[u/mdw/catacomb] / group.h

/* -*-c-*-
 *
 * $Id: group.h,v 1.5 2004/04/17 09:58:37 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.
 */

#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 raw 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*/, const ec */*p*/);
  int (*tobuf)(group */*h*/, buf */*b*/, ge */*x*/);
  int (*frombuf)(group */*h*/, buf */*b*/, ge */*d*/);
  int (*toraw)(group */*h*/, buf */*b*/, ge */*x*/);
  int (*fromraw)(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))
#define G_TORAW(g, b, x)	(g)->ops->toraw((g), (b), (x))
#define G_FROMRAW(g, b, d)	(g)->ops->fromraw((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
 *		@const 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*/, const 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
Commit	Line	Data
34e4f738	1	/* --c--
34e4f738	2	*
5c3f75ec	3	* $Id: group.h,v 1.5 2004/04/17 09:58:37 mdw Exp $
34e4f738	4	*
	5	* General cyclic group abstraction
	6	*
	7	* (c) 2004 Straylight/Edgeware
	8	*/
	9
	10	/----- Licensing notice --------------------------------------------------
	11	*
	12	* This file is part of Catacomb.
	13	*
	14	* Catacomb is free software; you can redistribute it and/or modify
	15	* it under the terms of the GNU Library General Public License as
	16	* published by the Free Software Foundation; either version 2 of the
	17	* License, or (at your option) any later version.
	18	*
	19	* Catacomb is distributed in the hope that it will be useful,
	20	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	21	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	22	* GNU Library General Public License for more details.
	23	*
	24	* You should have received a copy of the GNU Library General Public
	25	* License along with Catacomb; if not, write to the Free
	26	* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
	27	* MA 02111-1307, USA.
	28	*/
	29
34e4f738	30	#ifndef CATACOMB_GROUP_H
	31	#define CATACOMB_GROUP_H
	32
	33	#ifdef __cplusplus
	34	extern "C" {
	35	#endif
	36
	37	/----- Header files ------------------------------------------------------/
	38
	39	#include <mLib/dstr.h>
	40
	41	#ifndef CATACOMB_BUF_H
	42	# include "buf.h"
	43	#endif
	44
	45	#ifndef CATACOMB_DH_H
	46	# include "ec.h"
	47	#endif
	48
	49	#ifndef CATACOMB_GRAND_H
	50	# include "grand.h"
	51	#endif
	52
	53	#ifndef CATACOMB_MP_H
	54	# include "mp.h"
	55	#endif
	56
	57	#ifndef CATACOMB_QDPARSE_H
	58	# include "qdparse.h"
	59	#endif
	60
	61	/----- Data structures ---------------------------------------------------/
	62
	63	#ifndef ge
	64	typedef struct ge ge; /* Group element (abstract type) */
	65	#endif
	66
02d7884d	67	typedef struct group_ {
34e4f738	68	const struct group_ops ops; / Operations table */
34e4f738	69	size_t nbits; /* Size of an element in bits */
0f3faccd	70	size_t noctets; /* Size of raw element in octets */
34e4f738	71	ge i; / Identity element */
	72	ge g; / Generator element */
	73	mp r; / Order of the generator */
	74	mp h; / Cofactor */
	75	} group;
	76
	77	typedef struct group_expfactor {
	78	ge base; / The base */
	79	mp exp; / The exponent */
	80	} group_expfactor;
	81
	82	typedef struct group_ops {
	83	unsigned ty; /* Type of this group */
	84
	85	/* --- Memory management --- */
	86
	87	void (destroygroup)(group /g/);
	88	ge (create)(group /g*/);
	89	void (copy)(group /g/, ge /d/, ge /x/);
	90	void (burn)(group /g/, ge /x*/);
	91	void (destroy)(group /g/, ge /e*/);
	92
	93	/* --- Comparisons --- */
	94
	95	int (samep)(group /g/, group /h*/);
	96	int (eq)(group /g/, ge /x/, ge /y/);
	97	int (identp)(group /g/, ge /x*/);
	98
	99	/* --- Other stuff --- */
	100
	101	const char (check)(group /g/, grand /gr/);
	102
	103	/* --- Arithmetic --- */
	104
	105	void (mul)(group /g/, ge /d/, ge /x/, ge /y*/);
	106	void (sqr)(group /g/, ge /d/, ge /x/);
	107	void (inv)(group /g/, ge /d/, ge /x/);
	108	void (div)(group /g/, ge /d/, ge /x/, ge /y*/);
	109	void (exp)(group /g/, ge /d/, ge /x/, mp /n*/);
	110	void (mexp)(group /g/, ge /d*/,
	111	const group_expfactor /f/, size_t /n*/);
	112
	113	/* --- Debugging --- */
	114
	115	int (read)(group /g/, ge /d*/,
	116	const mptext_ops /ops/, void /p/);
	117	int (write)(group /g/, ge /x*/,
	118	const mptext_ops /ops/, void /p/);
	119
	120	/* --- Conversions --- */
	121
	122	mp (toint)(group /g/, mp /d/, ge /x*/);
	123	int (fromint)(group /g/, ge /d/, mp /x/);
	124	int (toec)(group /g/, ec /d/, ge /x/);
5c3f75ec	125	int (fromec)(group /g/, ge /d/, const ec /p/);
34e4f738	126	int (tobuf)(group /h/, buf /b/, ge /x/);
34e4f738	127	int (frombuf)(group /h/, buf /b/, ge /d/);
0f3faccd	128	int (toraw)(group /h/, buf /b/, ge /x/);
0f3faccd	129	int (fromraw)(group /h/, buf /b/, ge /d/);
34e4f738	130
	131	} group_ops;
	132
	133	enum {
	134	GTY_PRIME, /* Prime field subgroup */
	135	GTY_BINARY, /* Binary feld subgroup */
	136	GTY_EC /* Elliptic curve group */
	137	};
	138
	139	#define G_DESTROYGROUP(g) (g)->ops->destroygroup((g))
	140	#define G_CREATE(g) (g)->ops->create((g))
	141	#define G_COPY(g, d, x) (g)->ops->copy((g), (d), (x))
	142	#define G_BURN(g, x) (g)->ops->burn((g), (x))
	143	#define G_DESTROY(g, x) (g)->ops->destroy((g), (x))
	144
	145	#define G_SAMEP(g, h) (g)->ops->samep((g), (h))
	146	#define G_EQ(g, x, y) (g)->ops->eq((g), (x), (y))
	147	#define G_IDENTP(g, x) (g)->ops->identp((g), (x))
	148
	149	#define G_CHECK(g, gr) (g)->ops->check((g), (gr))
	150
	151	#define G_MUL(g, d, x, y) (g)->ops->mul((g), (d), (x), (y))
	152	#define G_SQR(g, d, x) (g)->ops->sqr((g), (d), (x))
	153	#define G_INV(g, d, x) (g)->ops->inv((g), (d), (x))
	154	#define G_DIV(g, d, x, y) (g)->ops->div((g), (d), (x), (y))
	155	#define G_EXP(g, d, x, n) (g)->ops->exp((g), (d), (x), (n))
	156	#define G_MEXP(g, d, f, n) (g)->ops->mexp((g), (d), (f), (n))
	157
	158	#define G_READ(g, d, o, p) (g)->ops->read((g), (d), (o), (p))
	159	#define G_WRITE(g, x, o, p) (g)->ops->write((g), (x), (o), (p))
	160
	161	#define G_TOINT(g, d, x) (g)->ops->toint((g), (d), (x))
	162	#define G_FROMINT(g, d, x) (g)->ops->fromint((g), (d), (x))
	163	#define G_TOEC(g, d, x) (g)->ops->toec((g), (d), (x))
	164	#define G_FROMEC(g, d, p) (g)->ops->fromec((g), (d), (p))
	165	#define G_TOBUF(g, b, x) (g)->ops->tobuf((g), (b), (x))
	166	#define G_FROMBUF(g, b, d) (g)->ops->frombuf((g), (b), (d))
0f3faccd	167	#define G_TORAW(g, b, x) (g)->ops->toraw((g), (b), (x))
0f3faccd	168	#define G_FROMRAW(g, b, d) (g)->ops->fromraw((g), (b), (d))
34e4f738	169
	170	/----- Handy functions ---------------------------------------------------/
	171
	172	/* --- @group_check@ --- *
	173	*
	174	* Arguments: @group *g@ = an abstract group
	175	* @ge *x@ = a group element
	176	*
	177	* Returns: Zero on success, nonzero for failure.
	178	*
	179	* Use: Checks that @x@ is a valid group element. This may take a
	180	* while, since it checks that %$x^h \ne 1$%.
	181	*/
	182
	183	extern int group_check(group /g/, ge /x/);
	184
	185	/* --- @group_samep@ --- *
	186	*
	187	* Arguments: @group g, h@ = two abstract groups
	188	*
	189	* Returns: Nonzero if the groups are in fact identical (not just
	190	* isomorphic).
	191	*
	192	* Use: Checks to see whether two groups are actually the same. This
	193	* function does the full check: the group operatrion @samep@
	194	* just does the group-specific details.
	195	*/
	196
	197	extern int group_samep(group /g/, group /h/);
	198
	199	/----- Textual I/O on group elements -------------------------------------/
	200
	201	extern int group_readstring(group /g/, ge /d/,
	202	const char /p/, char /end*/);
	203	extern int group_writestring(group /g/, ge /d/,
	204	char /p/, size_t /sz*/);
	205
	206	extern int group_readfile(group /g/, ge /d/, FILE /fp*/);
	207	extern int group_writefile(group /g/, ge /x/, FILE /fp*/);
	208
	209	extern int group_readdstr(group /g/, ge /d/,
	210	dstr /dd/, size_t /off/);
	211	extern int group_writedstr(group /g/, ge /x/, dstr /d*/);
	212
	213	/----- Standard implementations ------------------------------------------/
	214
	215	/* --- @group_stdidentp@ --- *
	216	*
	217	* Arguments: @group *g@ = abstract group
	218	* @ge *x@ = group element
	219	*
	220	* Returns: Nonzero if %$x$% is the group identity.
	221	*/
	222
	223	extern int group_stdidentp(group /g/, ge /x/);
	224
	225	/* --- @group_stdcheck@ --- *
	226	*
	227	* Arguments: @group *g@ = abstract group
	228	* @grand *gr@ = random number source.
	229	*
	230	* Returns: Null on success, or a pointer to an error message.
	231	*/
	232
233	extern const char group_stdcheck(group /g/, grand /gr*/);
234
235	/* --- @group_stdsqr@ --- *
236	*
237	* Arguments: @group *g@ = abstract group
238	* @ge *d@ = destination pointer
239	* @ge *x@ = group element
240	*
241	* Returns: ---
242	*
243	* Use: Computes %$d = x^2$% as %$d = x x$%.
244	*/
245
246	extern void group_stdsqr(group /g/, ge /d/, ge /x*/);
247
248	/* --- @group_stddiv@ --- *
249	*
250	* Arguments: @group *g@ = abstract group
251	* @ge *d@ = destination pointer
252	* @ge *x@ = dividend
253	* @ge *y@ = divisor
254	*
255	* Returns: ---
256	*
257	* Use: Computes %$d = x/y$% as %$d = x y^{-1}$%.
258	*/
259
260	extern void group_stddiv(group /g/, ge /d/, ge /x/, ge /y/);
261
262	/* --- @group_stdexp@ --- *
263	*
264	* Arguments: @group *g@ = abstract group
265	* @ge *d@ = destination pointer
266	* @ge *x@ = base element
267	* @mp *n@ = exponent
268	*
269	* Returns: ---
270	*
271	* Use: Computes %$d = x^n$% efficiently.
272	*/
273
274	extern void group_stdexp(group /g/, ge /d/, ge /x/, mp /n/);
275
276	/* --- @group_stdmexp@ --- *
277	*
278	* Arguments: @group *g@ = abstract group
279	* @ge *d@ = destination pointer
280	* @const group_expfactor *f@ = vector of factors
281	* @size_t n@ = number of factors
282	*
283	* Returns: ---
284	*
285	* Use: Computes %$d = g_0^{x_0} g_1^{x_1} \ldots$% efficiently.
286	*/
287
288	extern void group_stdmexp(group /g/, ge /d/,
289	const group_expfactor /f/, size_t /n*/);
290
291	/* --- @group_stdtoec@ --- *
292	*
293	* Arguments: @group *g@ = abstract group
294	* @ec *d@ = destination point
295	* @ge *x@ = group element
296	*
297	* Returns: @-1@, indicating failure.
298	*
299	* Use: Fails to convert a group element to an elliptic curve point.
300	*/
301
302	extern int group_stdtoec(group /g/, ec /d/, ge /x*/);
303
304	/* --- @group_stdfromec@ --- *
305	*
306	* Arguments: @group *g@ = abstract group
307	* @ge *d@ = destination pointer
5c3f75ec	308	* @const ec *p@ = elliptic curve point
34e4f738	309	*
	310	* Returns: Zero for success, @-1@ on failure.
	311	*
	312	* Use: Converts %$p$% to a group element by converting its %$x$%-
	313	* coordinate.
	314	*/
	315
5c3f75ec	316	extern int group_stdfromec(group /g/, ge /d/, const ec /p*/);
34e4f738	317
	318	/----- Prime field subgroups ---------------------------------------------/
	319
	320	typedef struct gprime_param {
	321	mp p, q; /* Prime numbers %$p$% and %$q$% */
	322	mp g; / Generates order-%$q$% subgroup */
	323	} gprime_param;
	324
	325	/* --- @group_prime@ --- *
	326	*
	327	* Arguments: @const gprime_param *gp@ = group parameters
	328	*
02d7884d	329	* Returns: A pointer to the group, or null.
34e4f738	330	*
	331	* Use: Constructs an abstract group interface for a subgroup of a
	332	* prime field. Group elements are @mp *@ pointers.
	333	*/
	334
	335	group group_prime(const gprime_param /gp/);
	336
	337	/----- Elliptic curve groups ---------------------------------------------/
	338
	339	/* --- @group_ec@ --- *
	340	*
	341	* Arguments: @const ec_info *ei@ = elliptic curve parameters
	342	*
02d7884d	343	* Returns: A pointer to the group, or null.
34e4f738	344	*
	345	* Use: Constructs an abstract group interface for an elliptic curve
	346	* group. Group elements are @ec@ structures. The contents of
	347	* the @ec_info@ structure becomes the property of the @group@
	348	* object; you can (and should) free the structure itself, but
	349	* calling @ec_freeinfo@ on it is not allowed.
	350	*/
	351
	352	group group_ec(const ec_info /ei/);
	353
	354	/----- General group initialization --------------------------------------/
	355
	356	/* --- @group_parse@ --- *
	357	*
	358	* Arguments: @qd_parse *qd@ = quick-and-dirty parser
	359	*
	360	* Returns: Group pointer, or null for failure.
	361	*
	362	* Use: Parses a group description and returns the group. This has
	363	* the form `TYPE { SPEC }' where TYPE is `prime' or `ec', and
	364	* SPEC is the appropriate kind of group specification of the
	365	* given type.
	366	*/
	367
	368	extern group group_parse(qd_parse /qd/);
	369
	370	/* --- @group_fromstring@ --- *
	371	*
	372	* Arguments: @const char *p@ = pointer to string to read
	373	* @group **gg@ = where to put the group pointer
	374	*
	375	* Returns: Null if OK, or an error string.
	376	*
	377	* Use: Parses a group spec from a string, and returns the group.
	378	*/
	379
	380	extern const char group_fromstring(const char /p/, group */gg*/);
	381
	382	/----- That's all, folks -------------------------------------------------/
	383
	384	#ifdef __cplusplus
	385	}
	386	#endif
	387
	388	#endif