52, 0x28, 0xc5, 0x2a, 0x4c, 0x62,
                           0xcb, 0xd4, 0x4b, 0x66, 0x84, 0x9b, 0x64, 0x24, 0x4f, 0xfc, 0xe5,
                           0xec, 0xba, 0xaf, 0x33, 0xbd, 0x75, 0x1a, 0x1a, 0xc7, 0x28, 0xd4,
                           0x5e, 0x6c, 0x61, 0x29, 0x6c, 0xdc, 0x3c, 0x01, 0x23, 0x35, 0x61,
                           0xf4, 0x1d, 0xb6, 0x6c, 0xce, 0x31, 0x4a, 0xdb, 0x31, 0x0e, 0x3b,
                           0xe8, 0x25, 0x0c, 0x46, 0xf0, 0x6d, 0xce, 0xea, 0x3a, 0x7f, 0xa1,
                           0x34, 0x80, 0x57, 0xe2, 0xf6, 0x55, 0x6a, 0xd6, 0xb1, 0x31, 0x8a,
                           0x02, 0x4a, 0x83, 0x8f, 0x21, 0xaf, 0x1f, 0xde, 0x04, 0x89, 0x77,
                           0xeb, 0x48, 0xf5, 0x9f, 0xfd, 0x49, 0x24, 0xca, 0x1c, 0x60, 0x90,
                           0x2e, 0x52, 0xf0, 0xa0, 0x89, 0xbc, 0x76, 0x89, 0x70, 0x40, 0xe0,
                           0x82, 0xf9, 0x37, 0x76, 0x38, 0x48, 0x64, 0x5e, 0x07, 0x05]);
        let m = open(&c, &nonce, &alicepk, &bobsk);
        let pk = precompute(&alicepk, &bobsk);
        let m_pre = open_precomputed(&c, &nonce, &pk);
        assert!(m == mexp);
        assert!(m_pre == mexp);
    }

    #[test]
    fn test_public_key() {
        unwrap!(::init());
        for _ in 0..256usize {
            let (pk1, sk) = gen_keypair();
            let pk2 = sk.public_key();
            assert_eq!(pk1, pk2);
        }
    }

    #[test]
    fn test_serialisation() {
        use test_utils::round_trip;
        unwrap!(::init());
        for _ in 0..256usize {
            let (pk, sk) = gen_keypair();
            let n = gen_nonce();
            round_trip(&pk);
            round_trip(&sk);
            round_trip(&n);
        }
    }
}

#[cfg(feature = "benchmarks")]
#[cfg(test)]
mod bench {
    extern crate test;
    use super::*;
    use randombytes::randombytes;

    const BENCH_SIZES: [usize; 14] = [0, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096];

    #[bench]
    fn bench_seal_open(b: &mut test::Bencher) {
        unwrap!(::init());
        let (pk, sk) = gen_keypair();
        let n = gen_nonce();
        let ms: Vec<Vec<u8>> = BENCH_SIZES.iter().map(|s| randombytes(*s)).collect();
        b.iter(|| {
            for m in ms.iter() {
                unwrap!(open(&seal(m, &n, &pk, &sk), &n, &pk, &sk));
            }
        });
    }

    #[bench]
    fn bench_precompute(b: &mut test::Bencher) {
        unwrap!(::init());
        let (pk, sk) = gen_keypair();
        b.iter(|| {
            // we do this benchmark as many times as the other benchmarks so
            // that we can compare the times
            for _ in BENCH_SIZES.iter() {
                precompute(&pk, &sk);
                precompute(&pk, &sk);
            }
        });
    }
}