oqs/

sig.rs

//! Signature API
//!
//! See [`Sig`] for the main functionality and [`Algorithm`]
//! for the list of supported algorithms.
use alloc::vec::Vec;

use core::ptr::{null, NonNull};
use core::str::FromStr;

#[cfg(not(feature = "std"))]
use cstr_core::CStr;
#[cfg(feature = "std")]
use std::ffi::CStr;

use crate::ffi::sig as ffi;
use crate::newtype_buffer;
use crate::*;
#[cfg(feature = "rustcrypto")]
use ::signature::Signer as RustCryptoSigner;
#[cfg(feature = "rustcrypto")]
use ::signature::Verifier as RustCryptoVerifier;

#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};

newtype_buffer!(PublicKey, PublicKeyRef);
newtype_buffer!(SecretKey, SecretKeyRef);
newtype_buffer!(Signature, SignatureRef);

/// Message type
pub type Message = [u8];
/// Context string type
pub type CtxStr = [u8];

macro_rules! implement_sigs {
    { $($(#[$test_attr:meta])* ($feat: literal) $sig: ident: $oqs_id: ident),* $(,)? } => (
        /// Supported algorithms by liboqs
        ///
        /// They may not all be enabled
        ///
        /// Optional support for `serde` if that feature is enabled.
        #[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
        #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
        #[allow(missing_docs)]
        pub enum Algorithm {
            $(
                $sig,
            )*
        }

        fn algorithm_to_id(algorithm: Algorithm) -> *const libc::c_char {
            let id: &[u8] = match algorithm {
                $(
                    Algorithm::$sig => &ffi::$oqs_id[..],
                )*
            };
            id as *const _ as *const libc::c_char
        }

        impl FromStr for Algorithm {
            type Err = crate::Error;

            fn from_str(s: &str) -> Result<Self> {
                $(
                    if s == Algorithm::$sig.name() {
                        return Ok(Algorithm::$sig);
                    }
                )*
                Err(crate::Error::AlgorithmParsingError)
            }
        }

        $(
            #[cfg(test)]
            #[allow(non_snake_case)]
            mod $sig {
                use super::*;

                #[test]
                #[cfg(feature = $feat)]
                $(#[$test_attr])*
                fn test_signing() -> Result<()> {
                    crate::init();
                    let message = [0u8; 100];
                    let sig = Sig::new(Algorithm::$sig)?;
                    let (pk, sk) = sig.keypair()?;
                    let signature = sig.sign(&message, &sk)?;
                    sig.verify(&message, &signature, &pk)
                }

                #[test]
                #[cfg(feature = $feat)]
                $(#[$test_attr])*
                fn test_signing_with_empty_context_string() -> Result<()> {
                    crate::init();
                    let message = [0u8; 100];
                    let ctx_str: [u8; 0] = [];
                    let sig = Sig::new(Algorithm::$sig)?;
                    let (pk, sk) = sig.keypair()?;
                    let signature = sig.sign_with_ctx_str(&message, &ctx_str, &sk)?;
                    sig.verify_with_ctx_str(&message, &signature, &ctx_str, &pk)
                }

                #[test]
                #[cfg(feature = $feat)]
                $(#[$test_attr])*
                fn test_signing_with_nonempty_context_string() -> Result<()> {
                    crate::init();
                    let message = [0u8; 100];
                    let ctx_str = [0u8; 100];
                    let sig = Sig::new(Algorithm::$sig)?;
                    let (pk, sk) = sig.keypair()?;
                    if sig.has_ctx_str_support() {
                        let signature = sig.sign_with_ctx_str(&message, &ctx_str, &sk)?;
                        sig.verify_with_ctx_str(&message, &signature, &ctx_str, &pk)
                    } else {
                        let sig_result = sig.sign_with_ctx_str(&message, &ctx_str, &sk);
                        // Expect a generic error
                        let sig_result: Result<()> = match sig_result {
                            Err(Error::Error) => Ok(()),
                            Ok(_) => Err(Error::Error),
                            Err(e) => Err(e)
                        };
                        if sig_result.is_ok() {
                            // get a valid signature with which to test verify
                            let signature = sig.sign(&message, &sk)?;
                            // Expect a generic error
                            match sig.verify_with_ctx_str(&message, &signature, &ctx_str, &pk) {
                                Err(Error::Error) => Ok(()),
                                Ok(_) => Err(Error::Error),
                                Err(e) => Err(e)

                            }
                        } else {
                            sig_result
                        }
                    }
                }

                #[test]
                fn test_enabled() {
                    crate::init();
                    if cfg!(feature = $feat) {
                        assert!(Algorithm::$sig.is_enabled());
                    } else {
                        assert!(!Algorithm::$sig.is_enabled())
                    }
                }

                #[test]
                fn test_name() {
                    let algo = Algorithm::$sig;
                    // Just make sure the name impl does not panic or crash.
                    let name = algo.name();

                    #[cfg(feature = "std")]
                    assert_eq!(name, algo.to_string());

                    // ... And actually contains something.
                    assert!(!name.is_empty());
                }

                #[test]
                fn test_get_algorithm_back() {
                    let algorithm = Algorithm::$sig;
                    if algorithm.is_enabled() {
                        let sig = Sig::new(algorithm).unwrap();
                        assert_eq!(algorithm, sig.algorithm());
                    }
                }

                #[test]
                fn test_version() {
                    if let Ok(sig) = Sig::new(Algorithm::$sig) {
                        // Just make sure the version can be called without panic
                        let version = sig.version();
                        // ... And actually contains something.
                        assert!(!version.is_empty());
                    }
                }

                #[test]
                fn test_from_str() {
                    let algorithm = Algorithm::$sig;
                    let name = algorithm.name();
                    let parsed = Algorithm::from_str(name).unwrap();
                    assert_eq!(algorithm, parsed);}
            }
        )*
    )
}

include!("generated_sig_algorithms.rs");

impl Algorithm {
    /// Returns true if this algorithm is enabled in the linked version
    /// of liboqs
    pub fn is_enabled(self) -> bool {
        unsafe { ffi::OQS_SIG_alg_is_enabled(algorithm_to_id(self)) == 1 }
    }

    /// Provides a pointer to the id of the algorithm
    ///
    /// For use with the FFI api methods
    pub fn to_id(self) -> *const libc::c_char {
        algorithm_to_id(self)
    }

    /// Returns the algorithm's name as a static Rust string.
    ///
    /// This is the same as the `to_id`, but as a safe Rust string.
    pub fn name(&self) -> &'static str {
        // SAFETY: The id from ffi must be a proper null terminated C string
        let id = unsafe { CStr::from_ptr(self.to_id()) };
        id.to_str().expect("OQS algorithm names must be UTF-8")
    }
}

/// Signature scheme
///
/// # Example
/// ```rust
/// # if !cfg!(feature = "ml_dsa") { return; }
/// use oqs;
/// oqs::init();
/// let scheme = oqs::sig::Sig::new(oqs::sig::Algorithm::MlDsa44).unwrap();
/// let message = [0u8; 100];
/// let (pk, sk) = scheme.keypair().unwrap();
/// let signature = scheme.sign(&message, &sk).unwrap();
/// assert!(scheme.verify(&message, &signature, &pk).is_ok());
/// ```
pub struct Sig {
    algorithm: Algorithm,
    sig: NonNull<ffi::OQS_SIG>,
}

unsafe impl Sync for Sig {}
unsafe impl Send for Sig {}

impl Drop for Sig {
    fn drop(&mut self) {
        unsafe { ffi::OQS_SIG_free(self.sig.as_ptr()) };
    }
}

#[cfg(feature = "std")]
impl std::fmt::Display for Algorithm {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        self.name().fmt(f)
    }
}

impl core::convert::TryFrom<Algorithm> for Sig {
    type Error = crate::Error;
    fn try_from(alg: Algorithm) -> Result<Sig> {
        Sig::new(alg)
    }
}

impl Sig {
    /// Construct a new algorithm
    ///
    /// May fail if the algorithm is not available
    pub fn new(algorithm: Algorithm) -> Result<Self> {
        let sig = unsafe { ffi::OQS_SIG_new(algorithm_to_id(algorithm)) };
        NonNull::new(sig).map_or_else(
            || Err(Error::AlgorithmDisabled),
            |sig| Ok(Self { algorithm, sig }),
        )
    }

    /// Get the algorithm used by this `Sig`
    pub fn algorithm(&self) -> Algorithm {
        self.algorithm
    }

    /// Get the version of the implementation
    pub fn version(&self) -> &'static str {
        let sig = unsafe { self.sig.as_ref() };
        // SAFETY: The alg_version from ffi must be a proper null terminated C string
        let cstr = unsafe { CStr::from_ptr(sig.alg_version) };
        cstr.to_str()
            .expect("Algorithm version strings must be UTF-8")
    }

    /// Obtain the claimed nist level
    pub fn claimed_nist_level(&self) -> u8 {
        let sig = unsafe { self.sig.as_ref() };
        sig.claimed_nist_level
    }

    /// Is this algorithm EUF-CMA?
    pub fn is_euf_cma(&self) -> bool {
        let sig = unsafe { self.sig.as_ref() };
        sig.euf_cma
    }

    /// Does this algorithm support signing with a context string?
    pub fn has_ctx_str_support(&self) -> bool {
        let sig = unsafe { self.sig.as_ref() };
        sig.sig_with_ctx_support
    }

    /// Length of the public key
    pub fn length_public_key(&self) -> usize {
        let sig = unsafe { self.sig.as_ref() };
        sig.length_public_key
    }

    /// Length of the secret key
    pub fn length_secret_key(&self) -> usize {
        let sig = unsafe { self.sig.as_ref() };
        sig.length_secret_key
    }

    /// Maximum length of a signature
    pub fn length_signature(&self) -> usize {
        let sig = unsafe { self.sig.as_ref() };
        sig.length_signature
    }

    /// Construct a secret key object from bytes
    pub fn secret_key_from_bytes<'a>(&self, buf: &'a [u8]) -> Option<SecretKeyRef<'a>> {
        if buf.len() != self.length_secret_key() {
            None
        } else {
            Some(SecretKeyRef::new(buf))
        }
    }

    /// Construct a public key object from bytes
    pub fn public_key_from_bytes<'a>(&self, buf: &'a [u8]) -> Option<PublicKeyRef<'a>> {
        if buf.len() != self.length_public_key() {
            None
        } else {
            Some(PublicKeyRef::new(buf))
        }
    }

    /// Construct a signature object from bytes
    pub fn signature_from_bytes<'a>(&self, buf: &'a [u8]) -> Option<SignatureRef<'a>> {
        if buf.len() > self.length_signature() {
            None
        } else {
            Some(SignatureRef::new(buf))
        }
    }

    /// Generate a new keypair
    pub fn keypair(&self) -> Result<(PublicKey, SecretKey)> {
        let sig = unsafe { self.sig.as_ref() };
        let func = sig.keypair.unwrap();
        let mut pk = PublicKey {
            bytes: Vec::with_capacity(sig.length_public_key),
        };
        let mut sk = SecretKey {
            bytes: Vec::with_capacity(sig.length_secret_key),
        };
        let status = unsafe { func(pk.bytes.as_mut_ptr(), sk.bytes.as_mut_ptr()) };
        // update the lengths of the vecs
        unsafe {
            pk.bytes.set_len(sig.length_public_key);
            sk.bytes.set_len(sig.length_secret_key);
        }
        status_to_result(status)?;
        Ok((pk, sk))
    }

    /// Sign a message
    pub fn sign<'a, S: Into<SecretKeyRef<'a>>>(
        &self,
        message: &Message,
        sk: S,
    ) -> Result<Signature> {
        let sk = sk.into();
        let sig = unsafe { self.sig.as_ref() };
        let func = sig.sign.unwrap();
        let mut sig = Signature {
            bytes: Vec::with_capacity(sig.length_signature),
        };
        let mut sig_len = 0;
        let status = unsafe {
            func(
                sig.bytes.as_mut_ptr(),
                &mut sig_len,
                message.as_ptr(),
                message.len(),
                sk.bytes.as_ptr(),
            )
        };
        status_to_result(status)?;
        // This is safe to do as it's initialised now.
        unsafe {
            sig.bytes.set_len(sig_len);
        }
        Ok(sig)
    }

    /// Sign a message with a context string
    pub fn sign_with_ctx_str<'a, S: Into<SecretKeyRef<'a>>>(
        &self,
        message: &Message,
        ctx_str: &CtxStr,
        sk: S,
    ) -> Result<Signature> {
        let sk = sk.into();
        let sig = unsafe { self.sig.as_ref() };
        let func = sig.sign_with_ctx_str.unwrap();
        let mut sig = Signature {
            bytes: Vec::with_capacity(sig.length_signature),
        };
        let mut sig_len = 0;
        // For algorithms without context string support, liboqs
        // expects the context to be NULL. Converting an empty
        // slice to a pointer doesn't actually do this.
        let ctx_str_ptr = if !ctx_str.is_empty() {
            ctx_str.as_ptr()
        } else {
            null()
        };
        let status = unsafe {
            func(
                sig.bytes.as_mut_ptr(),
                &mut sig_len,
                message.as_ptr(),
                message.len(),
                ctx_str_ptr,
                ctx_str.len(),
                sk.bytes.as_ptr(),
            )
        };
        status_to_result(status)?;
        // This is safe to do as it's initialised now.
        unsafe {
            sig.bytes.set_len(sig_len);
        }
        Ok(sig)
    }

    /// Verify a message
    pub fn verify<'a, 'b>(
        &self,
        message: &Message,
        signature: impl Into<SignatureRef<'a>>,
        pk: impl Into<PublicKeyRef<'b>>,
    ) -> Result<()> {
        let signature = signature.into();
        let pk = pk.into();
        if signature.bytes.len() > self.length_signature()
            || pk.bytes.len() != self.length_public_key()
        {
            return Err(Error::InvalidLength);
        }
        let sig = unsafe { self.sig.as_ref() };
        let func = sig.verify.unwrap();
        let status = unsafe {
            func(
                message.as_ptr(),
                message.len(),
                signature.bytes.as_ptr(),
                signature.len(),
                pk.bytes.as_ptr(),
            )
        };
        status_to_result(status)
    }

    /// Verify a message with a context string
    pub fn verify_with_ctx_str<'a, 'b>(
        &self,
        message: &Message,
        signature: impl Into<SignatureRef<'a>>,
        ctx_str: &CtxStr,
        pk: impl Into<PublicKeyRef<'b>>,
    ) -> Result<()> {
        let signature = signature.into();
        let pk = pk.into();
        if signature.bytes.len() > self.length_signature()
            || pk.bytes.len() != self.length_public_key()
        {
            return Err(Error::InvalidLength);
        }
        let sig = unsafe { self.sig.as_ref() };
        let func = sig.verify_with_ctx_str.unwrap();
        // For algorithms without context string support, liboqs
        // expects the context to be NULL. Converting an empty
        // slice to a pointer doesn't actually do this.
        let ctx_str_ptr = if !ctx_str.is_empty() {
            ctx_str.as_ptr()
        } else {
            null()
        };
        let status = unsafe {
            func(
                message.as_ptr(),
                message.len(),
                signature.bytes.as_ptr(),
                signature.len(),
                ctx_str_ptr,
                ctx_str.len(),
                pk.bytes.as_ptr(),
            )
        };
        status_to_result(status)
    }
}

#[cfg(feature = "rustcrypto")]
/// Signer struct containing a signature scheme and a signing key.
///
/// # Example
/// ```rust
/// # if !cfg!(feature = "ml_dsa") { return; }
/// use oqs;
/// use signature::{Signer,Verifier};
/// oqs::init();
/// let scheme = oqs::sig::Sig::new(oqs::sig::Algorithm::MlDsa44).unwrap();
/// let message = [0u8; 100];
/// let (pk, sk) = scheme.keypair().unwrap();
/// let signer = oqs::sig::Signer::new(&scheme,sk);
/// let verifier = oqs::sig::Verifier::new(&scheme,pk);
/// let signature = signer.try_sign(&message).unwrap();
/// assert!(verifier.verify(&message, &signature).is_ok());
/// ```
#[cfg(feature = "rustcrypto")]
pub struct Signer<'a> {
    scheme: &'a Sig,
    sk: SecretKey,
}

#[cfg(feature = "rustcrypto")]
impl<'a> Signer<'a> {
    /// Creates a new [`Signer`] with the given signature scheme and secret key.
    pub fn new(scheme: &'a Sig, sk: SecretKey) -> Self {
        Signer { scheme, sk }
    }
}

#[cfg(feature = "rustcrypto")]
impl<'a> RustCryptoSigner<sig::Signature> for Signer<'a> {
    fn try_sign(&self, msg: &[u8]) -> core::result::Result<sig::Signature, signature::Error> {
        match self.scheme.sign(msg, &self.sk) {
            Ok(s) => Ok(s),
            Err(_) => Err(signature::Error::new()),
        }
    }
}

#[cfg(feature = "rustcrypto")]
/// Verifier struct containing a signature scheme and a public verification key.
///
/// # Example
/// ```rust
/// # if !cfg!(feature = "ml_dsa") { return; }
/// use oqs;
/// use signature::{Signer,Verifier};
/// oqs::init();
/// let scheme = oqs::sig::Sig::new(oqs::sig::Algorithm::MlDsa44).unwrap();
/// let message = [0u8; 100];
/// let (pk, sk) = scheme.keypair().unwrap();
/// let signer = oqs::sig::Signer::new(&scheme,sk);
/// let verifier = oqs::sig::Verifier::new(&scheme,pk);
/// let signature = signer.try_sign(&message).unwrap();
/// assert!(verifier.verify(&message, &signature).is_ok());
/// ```
///
/// Used to verify signatures for a given message.
#[cfg(feature = "rustcrypto")]
pub struct Verifier<'a> {
    scheme: &'a Sig,
    pk: PublicKey,
}

#[cfg(feature = "rustcrypto")]
impl<'a> Verifier<'a> {
    /// Creates a new [`Verifier`] with the given signature scheme and public key.
    pub fn new(scheme: &'a Sig, pk: PublicKey) -> Self {
        Verifier { scheme, pk }
    }
}

#[cfg(feature = "rustcrypto")]
impl<'a> RustCryptoVerifier<sig::Signature> for Verifier<'a> {
    fn verify(
        &self,
        msg: &[u8],
        signature: &sig::Signature,
    ) -> core::result::Result<(), signature::Error> {
        match self.scheme.verify(msg, signature, &self.pk) {
            Ok(_) => Ok(()),
            Err(_) => Err(signature::Error::new()),
        }
    }
}