Oops. Fix formatting. :-S

[u/mdw/catacomb] / group.h

/* -*-c-*-
 *
 * $Id: group.h,v 1.2 2004/04/03 03:32:05 mdw Exp $
 *
 * General cyclic group abstraction
 *
 * (c) 2004 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.
 */

/*----- Revision history --------------------------------------------------* 
 *
 * $Log: group.h,v $
 * Revision 1.2  2004/04/03 03:32:05  mdw
 * General robustification.
 *
 * Revision 1.1  2004/04/01 12:50:09  mdw
 * Add cyclic group abstraction, with test code.  Separate off exponentation
 * functions for better static linking.  Fix a buttload of bugs on the way.
 * Generally ensure that negative exponents do inversion correctly.  Add
 * table of standard prime-field subgroups.  (Binary field subgroups are
 * currently unimplemented but easy to add if anyone ever finds a good one.)
 *
 */

#ifndef CATACOMB_GROUP_H
#define CATACOMB_GROUP_H

#ifdef __cplusplus
  extern "C" {
#endif

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

#include <mLib/dstr.h>

#ifndef CATACOMB_BUF_H
#  include "buf.h"
#endif

#ifndef CATACOMB_DH_H
#  include "ec.h"
#endif

#ifndef CATACOMB_GRAND_H
#  include "grand.h"
#endif

#ifndef CATACOMB_MP_H
#  include "mp.h"
#endif

#ifndef CATACOMB_QDPARSE_H
#  include "qdparse.h"
#endif

/*----- Data structures ---------------------------------------------------*/

#ifndef ge
  typedef struct ge ge;			/* Group element (abstract type) */
#endif

typedef struct group_ {
  const struct group_ops *ops;		/* Operations table */
  size_t nbits;				/* Size of an element in bits */
  size_t noctets;			/* Size of an element in octets */
  ge *i;				/* Identity element */
  ge *g;				/* Generator element */
  mp *r;				/* Order of the generator */
  mp *h;				/* Cofactor */
} group;

typedef struct group_expfactor {
  ge *base;				/* The base */
  mp *exp;				/* The exponent */
} group_expfactor;

typedef struct group_ops {
  unsigned ty;				/* Type of this group */

  /* --- Memory management --- */

  void (*destroygroup)(group */*g*/);
  ge *(*create)(group */*g*/);
  void (*copy)(group */*g*/, ge */*d*/, ge */*x*/);
  void (*burn)(group */*g*/, ge */*x*/);
  void (*destroy)(group */*g*/, ge */*e*/);

  /* --- Comparisons --- */

  int (*samep)(group */*g*/, group */*h*/);
  int (*eq)(group */*g*/, ge */*x*/, ge */*y*/);
  int (*identp)(group */*g*/, ge */*x*/);

  /* --- Other stuff --- */

  const char *(*check)(group */*g*/, grand */*gr*/);

  /* --- Arithmetic --- */

  void (*mul)(group */*g*/, ge */*d*/, ge */*x*/, ge */*y*/);
  void (*sqr)(group */*g*/, ge */*d*/, ge */*x*/);
  void (*inv)(group */*g*/, ge */*d*/, ge */*x*/);
  void (*div)(group */*g*/, ge */*d*/, ge */*x*/, ge */*y*/);
  void (*exp)(group */*g*/, ge */*d*/, ge */*x*/, mp */*n*/);
  void (*mexp)(group */*g*/, ge */*d*/,
	       const group_expfactor */*f*/, size_t /*n*/);

  /* --- Debugging --- */

  int (*read)(group */*g*/, ge */*d*/,
	      const mptext_ops */*ops*/, void */*p*/);
  int (*write)(group */*g*/, ge */*x*/,
	       const mptext_ops */*ops*/, void */*p*/);

  /* --- Conversions --- */

  mp *(*toint)(group */*g*/, mp */*d*/, ge */*x*/);
  int (*fromint)(group */*g*/, ge */*d*/, mp */*x*/);
  int (*toec)(group */*g*/, ec */*d*/, ge */*x*/);
  int (*fromec)(group */*g*/, ge */*d*/, ec */*p*/);
  int (*tobuf)(group */*h*/, buf */*b*/, ge */*x*/);
  int (*frombuf)(group */*h*/, buf */*b*/, ge */*d*/);

} group_ops;

enum {
  GTY_PRIME,				/* Prime field subgroup */
  GTY_BINARY,				/* Binary feld subgroup */
  GTY_EC				/* Elliptic curve group */
};

#define G_DESTROYGROUP(g)	(g)->ops->destroygroup((g))
#define G_CREATE(g)		(g)->ops->create((g))
#define G_COPY(g, d, x)		(g)->ops->copy((g), (d), (x))
#define G_BURN(g, x)		(g)->ops->burn((g), (x))
#define G_DESTROY(g, x)		(g)->ops->destroy((g), (x))

#define G_SAMEP(g, h)		(g)->ops->samep((g), (h))
#define G_EQ(g, x, y)		(g)->ops->eq((g), (x), (y))
#define G_IDENTP(g, x)		(g)->ops->identp((g), (x))

#define G_CHECK(g, gr)		(g)->ops->check((g), (gr))

#define G_MUL(g, d, x, y)	(g)->ops->mul((g), (d), (x), (y))
#define G_SQR(g, d, x)		(g)->ops->sqr((g), (d), (x))
#define G_INV(g, d, x)		(g)->ops->inv((g), (d), (x))
#define G_DIV(g, d, x, y)	(g)->ops->div((g), (d), (x), (y))
#define G_EXP(g, d, x, n)	(g)->ops->exp((g), (d), (x), (n))
#define G_MEXP(g, d, f, n)	(g)->ops->mexp((g), (d), (f), (n))

#define G_READ(g, d, o, p)	(g)->ops->read((g), (d), (o), (p))
#define G_WRITE(g, x, o, p)	(g)->ops->write((g), (x), (o), (p))

#define G_TOINT(g, d, x)	(g)->ops->toint((g), (d), (x))
#define G_FROMINT(g, d, x)	(g)->ops->fromint((g), (d), (x))
#define G_TOEC(g, d, x)		(g)->ops->toec((g), (d), (x))
#define G_FROMEC(g, d, p)	(g)->ops->fromec((g), (d), (p))
#define G_TOBUF(g, b, x)	(g)->ops->tobuf((g), (b), (x))
#define G_FROMBUF(g, b, d)	(g)->ops->frombuf((g), (b), (d))

/*----- Handy functions ---------------------------------------------------*/

/* --- @group_check@ --- *
 *
 * Arguments:	@group *g@ = an abstract group
 *		@ge *x@ = a group element
 *
 * Returns:	Zero on success, nonzero for failure.
 *
 * Use:		Checks that @x@ is a valid group element.  This may take a
 *		while, since it checks that %$x^h \ne 1$%.
 */

extern int group_check(group */*g*/, ge */*x*/);

/* --- @group_samep@ --- *
 *
 * Arguments:	@group *g, *h@ = two abstract groups
 *
 * Returns:	Nonzero if the groups are in fact identical (not just
 *		isomorphic).
 *
 * Use:		Checks to see whether two groups are actually the same.  This
 *		function does the full check: the group operatrion @samep@
 *		just does the group-specific details.
 */

extern int group_samep(group */*g*/, group */*h*/);

/*----- Textual I/O on group elements -------------------------------------*/

extern int group_readstring(group */*g*/, ge */*d*/,
			    const char */*p*/, char **/*end*/);
extern int group_writestring(group */*g*/, ge */*d*/,
			     char */*p*/, size_t /*sz*/);

extern int group_readfile(group */*g*/, ge */*d*/, FILE */*fp*/);
extern int group_writefile(group */*g*/, ge */*x*/, FILE */*fp*/);

extern int group_readdstr(group */*g*/, ge */*d*/,
			  dstr */*dd*/, size_t */*off*/);
extern int group_writedstr(group */*g*/, ge */*x*/, dstr */*d*/);

/*----- Standard implementations ------------------------------------------*/

/* --- @group_stdidentp@ --- *
 *
 * Arguments:	@group *g@ = abstract group
 *		@ge *x@ = group element
 *
 * Returns:	Nonzero if %$x$% is the group identity.
 */

extern int group_stdidentp(group */*g*/, ge */*x*/);

/* --- @group_stdcheck@ --- *
 *
 * Arguments:	@group *g@ = abstract group
 *		@grand *gr@ = random number source.
 *
 * Returns:	Null on success, or a pointer to an error message.
 */

extern const char *group_stdcheck(group */*g*/, grand */*gr*/);

/* --- @group_stdsqr@ --- *
 *
 * Arguments:	@group *g@ = abstract group
 *		@ge *d@ = destination pointer
 *		@ge *x@ = group element
 *
 * Returns:	---
 *
 * Use:		Computes %$d = x^2$% as %$d = x x$%.
 */

extern void group_stdsqr(group */*g*/, ge */*d*/, ge */*x*/);

/* --- @group_stddiv@ --- *
 *
 * Arguments:	@group *g@ = abstract group
 *		@ge *d@ = destination pointer
 *		@ge *x@ = dividend
 *		@ge *y@ = divisor
 *
 * Returns:	---
 *
 * Use:		Computes %$d = x/y$% as %$d = x y^{-1}$%.
 */

extern void group_stddiv(group */*g*/, ge */*d*/, ge */*x*/, ge */*y*/);

/* --- @group_stdexp@ --- *
 *
 * Arguments:	@group *g@ = abstract group
 *		@ge *d@ = destination pointer
 *		@ge *x@ = base element
 *		@mp *n@ = exponent
 *
 * Returns:	---
 *
 * Use:		Computes %$d = x^n$% efficiently.
 */

extern void group_stdexp(group */*g*/, ge */*d*/, ge */*x*/, mp */*n*/);

/* --- @group_stdmexp@ --- *
 *
 * Arguments:	@group *g@ = abstract group
 *		@ge *d@ = destination pointer
 *		@const group_expfactor *f@ = vector of factors
 *		@size_t n@ = number of factors
 *
 * Returns:	---
 *
 * Use:		Computes %$d = g_0^{x_0} g_1^{x_1} \ldots$% efficiently.
 */

extern void group_stdmexp(group */*g*/, ge */*d*/,
			  const group_expfactor */*f*/, size_t /*n*/);

/* --- @group_stdtoec@ --- *
 *
 * Arguments:	@group *g@ = abstract group
 *		@ec *d@ = destination point
 *		@ge *x@ = group element
 *
 * Returns:	@-1@, indicating failure.
 *
 * Use:		Fails to convert a group element to an elliptic curve point.
 */

extern int group_stdtoec(group */*g*/, ec */*d*/, ge */*x*/);

/* --- @group_stdfromec@ --- *
 *
 * Arguments:	@group *g@ = abstract group
 *		@ge *d@ = destination pointer
 *		@ec *p@ = elliptic curve point
 *
 * Returns:	Zero for success, @-1@ on failure.
 *
 * Use:		Converts %$p$% to a group element by converting its %$x$%-
 *		coordinate.
 */

extern int group_stdfromec(group */*g*/, ge */*d*/, ec */*p*/);

/*----- Prime field subgroups ---------------------------------------------*/

typedef struct gprime_param {
  mp *p, *q;				/* Prime numbers %$p$% and %$q$% */
  mp *g;				/* Generates order-%$q$% subgroup */
} gprime_param;

/* --- @group_prime@ --- *
 *
 * Arguments:	@const gprime_param *gp@ = group parameters
 *
 * Returns:	A pointer to the group, or null.
 *
 * Use:		Constructs an abstract group interface for a subgroup of a
 *		prime field.  Group elements are @mp *@ pointers.
 */

group *group_prime(const gprime_param */*gp*/);

/*----- Elliptic curve groups ---------------------------------------------*/

/* --- @group_ec@ --- *
 *
 * Arguments:	@const ec_info *ei@ = elliptic curve parameters
 *
 * Returns:	A pointer to the group, or null.
 *
 * Use:		Constructs an abstract group interface for an elliptic curve
 *		group.  Group elements are @ec@ structures.  The contents of
 *		the @ec_info@ structure becomes the property of the @group@
 *		object; you can (and should) free the structure itself, but
 *		calling @ec_freeinfo@ on it is not allowed.
 */

group *group_ec(const ec_info */*ei*/);

/*----- General group initialization --------------------------------------*/

/* --- @group_parse@ --- *
 *
 * Arguments:	@qd_parse *qd@ = quick-and-dirty parser
 *
 * Returns:	Group pointer, or null for failure.
 *
 * Use:		Parses a group description and returns the group.  This has
 *		the form `TYPE { SPEC }' where TYPE is `prime' or `ec', and
 *		SPEC is the appropriate kind of group specification of the
 *		given type.
 */

extern group *group_parse(qd_parse */*qd*/);

/* --- @group_fromstring@ --- *
 *
 * Arguments:	@const char *p@ = pointer to string to read
 *		@group **gg@ = where to put the group pointer
 *
 * Returns:	Null if OK, or an error string.
 *
 * Use:		Parses a group spec from a string, and returns the group.
 */

extern const char *group_fromstring(const char */*p*/, group **/*gg*/);

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

#ifdef __cplusplus
  }
#endif

#endif