fix(core): add attestation sig validation

crates/core/src/attestation.rs

@@ -46,6 +46,7 @@ use crate::{
     index::Index,
     merkle::MerkleTree,
     presentation::PresentationBuilder,
+    serialize::CanonicalSerialize,
     signing::{Signature, VerifyingKey},
     transcript::{encoding::EncodingCommitment, hash::PlaintextHash},
     CryptoProvider,
@@ -263,7 +264,7 @@ impl Body {
 /// An attestation document.
 ///
 /// See [module level documentation](crate::attestation) for more information.
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone, Deserialize, Serialize)]
 pub struct Attestation {
     /// The signature of the attestation.
     pub signature: Signature,
@@ -286,4 +287,86 @@ impl Attestation {
     ) -> PresentationBuilder<'a> {
         PresentationBuilder::new(provider, self)
     }
+
+    /// Validates the `unchecked` attestation, returning a validated one.
+    pub fn try_from_unchecked(
+        unchecked: AttestationUnchecked,
+        provider: &CryptoProvider,
+    ) -> Result<Attestation, InvalidAttestation> {
+        let verifier = provider
+            .signature
+            .get(&unchecked.signature.alg)
+            .map_err(|_| {
+                InvalidAttestation(format!(
+                    "invalid signature algorithm id {:?}",
+                    unchecked.signature.alg
+                ))
+            })?;
+
+        verifier
+            .verify(
+                &unchecked.body.verifying_key.data,
+                &CanonicalSerialize::serialize(&unchecked.header),
+                &unchecked.signature.data,
+            )
+            .map_err(|_| InvalidAttestation("failed to verify the signature".into()))?;
+
+        Ok(Self {
+            body: unchecked.body,
+            header: unchecked.header,
+            signature: unchecked.signature,
+        })
+    }
+}
+
+#[doc(hidden)]
+#[derive(Debug, Deserialize)]
+#[serde(from = "Attestation")]
+pub struct AttestationUnchecked {
+    signature: Signature,
+    header: Header,
+    body: Body,
+}
+
+impl From<Attestation> for AttestationUnchecked {
+    fn from(attestation: Attestation) -> Self {
+        Self {
+            body: attestation.body,
+            header: attestation.header,
+            signature: attestation.signature,
+        }
+    }
+}
+
+/// Invalid attestation error.
+#[derive(Debug, thiserror::Error)]
+#[error("invalid attestation: {0}")]
+pub struct InvalidAttestation(String);
+
+#[cfg(test)]
+mod tests {
+    use crate::{
+        attestation::{Attestation, AttestationUnchecked},
+        fixtures::basic_attestation_fixture,
+    };
+
+    #[test]
+    fn test_validation_ok() {
+        let (attestation, provider) = basic_attestation_fixture();
+        let unchecked: AttestationUnchecked = attestation.into();
+        let result = Attestation::try_from_unchecked(unchecked, &provider);
+        assert!(result.is_ok());
+    }
+
+    #[test]
+    fn test_validation_err() {
+        let (mut attestation, provider) = basic_attestation_fixture();
+
+        // Corrupt the signature.
+        attestation.signature.data[1] = attestation.signature.data[1].wrapping_add(1);
+
+        let unchecked: AttestationUnchecked = attestation.into();
+        let result = Attestation::try_from_unchecked(unchecked, &provider);
+        assert!(result.is_err());
+    }
 }

crates/core/src/fixtures.rs

@@ -6,14 +6,15 @@ pub use provider::FixtureEncodingProvider;
 
 use hex::FromHex;
 use p256::ecdsa::SigningKey;
+use tlsn_data_fixtures::http::{request::GET_WITH_HEADER, response::OK_JSON};
 
 use crate::{
     attestation::{Attestation, AttestationConfig, Extension},
     connection::{
         Certificate, ConnectionInfo, HandshakeData, HandshakeDataV1_2, KeyType, ServerCertData,
         ServerEphemKey, ServerName, ServerSignature, SignatureScheme, TlsVersion, TranscriptLength,
     },
-    hash::HashAlgorithm,
+    hash::{Blake3, HashAlgorithm},
     request::{Request, RequestConfig},
     signing::SignatureAlgId,
     transcript::{
@@ -222,13 +223,13 @@ pub fn request_fixture(
     }
 }
 
-/// Returns an attestation fixture for testing.
+/// Returns an attestation fixture and a crypto provider for testing.
 pub fn attestation_fixture(
     request: Request,
     connection: ConnectionFixture,
     signature_alg: SignatureAlgId,
     secret: EncoderSecret,
-) -> Attestation {
+) -> (Attestation, CryptoProvider) {
     let ConnectionFixture {
         connection_info,
         server_cert_data,
@@ -261,5 +262,30 @@ pub fn attestation_fixture(
         .server_ephemeral_key(server_ephemeral_key)
         .encoder_secret(secret);
 
-    attestation_builder.build(&provider).unwrap()
+    (attestation_builder.build(&provider).unwrap(), provider)
+}
+
+/// Returns a basic attestation fixture and a crypto provider for testing.
+pub fn basic_attestation_fixture() -> (Attestation, CryptoProvider) {
+    let transcript = Transcript::new(GET_WITH_HEADER, OK_JSON);
+    let connection = ConnectionFixture::tlsnotary(transcript.length());
+
+    let RequestFixture {
+        mut request,
+        encoding_tree: _,
+    } = request_fixture(
+        transcript.clone(),
+        encoding_provider(GET_WITH_HEADER, OK_JSON),
+        connection.clone(),
+        Blake3::default(),
+        Vec::new(),
+    );
+
+    request.encoding_commitment_root = None;
+    attestation_fixture(
+        request,
+        connection,
+        SignatureAlgId::SECP256K1,
+        encoder_secret(),
+    )
 }

crates/core/src/request.rs

@@ -129,7 +129,7 @@ mod test {
             Vec::new(),
         );
 
-        let attestation = attestation_fixture(
+        let (attestation, _) = attestation_fixture(
             request.clone(),
             connection,
             SignatureAlgId::SECP256K1,
@@ -152,7 +152,7 @@ mod test {
             Vec::new(),
         );
 
-        let attestation = attestation_fixture(
+        let (attestation, _) = attestation_fixture(
             request.clone(),
             connection,
             SignatureAlgId::SECP256K1,
@@ -178,7 +178,7 @@ mod test {
             Vec::new(),
         );
 
-        let attestation = attestation_fixture(
+        let (attestation, _) = attestation_fixture(
             request.clone(),
             connection,
             SignatureAlgId::SECP256K1,
@@ -204,7 +204,7 @@ mod test {
             Vec::new(),
         );
 
-        let attestation = attestation_fixture(
+        let (attestation, _) = attestation_fixture(
             request.clone(),
             connection,
             SignatureAlgId::SECP256K1,
@@ -240,7 +240,7 @@ mod test {
             Vec::new(),
         );
 
-        let attestation = attestation_fixture(
+        let (attestation, _) = attestation_fixture(
             request.clone(),
             connection,
             SignatureAlgId::SECP256K1,

crates/core/src/transcript/proof.rs

@@ -507,14 +507,13 @@ mod tests {
         let transcript_proof = builder.build().unwrap();
 
         request.encoding_commitment_root = None;
-        let attestation = attestation_fixture(
+        let (attestation, provider) = attestation_fixture(
             request,
             connection,
             SignatureAlgId::SECP256K1,
             encoder_secret(),
         );
 
-        let provider = CryptoProvider::default();
         let err = transcript_proof
             .verify_with_provider(&provider, &attestation.body)
             .err()

crates/prover/src/notarize.rs

@@ -7,7 +7,7 @@ use super::{state::Notarize, Prover, ProverError};
 use serio::{stream::IoStreamExt as _, SinkExt as _};
 use tlsn_common::encoding;
 use tlsn_core::{
-    attestation::Attestation,
+    attestation::{Attestation, AttestationUnchecked},
     request::{Request, RequestConfig},
     transcript::{encoding::EncodingTree, Transcript, TranscriptCommitConfig},
     Secrets,
@@ -95,7 +95,9 @@ impl Prover<Notarize> {
 
                 ctx.io_mut().send(request.clone()).await?;
 
-                let attestation: Attestation = ctx.io_mut().expect_next().await?;
+                let unchecked: AttestationUnchecked = ctx.io_mut().expect_next().await?;
+                let attestation = Attestation::try_from_unchecked(unchecked, provider)
+                    .map_err(ProverError::attestation)?;
 
                 Ok::<_, ProverError>(attestation)
             })