adds a signature::Signer implementation for ecc keys

Signed-off-by: Arthur Gautier <arthur.gautier@arista.com>

tss-esapi/Cargo.toml

@@ -42,6 +42,7 @@ sha3 = { version = "0.10.8", optional = true }
 sm2 = { version = "0.13.3", optional = true }
 sm3 = { version = "0.4.2", optional = true }
 digest = "0.10.7"
+signature = "2.2.0"
 cfg-if = "1.0.0"
 strum = { version = "0.25.0", optional = true }
 strum_macros = { version = "0.25.0", optional = true }

tss-esapi/src/abstraction/transient/mod.rs

@@ -34,8 +34,10 @@ use std::convert::{AsMut, AsRef, TryFrom, TryInto};
 use zeroize::Zeroize;
 
 mod key_attestation;
+mod signer;
 
 pub use key_attestation::MakeCredParams;
+pub use signer::Ecdsa;
 
 /// Parameters for the kinds of keys supported by the context
 #[derive(Debug, Clone, Copy)]

tss-esapi/src/abstraction/transient/signer.rs

@@ -0,0 +1,170 @@
+// Copyright 2024 Contributors to the Parsec project.
+// SPDX-License-Identifier: Apache-2.0
+
+//! Module for exposing a [`signature::Signer`] interface for keys
+//!
+//! This modules presents objects held in a TPM over a [`signature::DigestSigner`] interface.
+use super::TransientKeyContext;
+use crate::{
+    abstraction::{
+        public::AssociatedTpmCurve,
+        transient::{KeyMaterial, KeyParams},
+        AssociatedHashingAlgorithm,
+    },
+    interface_types::algorithm::EccSchemeAlgorithm,
+    structures::{Auth, Digest as TpmDigest, EccScheme, Signature as TpmSignature},
+    Error,
+};
+
+use std::{convert::TryFrom, ops::Add, sync::Mutex};
+
+use digest::{Digest, FixedOutput, Output};
+use ecdsa::{
+    der::{MaxOverhead, MaxSize, Signature as DerSignature},
+    hazmat::{DigestPrimitive, SignPrimitive},
+    Signature, SignatureSize, VerifyingKey,
+};
+use elliptic_curve::{
+    generic_array::ArrayLength,
+    ops::Invert,
+    sec1::{FromEncodedPoint, ModulusSize, ToEncodedPoint},
+    subtle::CtOption,
+    AffinePoint, CurveArithmetic, FieldBytesSize, PrimeCurve, PublicKey, Scalar,
+};
+use signature::{DigestSigner, Error as SigError, KeypairRef};
+
+#[derive(Debug)]
+pub struct Ecdsa<'ctx, C>
+where
+    C: PrimeCurve + CurveArithmetic,
+{
+    context: Mutex<&'ctx mut TransientKeyContext>,
+    key_material: KeyMaterial,
+    key_auth: Option<Auth>,
+    verifying_key: VerifyingKey<C>,
+}
+
+impl<'ctx, C> Ecdsa<'ctx, C>
+where
+    C: PrimeCurve + CurveArithmetic,
+    C: AssociatedTpmCurve,
+    FieldBytesSize<C>: ModulusSize,
+    AffinePoint<C>: FromEncodedPoint<C> + ToEncodedPoint<C>,
+{
+    pub fn new(
+        context: &'ctx mut TransientKeyContext,
+        key_material: KeyMaterial,
+        key_auth: Option<Auth>,
+    ) -> Result<Self, Error> {
+        let context = Mutex::new(context);
+
+        let public_key = PublicKey::try_from(key_material.public())?;
+        let verifying_key = VerifyingKey::from(public_key);
+
+        Ok(Self {
+            context,
+            key_material,
+            key_auth,
+            verifying_key,
+        })
+    }
+}
+
+impl<'ctx, C> Ecdsa<'ctx, C>
+where
+    C: PrimeCurve + CurveArithmetic,
+    C: AssociatedTpmCurve,
+{
+    /// Key parameters for this curve
+    pub fn key_params_default() -> KeyParams
+    where
+        C: DigestPrimitive,
+        <C as DigestPrimitive>::Digest: AssociatedHashingAlgorithm,
+    {
+        Self::key_params::<C::Digest>()
+    }
+
+    /// Key parameters for this curve
+    pub fn key_params<D>() -> KeyParams
+    where
+        D: AssociatedHashingAlgorithm,
+    {
+        KeyParams::Ecc {
+            curve: C::TPM_CURVE,
+            scheme: EccScheme::create(EccSchemeAlgorithm::EcDsa, Some(D::TPM_DIGEST), None)
+                .expect("Failed to create ecc scheme"),
+        }
+    }
+}
+
+impl<'ctx, C> AsRef<VerifyingKey<C>> for Ecdsa<'ctx, C>
+where
+    C: PrimeCurve + CurveArithmetic,
+    Scalar<C>: Invert<Output = CtOption<Scalar<C>>> + SignPrimitive<C>,
+    SignatureSize<C>: ArrayLength<u8>,
+{
+    fn as_ref(&self) -> &VerifyingKey<C> {
+        &self.verifying_key
+    }
+}
+
+impl<'ctx, C> KeypairRef for Ecdsa<'ctx, C>
+where
+    C: PrimeCurve + CurveArithmetic,
+    Scalar<C>: Invert<Output = CtOption<Scalar<C>>> + SignPrimitive<C>,
+    SignatureSize<C>: ArrayLength<u8>,
+{
+    type VerifyingKey = VerifyingKey<C>;
+}
+
+impl<'ctx, C, D> DigestSigner<D, Signature<C>> for Ecdsa<'ctx, C>
+where
+    C: PrimeCurve + CurveArithmetic + DigestPrimitive,
+    C: AssociatedTpmCurve,
+    D: Digest + FixedOutput<OutputSize = FieldBytesSize<C>>,
+    D: AssociatedHashingAlgorithm,
+    Scalar<C>: Invert<Output = CtOption<Scalar<C>>> + SignPrimitive<C>,
+    SignatureSize<C>: ArrayLength<u8>,
+    TpmDigest: From<Output<D>>,
+{
+    fn try_sign_digest(&self, digest: D) -> Result<Signature<C>, SigError> {
+        let digest = TpmDigest::from(digest.finalize_fixed());
+
+        let key_params = Self::key_params::<D>();
+        let mut context = self.context.lock().expect("Mutex got poisoned");
+        let signature = context
+            .sign(
+                self.key_material.clone(),
+                key_params,
+                self.key_auth.clone(),
+                digest,
+            )
+            .map_err(SigError::from_source)?;
+        let TpmSignature::EcDsa(signature) = signature else {
+            todo!();
+        };
+
+        let signature = Signature::try_from(signature).map_err(SigError::from_source)?;
+
+        Ok(signature)
+    }
+}
+
+impl<'ctx, C, D> DigestSigner<D, DerSignature<C>> for Ecdsa<'ctx, C>
+where
+    C: PrimeCurve + CurveArithmetic + DigestPrimitive,
+    C: AssociatedTpmCurve,
+    D: Digest + FixedOutput<OutputSize = FieldBytesSize<C>>,
+    D: AssociatedHashingAlgorithm,
+    Scalar<C>: Invert<Output = CtOption<Scalar<C>>> + SignPrimitive<C>,
+    SignatureSize<C>: ArrayLength<u8>,
+    TpmDigest: From<Output<D>>,
+
+    MaxSize<C>: ArrayLength<u8>,
+    <FieldBytesSize<C> as Add>::Output: Add<MaxOverhead> + ArrayLength<u8>,
+{
+    fn try_sign_digest(&self, digest: D) -> Result<DerSignature<C>, SigError> {
+        let signature: Signature<_> = self.try_sign_digest(digest)?;
+        Ok(signature.to_der())
+    }
+}