[crypto] Add X25519 OID-identified algorithm and TLS named curve

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/config/config_crypto.c

@@ -83,6 +83,11 @@ REQUIRE_OBJECT ( oid_sha512_224 );
 REQUIRE_OBJECT ( oid_sha512_256 );
 #endif
 
+/* X25519 */
+#if defined ( CRYPTO_CURVE_X25519 )
+REQUIRE_OBJECT ( oid_x25519 );
+#endif
+
 /* RSA and MD5 */
 #if defined ( CRYPTO_PUBKEY_RSA ) && defined ( CRYPTO_DIGEST_MD5 )
 REQUIRE_OBJECT ( rsa_md5 );

src/config/crypto.h

@@ -48,6 +48,9 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 /** SHA-512/256 digest algorithm */
 //#define CRYPTO_DIGEST_SHA512_256
 
+/** X25519 elliptic curve */
+#define CRYPTO_CURVE_X25519
+
 /** Margin of error (in seconds) allowed in signed timestamps
  *
  * We default to allowing a reasonable margin of error: 12 hours to

src/crypto/mishmash/oid_x25519.c

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2024 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <byteswap.h>
+#include <ipxe/x25519.h>
+#include <ipxe/asn1.h>
+#include <ipxe/tls.h>
+
+/** "x25519" object identifier */
+static uint8_t oid_x25519[] = { ASN1_OID_X25519 };
+
+/** "x25519" OID-identified algorithm */
+struct asn1_algorithm x25519_algorithm __asn1_algorithm = {
+	.name = "x25519",
+	.curve = &x25519_curve,
+	.oid = ASN1_CURSOR ( oid_x25519 ),
+};
+
+/** X25519 named curve */
+struct tls_named_curve tls_x25519_named_curve __tls_named_curve ( 01 ) = {
+	.curve = &x25519_curve,
+	.code = htons ( TLS_NAMED_CURVE_X25519 ),
+};

src/include/ipxe/asn1.h

@@ -187,6 +187,11 @@ struct asn1_builder_header {
 	ASN1_OID_SINGLE ( 3 ), ASN1_OID_SINGLE ( 2 ),		\
 	ASN1_OID_SINGLE ( 26 )
 
+/** ASN.1 OID for id-x25519 (1.3.101.110) */
+#define ASN1_OID_X25519						\
+	ASN1_OID_INITIAL ( 1, 3 ), ASN1_OID_SINGLE ( 101 ),	\
+	ASN1_OID_SINGLE ( 110 )
+
 /** ASN.1 OID for id-sha256 (2.16.840.1.101.3.4.2.1) */
 #define ASN1_OID_SHA256						\
 	ASN1_OID_INITIAL ( 2, 16 ), ASN1_OID_DOUBLE ( 840 ),	\
@@ -312,6 +317,8 @@ struct asn1_algorithm {
 	struct pubkey_algorithm *pubkey;
 	/** Digest algorithm (if applicable) */
 	struct digest_algorithm *digest;
+	/** Elliptic curve (if applicable) */
+	struct elliptic_curve *curve;
 };
 
 /** ASN.1 OID-identified algorithms */