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+/* -*-c-*-
+ *
+ * The Ed448 signature scheme
+ *
+ * (c) 2017 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of Catacomb.
+ *
+ * Catacomb is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * Catacomb 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 Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with Catacomb; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/*----- Notes on the Ed448 signature scheme -------------------------------*
+ *
+ * This is Ed448, as described in RFC8032, using the EdDSA signature scheme
+ * defined by Daniel J. Bernstein, Neils Duif, Simon Josefsson, Tanja Lange,
+ * Peter Schwabe, and Bo-Yin Yang, `High-speed high-security signatures',
+ * CHES 2011, https://ed25519.cr.yp.to/ed25519-20110926.pdf and `EdDSA for
+ * more curves', http://ed25519.cr.yp.to/eddsa-20150704.pdf.
+ *
+ * This is not the signature scheme described in Hamburg's paper
+ * `Ed448-Goldilocks, a new elliptic curve', EUROCRYPT 2016,
+ * https://eprint.iacr.org/2015/625/, which (a) made use of his `Decaf'
+ * cofactor elimination technique, and (b) was based on Schnorr rather than
+ * EdDSA.
+ *
+ * This code implements the `Ed448' and `Ed448ph' schemes described in
+ * RFC8032, though in the latter case it assumes that you've already done the
+ * hashing and have provided the hash as the `message' input.
+ */
+
+#ifndef CATACOMB_ED448_H
+#define CATACOMB_ED448_H
+
+#ifdef __cplusplus
+  extern "C" {
+#endif
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <mLib/bits.h>
+
+#ifndef CATACOMB_KEY_H
+#  include "key.h"
+#endif
+
+/*----- Important constants -----------------------------------------------*/
+
+#define ED448_KEYSZ 57u
+#define ED448_PUBSZ 57u
+#define ED448_SIGSZ 114u
+
+#define ED448_MAXPERSOSZ 255u
+
+/*----- Key fetching ------------------------------------------------------*/
+
+typedef struct ed448_priv { key_bin priv, pub; } ed448_priv;
+typedef struct ed448_pub { key_bin pub; } ed448_pub;
+
+extern const key_fetchdef ed448_pubfetch[], ed448_privfetch[];
+#define ED448_PUBFETCHSZ 3
+#define ED448_PRIVFETCHSZ 6
+
+/*----- Functions provided ------------------------------------------------*/
+
+/* --- @ed448_pubkey@ --- *
+ *
+ * Arguments:	@octet K[ED448_PUBSZ]@ = where to put the public key
+ *		@const void *k@ = private key
+ *		@size_t ksz@ = length of private key
+ *
+ * Returns:	---
+ *
+ * Use:		Derives the public key from a private key.
+ */
+
+extern void ed448_pubkey(octet /*K*/[ED448_PUBSZ],
+			 const void */*k*/, size_t /*ksz*/);
+
+/* --- @ed448_sign@ --- *
+ *
+ * Arguments:	@octet sig[ED448_SIGSZ]@ = where to put the signature
+ *		@const void *k@ = private key
+ *		@size_t ksz@ = length of private key
+ *		@const octet K[ED448_PUBSZ]@ = public key
+ *		@int phflag@ = whether the `message' has been hashed already
+ *		@const void *p@ = personalization string
+ *		@size_t psz@ = length of personalization string
+ *		@const void *m@ = message to sign
+ *		@size_t msz@ = length of message
+ *
+ * Returns:	---
+ *
+ * Use:		Signs a message.
+ */
+
+extern void ed448_sign(octet /*sig*/[ED448_SIGSZ],
+		       const void */*k*/, size_t /*ksz*/,
+		       const octet /*K*/[ED448_PUBSZ],
+		       int /*phflag*/, const void */*p*/, size_t /*psz*/,
+		       const void */*m*/, size_t /*msz*/);
+
+/* --- @ed448_verify@ --- *
+ *
+ * Arguments:	@const octet K[ED448_PUBSZ]@ = public key
+ *		@const void *m@ = message to sign
+ *		@int phflag@ = whether the `message' has been hashed already
+ *		@const void *p@ = personalization string
+ *		@size_t psz@ = length of personalization string
+ *		@size_t msz@ = length of message
+ *		@const octet sig[ED448_SIGSZ]@ = signature
+ *
+ * Returns:	Zero if OK, negative on failure.
+ *
+ * Use:		Verify a signature.
+ */
+
+extern int ed448_verify(const octet /*K*/[ED448_PUBSZ],
+			int /*phflag*/, const void */*p*/, size_t /*psz*/,
+			const void */*m*/, size_t /*msz*/,
+			const octet /*sig*/[ED448_SIGSZ]);
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+  }
+#endif
+
+#endif