pqcrypto-sphincsplus 0.3.2

//! sphincs-shake256-128f-simple
//!
//! These bindings use the clean version from [PQClean][pqc]
//!
//! # Example
//! ```
//! use pqcrypto_sphincsplus::sphincsshake256128fsimple::*;
//! let message = vec![0, 1, 2, 3, 4, 5];
//! let (pk, sk) = keypair();
//! let sm = sign(&message, &sk);
//! let verifiedmsg = open(&sm, &pk).unwrap();
//! assert!(verifiedmsg == message);
//! ```
//!
//! [pqc]: https://github.com/pqclean/pqclean/

// This file is generated.

use std::mem;

use crate::ffi;
use pqcrypto_traits::sign as primitive;

macro_rules! simple_struct {
    ($type: ident, $size: expr) => {
        #[derive(Clone)]
        pub struct $type([u8; $size]);

        impl $type {
            /// Generates an uninitialized object
            ///
            /// Used to pass to ``ffi`` interfaces.
            ///
            /// Internal use only!
            fn new() -> Self {
                $type(unsafe { mem::uninitialized() })
            }
        }

        impl primitive::$type for $type {
            /// Get this object as a byte slice
            #[inline]
            fn as_bytes(&self) -> &[u8] {
                &self.0
            }

            /// Construct this object from a byte slice
            fn from_bytes(bytes: &[u8]) -> Self {
                let mut array: [u8; $size] = unsafe { mem::uninitialized() };
                array.copy_from_slice(bytes);
                $type(array)
            }
        }

        impl PartialEq for $type {
            /// By no means constant time comparison
            fn eq(&self, other: &Self) -> bool {
                self.0
                    .iter()
                    .zip(other.0.iter())
                    .try_for_each(|(a, b)| if a == b { Ok(()) } else { Err(()) })
                    .is_ok()
            }
        }
    };
}

simple_struct!(
    PublicKey,
    ffi::PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_PUBLICKEYBYTES
);
simple_struct!(
    SecretKey,
    ffi::PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_SECRETKEYBYTES
);
#[derive(Clone)]
pub struct DetachedSignature(
    [u8; ffi::PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_BYTES],
    usize,
);

impl DetachedSignature {
    fn new() -> Self {
        DetachedSignature(unsafe { mem::uninitialized() }, 0)
    }
}

impl primitive::DetachedSignature for DetachedSignature {
    /// Get this object as a byte slice
    #[inline]
    fn as_bytes(&self) -> &[u8] {
        &self.0[..self.1]
    }

    #[inline]
    fn from_bytes(bytes: &[u8]) -> Self {
        debug_assert!(bytes.len() <= ffi::PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_BYTES);
        let mut array: [u8; ffi::PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_BYTES] =
            unsafe { mem::uninitialized() };
        array.copy_from_slice(bytes);
        DetachedSignature(array, bytes.len())
    }
}

#[derive(Clone)]
pub struct SignedMessage(Vec<u8>);
impl primitive::SignedMessage for SignedMessage {
    /// Get this object as a byte slice
    #[inline]
    fn as_bytes(&self) -> &[u8] {
        &self.0.as_slice()
    }

    /// Construct this object from a byte slice
    #[inline]
    fn from_bytes(bytes: &[u8]) -> Self {
        SignedMessage(bytes.to_vec())
    }
}

impl SignedMessage {
    pub fn len(&self) -> usize {
        let len = self.0.len();
        debug_assert!(len > signature_bytes());
        len
    }
}

/// Get the number of bytes for a public key
pub const fn public_key_bytes() -> usize {
    ffi::PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_PUBLICKEYBYTES
}

/// Get the number of bytes for a secret key
pub const fn secret_key_bytes() -> usize {
    ffi::PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_SECRETKEYBYTES
}

/// Get the number of bytes that a signature occupies
pub const fn signature_bytes() -> usize {
    ffi::PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_BYTES
}

/// Generate a sphincs-shake256-128f-simple keypair
pub fn keypair() -> (PublicKey, SecretKey) {
    let mut pk = PublicKey::new();
    let mut sk = SecretKey::new();
    assert_eq!(
        unsafe {
            ffi::PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_keypair(
                pk.0.as_mut_ptr(),
                sk.0.as_mut_ptr(),
            )
        },
        0
    );
    (pk, sk)
}

pub fn sign(msg: &[u8], sk: &SecretKey) -> SignedMessage {
    let max_len = msg.len() + signature_bytes();
    let mut signed_msg = Vec::with_capacity(max_len);
    let mut smlen: usize = 0;
    unsafe {
        ffi::PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign(
            signed_msg.as_mut_ptr(),
            &mut smlen as *mut usize,
            msg.as_ptr(),
            msg.len(),
            sk.0.as_ptr(),
        );
        debug_assert!(smlen <= max_len, "exceeded Vec capacity");
        signed_msg.set_len(smlen);
    }
    SignedMessage(signed_msg)
}

#[must_use]
pub fn open(sm: &SignedMessage, pk: &PublicKey) -> Result<Vec<u8>, primitive::VerificationError> {
    let mut m: Vec<u8> = Vec::with_capacity(sm.len());
    let mut mlen: usize = 0;
    match unsafe {
        ffi::PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_open(
            m.as_mut_ptr(),
            &mut mlen as *mut usize,
            sm.0.as_ptr(),
            sm.len(),
            pk.0.as_ptr(),
        )
    } {
        0 => {
            unsafe { m.set_len(mlen) };
            Ok(m)
        }
        -1 => Err(primitive::VerificationError::InvalidSignature),
        _ => Err(primitive::VerificationError::UnknownVerificationError),
    }
}

pub fn detached_sign(msg: &[u8], sk: &SecretKey) -> DetachedSignature {
    let mut sig = DetachedSignature::new();
    unsafe {
        ffi::PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_signature(
            sig.0.as_mut_ptr(),
            &mut sig.1 as *mut usize,
            msg.as_ptr(),
            msg.len(),
            sk.0.as_ptr(),
        );
    }
    sig
}

#[must_use]
pub fn verify_detached_signature(
    sig: &DetachedSignature,
    msg: &[u8],
    pk: &PublicKey,
) -> Result<(), primitive::VerificationError> {
    let res = unsafe {
        ffi::PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_verify(
            sig.0.as_ptr(),
            sig.1,
            msg.as_ptr(),
            msg.len(),
            pk.0.as_ptr(),
        )
    };
    match res {
        0 => Ok(()),
        -1 => Err(primitive::VerificationError::InvalidSignature),
        _ => Err(primitive::VerificationError::UnknownVerificationError),
    }
}

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

    #[test]
    pub fn test_sign() {
        let mut rng = rand::thread_rng();
        let len: u16 = rng.gen();

        let message = (0..len).map(|_| rng.gen::<u8>()).collect::<Vec<_>>();
        let (pk, sk) = keypair();
        let sm = sign(&message, &sk);
        let verifiedmsg = open(&sm, &pk).unwrap();
        assert!(verifiedmsg == message);
    }

    #[test]
    pub fn test_sign_detached() {
        let mut rng = rand::thread_rng();
        let len: u16 = rng.gen();
        let message = (0..len).map(|_| rng.gen::<u8>()).collect::<Vec<_>>();

        let (pk, sk) = keypair();
        let sig = detached_sign(&message, &sk);
        assert!(verify_detached_signature(&sig, &message, &pk).is_ok());
        assert!(!verify_detached_signature(&sig, &message[..message.len() - 1], &pk).is_ok());
    }
}