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use crate::{
hazmat::{DigestPrimitive, SignPrimitive},
Error, Signature, SignatureSize,
};
use elliptic_curve::{
generic_array::ArrayLength,
ops::Invert,
weierstrass::Curve,
zeroize::{Zeroize, Zeroizing},
Arithmetic, FromBytes, SecretKey,
};
#[cfg(feature = "rand")]
use {
elliptic_curve::Generate,
signature::{
digest::Digest,
rand_core::{CryptoRng, RngCore},
RandomizedDigestSigner, RandomizedSigner,
},
};
pub struct Signer<C>
where
C: Curve + Arithmetic,
C::Scalar: Invert<Output = C::Scalar> + SignPrimitive<C> + Zeroize,
SignatureSize<C>: ArrayLength<u8>,
{
secret_scalar: C::Scalar,
}
impl<C> Signer<C>
where
C: Curve + Arithmetic,
C::Scalar: Invert<Output = C::Scalar> + SignPrimitive<C> + Zeroize,
SignatureSize<C>: ArrayLength<u8>,
{
pub fn new(secret_key: &SecretKey<C>) -> Result<Self, Error> {
let scalar = C::Scalar::from_bytes(secret_key.as_bytes());
if scalar.is_some().into() {
Ok(Self {
secret_scalar: scalar.unwrap(),
})
} else {
Err(Error::new())
}
}
}
#[cfg(feature = "rand")]
#[cfg_attr(docsrs, doc(cfg(feature = "rand")))]
impl<C, D> RandomizedDigestSigner<D, Signature<C>> for Signer<C>
where
C: Curve + Arithmetic,
D: Digest<OutputSize = C::ElementSize>,
C::Scalar: Invert<Output = C::Scalar> + Generate + SignPrimitive<C> + Zeroize,
SignatureSize<C>: ArrayLength<u8>,
{
fn try_sign_digest_with_rng(
&self,
rng: impl CryptoRng + RngCore,
digest: D,
) -> Result<Signature<C>, Error> {
let ephemeral_scalar = Zeroizing::new(C::Scalar::generate(rng));
self.secret_scalar
.try_sign_prehashed(&*ephemeral_scalar, &digest.finalize())
}
}
#[cfg(feature = "rand")]
#[cfg_attr(docsrs, doc(cfg(feature = "rand")))]
impl<C> RandomizedSigner<Signature<C>> for Signer<C>
where
C: Curve + Arithmetic + DigestPrimitive,
C::Digest: Digest<OutputSize = C::ElementSize>,
C::Scalar: Invert<Output = C::Scalar> + Generate + SignPrimitive<C> + Zeroize,
SignatureSize<C>: ArrayLength<u8>,
{
fn try_sign_with_rng(
&self,
rng: impl CryptoRng + RngCore,
msg: &[u8],
) -> Result<Signature<C>, Error> {
self.try_sign_digest_with_rng(rng, C::Digest::new().chain(msg))
}
}
impl<C> Zeroize for Signer<C>
where
C: Curve + Arithmetic,
C::Scalar: Invert<Output = C::Scalar> + SignPrimitive<C> + Zeroize,
SignatureSize<C>: ArrayLength<u8>,
{
fn zeroize(&mut self) {
self.secret_scalar.zeroize();
}
}
impl<C> Drop for Signer<C>
where
C: Curve + Arithmetic,
C::Scalar: Invert<Output = C::Scalar> + SignPrimitive<C> + Zeroize,
SignatureSize<C>: ArrayLength<u8>,
{
fn drop(&mut self) {
self.zeroize();
}
}