crypto: add support for Ed25519 context parameter

Signed-off-by: Filip Skokan <panva.ip@gmail.com>

Author: panva

deps/ncrypto/ncrypto.cc

@@ -4333,6 +4333,27 @@ std::optional<EVP_PKEY_CTX*> EVPMDCtxPointer::signInitWithContext(
 #ifdef OSSL_SIGNATURE_PARAM_CONTEXT_STRING
   EVP_PKEY_CTX* ctx = nullptr;
 
+#ifdef OSSL_SIGNATURE_PARAM_INSTANCE
+  // Ed25519 requires the INSTANCE param to switch into Ed25519ctx mode.
+  // Without it, OpenSSL silently ignores the context string.
+  if (key.id() == EVP_PKEY_ED25519) {
+    const OSSL_PARAM params[] = {
+        OSSL_PARAM_construct_utf8_string(
+            OSSL_SIGNATURE_PARAM_INSTANCE, const_cast<char*>("Ed25519ctx"), 0),
+        OSSL_PARAM_construct_octet_string(
+            OSSL_SIGNATURE_PARAM_CONTEXT_STRING,
+            const_cast<unsigned char*>(context_string.data),
+            context_string.len),
+        OSSL_PARAM_END};
+
+    if (!EVP_DigestSignInit_ex(
+            ctx_.get(), &ctx, nullptr, nullptr, nullptr, key.get(), params)) {
+      return std::nullopt;
+    }
+    return ctx;
+  }
+#endif  // OSSL_SIGNATURE_PARAM_INSTANCE
+
   const OSSL_PARAM params[] = {
       OSSL_PARAM_construct_octet_string(
           OSSL_SIGNATURE_PARAM_CONTEXT_STRING,
@@ -4357,6 +4378,27 @@ std::optional<EVP_PKEY_CTX*> EVPMDCtxPointer::verifyInitWithContext(
 #ifdef OSSL_SIGNATURE_PARAM_CONTEXT_STRING
   EVP_PKEY_CTX* ctx = nullptr;
 
+#ifdef OSSL_SIGNATURE_PARAM_INSTANCE
+  // Ed25519 requires the INSTANCE param to switch into Ed25519ctx mode.
+  // Without it, OpenSSL silently ignores the context string.
+  if (key.id() == EVP_PKEY_ED25519) {
+    const OSSL_PARAM params[] = {
+        OSSL_PARAM_construct_utf8_string(
+            OSSL_SIGNATURE_PARAM_INSTANCE, const_cast<char*>("Ed25519ctx"), 0),
+        OSSL_PARAM_construct_octet_string(
+            OSSL_SIGNATURE_PARAM_CONTEXT_STRING,
+            const_cast<unsigned char*>(context_string.data),
+            context_string.len),
+        OSSL_PARAM_END};
+
+    if (!EVP_DigestVerifyInit_ex(
+            ctx_.get(), &ctx, nullptr, nullptr, nullptr, key.get(), params)) {
+      return std::nullopt;
+    }
+    return ctx;
+  }
+#endif  // OSSL_SIGNATURE_PARAM_INSTANCE
+
   const OSSL_PARAM params[] = {
       OSSL_PARAM_construct_octet_string(
           OSSL_SIGNATURE_PARAM_CONTEXT_STRING,

doc/api/crypto.md

@@ -6037,6 +6037,9 @@ Throws an error if FIPS mode is not available.
 <!-- YAML
 added: v12.0.0
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/62474
+    description: Add support for Ed25519 context parameter.
   - version: v24.8.0
     pr-url: https://github.com/nodejs/node/pull/59570
     description: Add support for ML-DSA, Ed448, and SLH-DSA context parameter.
@@ -6100,9 +6103,10 @@ additional properties can be passed:
   `crypto.constants.RSA_PSS_SALTLEN_DIGEST` sets the salt length to the digest
   size, `crypto.constants.RSA_PSS_SALTLEN_MAX_SIGN` (default) sets it to the
   maximum permissible value.
-* `context` {ArrayBuffer|Buffer|TypedArray|DataView} For Ed448, ML-DSA, and SLH-DSA,
-  this option specifies the optional context to differentiate signatures generated
-  for different purposes with the same key.
+* `context` {ArrayBuffer|Buffer|TypedArray|DataView} For Ed25519[^openssl32]
+  (using Ed25519ctx from [RFC 8032][]), Ed448, ML-DSA, and SLH-DSA,
+  this option specifies the optional context to differentiate signatures
+  generated for different purposes with the same key.
 
 If the `callback` function is provided this function uses libuv's threadpool.
 
@@ -6162,6 +6166,9 @@ not introduce timing vulnerabilities.
 <!-- YAML
 added: v12.0.0
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/62474
+    description: Add support for Ed25519 context parameter.
   - version: v24.8.0
     pr-url: https://github.com/nodejs/node/pull/59570
     description: Add support for ML-DSA, Ed448, and SLH-DSA context parameter.
@@ -6231,9 +6238,10 @@ additional properties can be passed:
   `crypto.constants.RSA_PSS_SALTLEN_DIGEST` sets the salt length to the digest
   size, `crypto.constants.RSA_PSS_SALTLEN_MAX_SIGN` (default) sets it to the
   maximum permissible value.
-* `context` {ArrayBuffer|Buffer|TypedArray|DataView} For Ed448, ML-DSA, and SLH-DSA,
-  this option specifies the optional context to differentiate signatures generated
-  for different purposes with the same key.
+* `context` {ArrayBuffer|Buffer|TypedArray|DataView} For Ed25519[^openssl32]
+  (using Ed25519ctx from [RFC 8032][]), Ed448, ML-DSA, and SLH-DSA,
+  this option specifies the optional context to differentiate signatures
+  generated for different purposes with the same key.
 
 The `signature` argument is the previously calculated signature for the `data`.
 
@@ -6832,6 +6840,7 @@ See the [list of SSL OP Flags][] for details.
 [RFC 5208]: https://www.rfc-editor.org/rfc/rfc5208.txt
 [RFC 5280]: https://www.rfc-editor.org/rfc/rfc5280.txt
 [RFC 7517]: https://www.rfc-editor.org/rfc/rfc7517.txt
+[RFC 8032]: https://www.rfc-editor.org/rfc/rfc8032.txt
 [Web Crypto API documentation]: webcrypto.md
 [`BN_is_prime_ex`]: https://www.openssl.org/docs/man1.1.1/man3/BN_is_prime_ex.html
 [`Buffer`]: buffer.md

src/crypto/crypto_sig.cc

@@ -241,6 +241,7 @@ bool SupportsContextString(const EVPKeyPointer& key) {
   return false;
 #else
   switch (key.id()) {
+    case EVP_PKEY_ED25519:
     case EVP_PKEY_ED448:
 #if OPENSSL_WITH_PQC
     case EVP_PKEY_ML_DSA_44: