BC ML-DSA PKCS#12 KeyStore interoperability issue starting with JDK 24+ #2467

private static final String BC = "BC";

    static {
        Security.addProvider(new BouncyCastleProvider());
    }

    @Test
    void test() throws Exception {

        // -----------------------------------------------------------------
        // 1. Generate ML-DSA key pair using Bouncy Castle
        // -----------------------------------------------------------------

        KeyPairGenerator keyPairGenerator =
                KeyPairGenerator.getInstance("ML-DSA-65", BC);

        KeyPair keyPair = keyPairGenerator.generateKeyPair();

        PrivateKey originalPrivateKey = keyPair.getPrivate();

        System.out.println("=== Original BC key ===");
        System.out.println("Private key class     : "
                + originalPrivateKey.getClass().getName());
        System.out.println("Private key algorithm : "
                + originalPrivateKey.getAlgorithm());
        System.out.println("Private key format    : "
                + originalPrivateKey.getFormat());

        System.out.println("Public key class      : "
                + keyPair.getPublic().getClass().getName());
        System.out.println("Public key algorithm  : "
                + keyPair.getPublic().getAlgorithm());

        // -----------------------------------------------------------------
        // 2. Create an X.509 certificate using Bouncy Castle
        // -----------------------------------------------------------------

        X500Name subject = new X500Name("CN=ML-DSA Test");

        Date notBefore = new Date();
        Date notAfter = new Date(
                notBefore.getTime() + 365L * 24 * 60 * 60 * 1000);

        JcaX509v3CertificateBuilder certificateBuilder =
                new JcaX509v3CertificateBuilder(
                        subject,
                        BigInteger.valueOf(System.currentTimeMillis()),
                        notBefore,
                        notAfter,
                        subject,
                        keyPair.getPublic());

        ContentSigner contentSigner =
                new JcaContentSignerBuilder("ML-DSA-65")
                        .setProvider(BC)
                        .build(keyPair.getPrivate());

        X509Certificate certificate =
                new JcaX509CertificateConverter()
                        .setProvider(BC)
                        .getCertificate(
                                certificateBuilder.build(contentSigner));

        System.out.println("=== BC certificate ===");
        System.out.println("Public key class      : "
                + certificate.getPublicKey().getClass().getName());
        System.out.println("Public key algorithm  : "
                + certificate.getPublicKey().getAlgorithm());

        // this succeeds  (Expected : ML-DSA-65 ; Actual : ML-DSA-65)
        assertEquals(keyPair.getPrivate().getAlgorithm(), certificate.getPublicKey().getAlgorithm());

        // -----------------------------------------------------------------
        // 3. Store to KeyStore using BouncyCastle
        // -----------------------------------------------------------------

        char[] password = "test".toCharArray();

        KeyStore keyStore = KeyStore.getInstance("PKCS12", BC);

        keyStore.load(null, null);

        keyStore.setKeyEntry(
                "test",
                keyPair.getPrivate(),
                password,
                new Certificate[]{certificate});

        ByteArrayOutputStream output = new ByteArrayOutputStream();

        keyStore.store(output, password);

        byte[] pkcs12 = output.toByteArray();

        // -----------------------------------------------------------------
        // 4. Reload using the JDK SUN implementation
        // -----------------------------------------------------------------

        KeyStore reloaded = KeyStore.getInstance("PKCS12", "SUN");

        reloaded.load(
                new ByteArrayInputStream(pkcs12),
                password);

        // -----------------------------------------------------------------
        // 5. Inspect what the JDK reconstructed
        // -----------------------------------------------------------------

        PrivateKey restoredPrivateKey =
                (PrivateKey) reloaded.getKey("test", password);

        X509Certificate restoredCertificate =
                (X509Certificate) reloaded.getCertificate("test");

        System.out.println("=== After KeyStore reloaded with JDK SUN ===");

        System.out.println("Private key class     : "
                + restoredPrivateKey.getClass().getName());

        System.out.println("Private key algorithm : "
                + restoredPrivateKey.getAlgorithm());

        System.out.println("Private key format    : "
                + restoredPrivateKey.getFormat());

        System.out.println("Public key class      : "
                + restoredCertificate.getPublicKey().getClass().getName());

        System.out.println("Public key algorithm  : "
                + restoredCertificate.getPublicKey().getAlgorithm());

        // This fails (Expected : ML-DSA-65 ; Actual : ML-DSA)
        assertEquals(restoredPrivateKey.getAlgorithm(), restoredCertificate.getPublicKey().getAlgorithm());

    }

=== Original BC key ===
Private key class     : org.bouncycastle.jcajce.provider.asymmetric.mldsa.BCMLDSAPrivateKey
Private key algorithm : ML-DSA-65
Private key format    : PKCS#8
Public key class      : org.bouncycastle.jcajce.provider.asymmetric.mldsa.BCMLDSAPublicKey
Public key algorithm  : ML-DSA-65
=== BC certificate ===
Public key class      : org.bouncycastle.jcajce.provider.asymmetric.mldsa.BCMLDSAPublicKey
Public key algorithm  : ML-DSA-65
=== After KeyStore reloaded with JDK SUN ===
Private key class     : org.bouncycastle.jcajce.provider.asymmetric.mldsa.BCMLDSAPrivateKey
Private key algorithm : ML-DSA-65
Private key format    : PKCS#8
Public key class      : sun.security.x509.NamedX509Key
Public key algorithm  : ML-DSA