fix(node): support ECDSA with secp256k1 in node:crypto

[bartlomieju]

Summary

• Adds secp256k1 ECDSA support to node:crypto key generation, signing, verification, and key import/export (DER, PEM, JWK)
• Adds Secp256k1 variant to EcPrivateKey/EcPublicKey enums using the existing k256 crate
• Enables ecdh, jwk, pem features on k256 workspace dependency

Closes #27523

Details

The k256 crate was already used for ECDH with secp256k1, but the ECDSA key generation/signing/verification paths only supported P-224, P-256, and P-384. This PR adds secp256k1 support across all EC code paths:

• Key generation: generateKeyPair('ec', { namedCurve: 'secp256k1' }) now works
• Signing/verification: sign(), verify(), createSign(), createVerify() with secp256k1 keys
• Key import/export: PKCS#8, SEC1, SPKI (DER/PEM), and JWK formats
• Key details: Reports namedCurve: "secp256k1" in asymmetricKeyDetails
• X.509: Parsing secp256k1 public keys from certificates
• DH: diffieHellman() with secp256k1 KeyObject pairs

Test plan

• Added unit tests for key generation, sign/verify (one-shot and streaming), PEM export/import roundtrip, and async key generation
• cargo test unit_node::crypto::crypto_key_test passes

🤖 Generated with Claude Code

[kajukitli]

Good start but incomplete implementation. This PR adds secp256k1 key support but misses critical signing/verification operations.

✅ What works

• Key generation: generateKeyPair('ec', { namedCurve: 'secp256k1' })
• Key import/export: PEM, DER, JWK formats
• ECDH operations (existing support via k256 crate)
• Proper OID handling (1.3.132.0.10)

❌ What's missing

• Signing/verification operations - no secp256k1 case in ext/node_crypto/sign.rs
• sign(), verify(), createSign(), createVerify() will fail at runtime
• Pattern established for P224/P256/P384 but secp256k1 not added

The gap

In ext/node_crypto/sign.rs, the EcPrivateKey match around line 175 is incomplete:

EcPrivateKey::P224(key) => { /* signing logic */ }
EcPrivateKey::P256(key) => { /* signing logic */ } 
EcPrivateKey::P384(key) => { /* signing logic */ }
// EcPrivateKey::Secp256k1(key) => { /* MISSING */ }

Fix needed

Add secp256k1 signing support in sign.rs:

EcPrivateKey::Secp256k1(key) => {
  let signing_key = k256::ecdsa::SigningKey::from(key);
  let signature: k256::ecdsa::Signature = signing_key
    .sign_prehash(digest)
    .map_err(|_| KeyObjectHandlePrehashedSignAndVerifyError::FailedToSignDigest)?;
  dsa_signature(dsa_signature_encoding, signature)
}

Same pattern needed in the verification path for EcPublicKey::Secp256k1.

The k256 crate has the ecdsa feature enabled so the signing types should be available.

Testing

The current tests likely only cover key generation. Need to verify actual sign/verify operations work end-to-end, not just key creation and export.

[bartlomieju]

Thanks for the review! However, the signing/verification support is already implemented in this PR.

sign.rs already has both:

• Signing (line 200): EcPrivateKey::Secp256k1 match arm with k256::ecdsa::SigningKey
• Verification (line 326): EcPublicKey::Secp256k1 match arm with k256::ecdsa::VerifyingKey

The tests also cover actual sign/verify operations end-to-end — not just key generation:

• ec secp256k1 sign and verify — tests sign()/verify() one-shot API
• ec secp256k1 createSign and createVerify — tests streaming API
• ec secp256k1 export and import PEM — tests PEM roundtrip + signing with imported keys

[kajukitli]

Found Node.js compatibility issue with asymmetricKeyDetails

Tested against Node.js and found that Deno returns incorrect curve names in asymmetricKeyDetails.

Current behavior (Deno):

• P-256 → { named_curve: "p256" }
• P-384 → { named_curve: "p384" }
• secp256k1 → { named_curve: "secp256k1" }

Expected behavior (Node.js):

• P-256 → { namedCurve: 'prime256v1' }
• P-384 → { namedCurve: 'secp384r1' }
• secp256k1 → { namedCurve: 'secp256k1' }

Node.js uses OpenSSL standard curve names via OBJ_nid2sn(nid).

Required fix: Update curve name mappings in ext/node_crypto/keys.rs lines 1852-1855 and 1906-1909:

// Lines 1852-1855
let named_curve = match key {
  EcPrivateKey::P224(_) => "secp224r1",    // was "p224"
  EcPrivateKey::P256(_) => "prime256v1",   // was "p256"
  EcPrivateKey::P384(_) => "secp384r1",    // was "p384"
  EcPrivateKey::Secp256k1(_) => "secp256k1", // correct
};

Otherwise this breaks Node.js compatibility for P-224/P-256/P-384 curves.