ec-field-test.c: Make the field-element type use internal format.

[secnet] / ed25519.h

/* -*-c-*-
 *
 * The Ed25519 signature scheme
 *
 * (c) 2017 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------*
 *
 * This file is part of secnet.
 * See README for full list of copyright holders.
 *
 * secnet 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 d of the License, or
 * (at your option) any later version.
 *
 * secnet 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
 * version 3 along with secnet; if not, see
 * https://www.gnu.org/licenses/gpl.html.
 *
 * This file was originally part of Catacomb, but has been automatically
 * modified for incorporation into secnet: see `import-catacomb-crypto'
 * for details.
 *
 * 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.
 */

#ifndef CATACOMB_ED25519_H
#define CATACOMB_ED25519_H

#ifdef __cplusplus
  extern "C" {
#endif

/*----- Notes on the Ed25519 signature scheme -----------------------------*
 *
 * This is Ed25519, as described in Daniel J. Bernstein, Neils Duif, Tanja
 * Lange, Peter Schwabe, and Bo-Yin Yang, `High-speed high-security
 * signatures', CHES 2011, https://ed25519.cr.yp.to/ed25519-20110926.pdf
 *
 * Specifically, this code implements `PureEdDSA', according to the
 * definition in Daniel J. Bernstein, Simon Josefsson, Tanja Lange, Peter
 * Schwabe, and Bo-Yin Yang, `EdDSA for more curves',
 * https://ed25519.cr.yp.to/eddsa-20150704.pdf.  HashEdEDSA can be
 * implemented easily by presenting a hash of a message to the functions
 * here, as the message to be signed or verified.
 *
 * It also implements `Ed25519ctx' and `Ed25519ph' as 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.
 */

/*----- Header files ------------------------------------------------------*/

#include "fake-mLib-bits.h"

/*----- Important constants -----------------------------------------------*/

#define ED25519_KEYSZ 32u
#define ED25519_PUBSZ 32u
#define ED25519_SIGSZ 64u

#define ED25519_MAXPERSOSZ 255u

/*----- Functions provided ------------------------------------------------*/

/* --- @ed25519_pubkey@ --- *
 *
 * Arguments:	@octet K[ED25519_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 ed25519_pubkey(octet /*K*/[ED25519_PUBSZ],
			   const void */*k*/, size_t /*ksz*/);

/* --- @ed25519_sign@, @ed25519ctx_sign@ --- *
 *
 * Arguments:	@octet sig[ED25519_SIGSZ]@ = where to put the signature
 *		@const void *k@ = private key
 *		@size_t ksz@ = length of private key
 *		@const octet K[ED25519_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.
 *
 *		In @ed25519ctx_sign@, if @phflag@ is @-1@ then you get plain
 *		old Ed25519: the personalization string pointer @p@ will be
 *		ignored.  If @phflag > 0@ then the `message' @m@ should be a
 *		SHA512 hash of the actual message.
 */

extern void ed25519ctx_sign(octet /*sig*/[ED25519_SIGSZ],
			    const void */*k*/, size_t /*ksz*/,
			    const octet /*K*/[ED25519_PUBSZ],
			    int /*phflag*/,
			    const void */*p*/, size_t /*psz*/,
			    const void */*m*/, size_t /*msz*/);

extern void ed25519_sign(octet /*sig*/[ED25519_SIGSZ],
			 const void */*k*/, size_t /*ksz*/,
			 const octet /*K*/[ED25519_PUBSZ],
			 const void */*m*/, size_t /*msz*/);

/* --- @ed25519_verify@, @ed25519ctx_verify@ --- *
 *
 * Arguments:	@const octet K[ED25519_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
 *		@const octet sig[ED25519_SIGSZ]@ = signature
 *
 * Returns:	Zero if OK, negative on failure.
 *
 * Use:		Verify a signature.
 *
 *		In @ed25519ctx_verify@, if @phflag@ is @-1@ then you get
 *		plain old Ed25519: the personalization string pointer @p@
 *		will be ignored.  If @phflag > 0@ then the `message' @m@
 *		should be a SHA512 hash of the actual message.
 */

extern int ed25519ctx_verify(const octet /*K*/[ED25519_PUBSZ],
			     int /*phflag*/,
			     const void */*p*/, size_t /*psz*/,
			     const void */*m*/, size_t /*msz*/,
			     const octet /*sig*/[ED25519_SIGSZ]);

extern int ed25519_verify(const octet /*K*/[ED25519_PUBSZ],
			  const void */*m*/, size_t /*msz*/,
			  const octet /*sig*/[ED25519_SIGSZ]);

/*----- That's all, folks -------------------------------------------------*/

#ifdef __cplusplus
  }
#endif

#endif