Do not special case export of EC keys

All other private keys are exported in PKCS#8 format, while EC
keys use traditional format. Switch them to use PKCS#8 format as
well.

As the OpenSSL docs say:

> PEM_write_bio_PrivateKey_traditional() writes out a private key
> in the "traditional" format with a simple private key marker and
> should only be used for compatibility with legacy programs.

UPGRADING

@@ -112,6 +112,10 @@ PHP 8.1 UPGRADE NOTES
   . The mysqlnd.fetch_copy_data ini setting has been removed. However, this
     should not result in user-visible behavior changes.
 
+- OpenSSL:
+  . EC private keys will now be exported in PKCS#8 format rather than
+    traditional format, just like all other keys.
+
 - PDO:
   . PDO::ATTR_STRINGIFY_FETCHES now also stringifies values of type bool to
     "0" or "1". Previously booleans were not stringified.

ext/openssl/openssl.c

@@ -4200,21 +4200,9 @@ PHP_FUNCTION(openssl_pkey_export_to_file)
 			cipher = NULL;
 		}
 
-		switch (EVP_PKEY_base_id(key)) {
-#ifdef HAVE_EVP_PKEY_EC
-			case EVP_PKEY_EC:
-				pem_write = PEM_write_bio_ECPrivateKey(
-						bio_out, EVP_PKEY_get0_EC_KEY(key), cipher,
-						(unsigned char *)passphrase, (int)passphrase_len, NULL, NULL);
-				break;
-#endif
-			default:
-				pem_write = PEM_write_bio_PrivateKey(
-						bio_out, key, cipher,
-						(unsigned char *)passphrase, (int)passphrase_len, NULL, NULL);
-				break;
-		}
-
+		pem_write = PEM_write_bio_PrivateKey(
+				bio_out, key, cipher,
+				(unsigned char *)passphrase, (int)passphrase_len, NULL, NULL);
 		if (pem_write) {
 			/* Success!
 			 * If returning the output as a string, do so now */
@@ -4272,21 +4260,9 @@ PHP_FUNCTION(openssl_pkey_export)
 			cipher = NULL;
 		}
 
-		switch (EVP_PKEY_base_id(key)) {
-#ifdef HAVE_EVP_PKEY_EC
-			case EVP_PKEY_EC:
-				pem_write = PEM_write_bio_ECPrivateKey(
-						bio_out, EVP_PKEY_get0_EC_KEY(key), cipher,
-						(unsigned char *)passphrase, (int)passphrase_len, NULL, NULL);
-				break;
-#endif
-			default:
-				pem_write = PEM_write_bio_PrivateKey(
-						bio_out, key, cipher,
-						(unsigned char *)passphrase, (int)passphrase_len, NULL, NULL);
-				break;
-		}
-
+		pem_write = PEM_write_bio_PrivateKey(
+				bio_out, key, cipher,
+				(unsigned char *)passphrase, (int)passphrase_len, NULL, NULL);
 		if (pem_write) {
 			/* Success!
 			 * If returning the output as a string, do so now */

ext/openssl/tests/openssl_pkey_export_basic.phpt

@@ -47,7 +47,11 @@ var_dump($key instanceof OpenSSLAsymmetricKey);
 object(OpenSSLAsymmetricKey)#%d (0) {
 }
 bool(true)
------BEGIN EC PRIVATE KEY-----%a-----END EC PRIVATE KEY-----
+-----BEGIN PRIVATE KEY-----
+MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgs+Sqh7IzteDBiS5K
+PfTvuWuyt9YkrkuoyiW/6bag6NmhRANCAAQ+riFshYe8HnWt1avx6OuNajipU1ZW
+6BgW0+D/EtDDSYeQg9ngO8qyo5M6cyh7ORtKZVUy7DP1+W+eocaZC+a6
+-----END PRIVATE KEY-----
 bool(true)
 bool(true)
 object(OpenSSLAsymmetricKey)#%d (0) {