[secnet] / f25519.h

/* -*-c-*-
 *
 * Arithmetic modulo 2^255 - 19
 *
 * (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_F25519_H
#define CATACOMB_F25519_H

#ifdef __cplusplus
  extern "C" {
#endif

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

#include "fake-mLib-bits.h"

#ifndef CATACOMB_QFARITH_H
#  include "qfarith.h"
#endif

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

typedef union {
  int32 p26[10];
} f25519;

  typedef int32 f25519_piece;

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

/* --- @f25519_set@ --- *
 *
 * Arguments:	@f25519 *z@ = where to write the result
 *		@int a@ = a small-ish constant
 *
 * Returns:	---
 *
 * Use:		Sets @z@ to equal @a@.
 */

extern void f25519_set(f25519 */*x*/, int /*a*/);

/* --- @f25519_load@ --- *
 *
 * Arguments:	@f25519 *z@ = where to store the result
 *		@const octet xv[32]@ = source to read
 *
 * Returns:	---
 *
 * Use:		Reads an element of %$\gf{2^{255} - 19}$% in external
 *		representation from @xv@ and stores it in @z@.
 *
 *		External representation is little-endian base-256.  Elements
 *		have multiple encodings, which are not produced by correct
 *		software; use of noncanonical encodings is not an error, and
 *		toleration of them is considered a performance feature.
 *
 *		Some specifications, e.g., RFC7748, require the topmost bit
 *		(i.e., bit 7 of @wv[31]@) to be ignored.  Callers
 *		implementing such specifications should clear the bit
 *		explicitly.  (It's much easier for a caller who wants the bit
 *		to be ignored to clear it than for a caller who wants the bit
 *		to be significant to apply the necessary change by hand.)
 */

extern void f25519_load(f25519 */*z*/, const octet /*xv*/[32]);

/* --- @f25519_store@ --- *
 *
 * Arguments:	@octet zv[32]@ = where to write the result
 *		@const f25519 *x@ = the field element to write
 *
 * Returns:	---
 *
 * Use:		Stores a field element in the given octet vector in external
 *		representation.  A canonical encoding is always stored, so,
 *		in particular, the top bit of @xv[31]@ is always left clear.
 */

extern void f25519_store(octet /*zv*/[32], const f25519 */*x*/);

/* --- @f25519_pick2@ --- *
 *
 * Arguments:	@f25519 *z@ = where to put the result (may alias @x@ or @y@)
 *		@const f25519 *x, *y@ = two operands
 *		@uint32 m@ = a mask
 *
 * Returns:	---
 *
 * Use:		If @m@ is zero, set @z = y@; if @m@ is all-bits-set, then set
 *		@z = x@.  If @m@ has some other value, then scramble @z@ in
 *		an unhelpful way.
 */

extern void f25519_pick2(f25519 */*z*/, const f25519 */*x*/,
			 const f25519 */*y*/, uint32 /*m*/);

/* --- @f25519_pickn@ --- *
 *
 * Arguments:	@f25519 *z@ = where to put the result
 *		@const f25519 *v@ = a table of entries
 *		@size_t n@ = the number of entries in @v@
 *		@size_t i@ = an index
 *
 * Returns:	---
 *
 * Use:		If @0 <= i < n < 32@ then set @z = v[i]@.  If @n >= 32@ then
 *		do something unhelpful; otherwise, if @i >= n@ then set @z@
 *		to zero.
 */

extern void f25519_pickn(f25519 */*z*/, const f25519 */*v*/, size_t /*n*/,
			 size_t /*i*/);

/* --- @f25519_condswap@ --- *
 *
 * Arguments:	@f25519 *x, *y@ = two operands
 *		@uint32 m@ = a mask
 *
 * Returns:	---
 *
 * Use:		If @m@ is zero, do nothing; if @m@ is all-bits-set, then
 *		exchange @x@ and @y@.  If @m@ has some other value, then
 *		scramble @x@ and @y@ in an unhelpful way.
 */

extern void f25519_condswap(f25519 */*x*/, f25519 */*y*/, uint32 /*m*/);

/* --- @f25519_add@ --- *
 *
 * Arguments:	@f25519 *z@ = where to put the result (may alias @x@ or @y@)
 *		@const f25519 *x, *y@ = two operands
 *
 * Returns:	---
 *
 * Use:		Set @z@ to the sum %$x + y$%.
 */

extern void f25519_add(f25519 */*z*/,
		       const f25519 */*x*/, const f25519 */*y*/);

/* --- @f25519_sub@ --- *
 *
 * Arguments:	@f25519 *z@ = where to put the result (may alias @x@ or @y@)
 *		@const f25519 *x, *y@ = two operands
 *
 * Returns:	---
 *
 * Use:		Set @z@ to the difference %$x - y$%.
 */

extern void f25519_sub(f25519 */*z*/,
		       const f25519 */*x*/, const f25519 */*y*/);

/* --- @f25519_neg@ --- *
 *
 * Arguments:	@f25519 *z@ = where to put the result (may alias @x@)
 *		@const f25519 *x@ = an operand
 *
 * Returns:	---
 *
 * Use:		Set @z = -x@.
 */

extern void f25519_neg(f25519 */*z*/, const f25519 */*x*/);

/* --- @f25519_condneg@ --- *
 *
 * Arguments:	@f25519 *z@ = where to put the result (may alias @x@)
 *		@const f25519 *x@ = an operand
 *		@uint32 m@ = a mask
 *
 * Returns:	---
 *
 * Use:		If @m@ is zero, set @z = x@; if @m@ is all-bits-set, then set
 *		@z = -x@.  If @m@ has some other value then scramble @z@ in
 *		an unhelpful way.
 */

extern void f25519_condneg(f25519 */*z*/, const f25519 */*x*/, uint32 /*m*/);

/* --- @f25519_mulconst@ --- *
 *
 * Arguments:	@f25519 *z@ = where to put the result (may alias @x@)
 *		@const f25519 *x@ = an operand
 *		@long a@ = a small-ish constant; %$|a| < 2^{20}$%.
 *
 * Returns:	---
 *
 * Use:		Set @z@ to the product %$a x$%.
 */

extern void f25519_mulconst(f25519 */*z*/, const f25519 */*x*/, long /*a*/);

/* --- @f25519_mul@ --- *
 *
 * Arguments:	@f25519 *z@ = where to put the result (may alias @x@ or @y@)
 *		@const f25519 *x, *y@ = two operands
 *
 * Returns:	---
 *
 * Use:		Set @z@ to the product %$x y$%.
 */

extern void f25519_mul(f25519 */*z*/,
		       const f25519 */*x*/, const f25519 */*y*/);

/* --- @f25519_sqr@ --- *
 *
 * Arguments:	@f25519 *z@ = where to put the result (may alias @x@ or @y@)
 *		@const f25519 *x@ = an operand
 *
 * Returns:	---
 *
 * Use:		Set @z@ to the square %$x^2$%.
 */

extern void f25519_sqr(f25519 */*z*/, const f25519 */*x*/);

/* --- @f25519_inv@ --- *
 *
 * Arguments:	@f25519 *z@ = where to put the result (may alias @x@)
 *		@const f25519 *x@ = an operand
 *
 * Returns:	---
 *
 * Use:		Stores in @z@ the multiplicative inverse %$x^{-1}$%.  If
 *		%$x = 0$% then @z@ is set to zero.  This is considered a
 *		feature.
 */

extern void f25519_inv(f25519 */*z*/, const f25519 */*x*/);

/* --- @f25519_quosqrt@ --- *
 *
 * Arguments:	@f25519 *z@ = where to put the result (may alias @x@ or @y@)
 *		@const f25519 *x, *y@ = two operands
 *
 * Returns:	Zero if successful, @-1@ if %$x/y$% is not a square.
 *
 * Use:		Stores in @z@ the one of the square roots %$\pm\sqrt{x/y}$%.
 *		If %$x = y = 0% then the result is zero; if %$y = 0$% but %$x
 *		\ne 0$% then the operation fails.  If you wanted a specific
 *		square root then you'll have to pick it yourself.
 */

extern int f25519_quosqrt(f25519 */*z*/,
			  const f25519 */*x*/, const f25519 */*y*/);

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

#ifdef __cplusplus
  }
#endif

#endif
Commit	Line	Data
8a7654a6 MW	1	/* --c--
	2	*
	3	* Arithmetic modulo 2^255 - 19
	4	*
	5	* (c) 2017 Straylight/Edgeware
	6	*/
	7
	8	/----- Licensing notice --------------------------------------------------
	9	*
	10	* This file is part of secnet.
	11	* See README for full list of copyright holders.
	12	*
	13	* secnet is free software; you can redistribute it and/or modify it
	14	* under the terms of the GNU General Public License as published by
	15	* the Free Software Foundation; either version d of the License, or
	16	* (at your option) any later version.
	17	*
	18	* secnet is distributed in the hope that it will be useful, but
	19	* WITHOUT ANY WARRANTY; without even the implied warranty of
	20	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	21	* General Public License for more details.
	22	*
	23	* You should have received a copy of the GNU General Public License
	24	* version 3 along with secnet; if not, see
	25	* https://www.gnu.org/licenses/gpl.html.
	26	*
	27	* This file was originally part of Catacomb, but has been automatically
	28	* modified for incorporation into secnet: see `import-catacomb-crypto'
	29	* for details.
	30	*
	31	* Catacomb is free software; you can redistribute it and/or modify
	32	* it under the terms of the GNU Library General Public License as
	33	* published by the Free Software Foundation; either version 2 of the
	34	* License, or (at your option) any later version.
	35	*
	36	* Catacomb is distributed in the hope that it will be useful,
	37	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	38	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	39	* GNU Library General Public License for more details.
	40	*
	41	* You should have received a copy of the GNU Library General Public
	42	* License along with Catacomb; if not, write to the Free
	43	* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
	44	* MA 02111-1307, USA.
	45	*/
	46
	47	#ifndef CATACOMB_F25519_H
	48	#define CATACOMB_F25519_H
	49
	50	#ifdef __cplusplus
	51	extern "C" {
	52	#endif
	53
	54	/----- Header files ------------------------------------------------------/
	55
	56	#include "fake-mLib-bits.h"
	57
	58	#ifndef CATACOMB_QFARITH_H
	59	# include "qfarith.h"
	60	#endif
	61
	62	/----- Data structures ---------------------------------------------------/
	63
	64	typedef union {
65	int32 p26[10];
66	} f25519;
67
a1a6042e MW	68	typedef int32 f25519_piece;
a1a6042e MW	69
8a7654a6 MW	70	/----- Functions provided ------------------------------------------------/
	71
	72	/* --- @f25519_set@ --- *
	73	*
	74	* Arguments: @f25519 *z@ = where to write the result
	75	* @int a@ = a small-ish constant
	76	*
	77	* Returns: ---
	78	*
	79	* Use: Sets @z@ to equal @a@.
	80	*/
	81
	82	extern void f25519_set(f25519 /x/, int /a*/);
	83
	84	/* --- @f25519_load@ --- *
	85	*
	86	* Arguments: @f25519 *z@ = where to store the result
	87	* @const octet xv[32]@ = source to read
	88	*
	89	* Returns: ---
	90	*
	91	* Use: Reads an element of %$\gf{2^{255} - 19}$% in external
	92	* representation from @xv@ and stores it in @z@.
	93	*
	94	* External representation is little-endian base-256. Elements
	95	* have multiple encodings, which are not produced by correct
	96	* software; use of noncanonical encodings is not an error, and
	97	* toleration of them is considered a performance feature.
	98	*
	99	* Some specifications, e.g., RFC7748, require the topmost bit
	100	* (i.e., bit 7 of @wv[31]@) to be ignored. Callers
	101	* implementing such specifications should clear the bit
	102	* explicitly. (It's much easier for a caller who wants the bit
	103	* to be ignored to clear it than for a caller who wants the bit
	104	* to be significant to apply the necessary change by hand.)
	105	*/
	106
	107	extern void f25519_load(f25519 /z/, const octet /xv*/[32]);
	108
	109	/* --- @f25519_store@ --- *
	110	*
	111	* Arguments: @octet zv[32]@ = where to write the result
	112	* @const f25519 *x@ = the field element to write
	113	*
	114	* Returns: ---
	115	*
	116	* Use: Stores a field element in the given octet vector in external
	117	* representation. A canonical encoding is always stored, so,
	118	* in particular, the top bit of @xv[31]@ is always left clear.
	119	*/
	120
	121	extern void f25519_store(octet /zv/[32], const f25519 /x*/);
	122
	123	/* --- @f25519_pick2@ --- *
	124	*
	125	* Arguments: @f25519 *z@ = where to put the result (may alias @x@ or @y@)
	126	* @const f25519 x, y@ = two operands
	127	* @uint32 m@ = a mask
	128	*
	129	* Returns: ---
	130	*
	131	* Use: If @m@ is zero, set @z = y@; if @m@ is all-bits-set, then set
	132	* @z = x@. If @m@ has some other value, then scramble @z@ in
	133	* an unhelpful way.
134	*/
135
136	extern void f25519_pick2(f25519 /z/, const f25519 /x/,
137	const f25519 /y/, uint32 /m*/);
138
139	/* --- @f25519_pickn@ --- *
140	*
141	* Arguments: @f25519 *z@ = where to put the result
142	* @const f25519 *v@ = a table of entries
143	* @size_t n@ = the number of entries in @v@
144	* @size_t i@ = an index
145	*
146	* Returns: ---
147	*
148	* Use: If @0 <= i < n < 32@ then set @z = v[i]@. If @n >= 32@ then
149	* do something unhelpful; otherwise, if @i >= n@ then set @z@
150	* to zero.
151	*/
152
153	extern void f25519_pickn(f25519 /z/, const f25519 /v/, size_t /n/,
154	size_t /i/);
155
156	/* --- @f25519_condswap@ --- *
157	*
158	* Arguments: @f25519 x, y@ = two operands
159	* @uint32 m@ = a mask
160	*
161	* Returns: ---
162	*
163	* Use: If @m@ is zero, do nothing; if @m@ is all-bits-set, then
164	* exchange @x@ and @y@. If @m@ has some other value, then
165	* scramble @x@ and @y@ in an unhelpful way.
166	*/
167
168	extern void f25519_condswap(f25519 /x/, f25519 /y/, uint32 /m/);
169
170	/* --- @f25519_add@ --- *
171	*
172	* Arguments: @f25519 *z@ = where to put the result (may alias @x@ or @y@)
173	* @const f25519 x, y@ = two operands
174	*
175	* Returns: ---
176	*
177	* Use: Set @z@ to the sum %$x + y$%.
178	*/
179
180	extern void f25519_add(f25519 /z*/,
181	const f25519 /x/, const f25519 /y/);
182
183	/* --- @f25519_sub@ --- *
184	*
185	* Arguments: @f25519 *z@ = where to put the result (may alias @x@ or @y@)
186	* @const f25519 x, y@ = two operands
187	*
188	* Returns: ---
189	*
190	* Use: Set @z@ to the difference %$x - y$%.
191	*/
192
193	extern void f25519_sub(f25519 /z*/,
194	const f25519 /x/, const f25519 /y/);
195
196	/* --- @f25519_neg@ --- *
197	*
198	* Arguments: @f25519 *z@ = where to put the result (may alias @x@)
199	* @const f25519 *x@ = an operand
200	*
201	* Returns: ---
202	*
203	* Use: Set @z = -x@.
204	*/
205
206	extern void f25519_neg(f25519 /z/, const f25519 /x/);
207
208	/* --- @f25519_condneg@ --- *
209	*
210	* Arguments: @f25519 *z@ = where to put the result (may alias @x@)
211	* @const f25519 *x@ = an operand
212	* @uint32 m@ = a mask
213	*
214	* Returns: ---
215	*
216	* Use: If @m@ is zero, set @z = x@; if @m@ is all-bits-set, then set
217	* @z = -x@. If @m@ has some other value then scramble @z@ in
218	* an unhelpful way.
219	*/
220
221	extern void f25519_condneg(f25519 /z/, const f25519 /x/, uint32 /m/);
222
223	/* --- @f25519_mulconst@ --- *
224	*
225	* Arguments: @f25519 *z@ = where to put the result (may alias @x@)
226	* @const f25519 *x@ = an operand
227	* @long a@ = a small-ish constant; %$\|a\| < 2^{20}$%.
228	*
229	* Returns: ---
230	*
231	* Use: Set @z@ to the product %$a x$%.
232	*/
233
234	extern void f25519_mulconst(f25519 /z/, const f25519 /x/, long /a/);
235
236	/* --- @f25519_mul@ --- *
237	*
238	* Arguments: @f25519 *z@ = where to put the result (may alias @x@ or @y@)
239	* @const f25519 x, y@ = two operands
240	*
241	* Returns: ---
242	*
243	* Use: Set @z@ to the product %$x y$%.
244	*/
245
246	extern void f25519_mul(f25519 /z*/,
247	const f25519 /x/, const f25519 /y/);
248
249	/* --- @f25519_sqr@ --- *
250	*
251	* Arguments: @f25519 *z@ = where to put the result (may alias @x@ or @y@)
252	* @const f25519 *x@ = an operand
253	*
254	* Returns: ---
255	*
256	* Use: Set @z@ to the square %$x^2$%.
257	*/
258
259	extern void f25519_sqr(f25519 /z/, const f25519 /x/);
260
261	/* --- @f25519_inv@ --- *
262	*
263	* Arguments: @f25519 *z@ = where to put the result (may alias @x@)
264	* @const f25519 *x@ = an operand
265	*
266	* Returns: ---
267	*
268	* Use: Stores in @z@ the multiplicative inverse %$x^{-1}$%. If
269	* %$x = 0$% then @z@ is set to zero. This is considered a
270	* feature.
271	*/
272
273	extern void f25519_inv(f25519 /z/, const f25519 /x/);
274
275	/* --- @f25519_quosqrt@ --- *
276	*
277	* Arguments: @f25519 *z@ = where to put the result (may alias @x@ or @y@)
278	* @const f25519 x, y@ = two operands
279	*
280	* Returns: Zero if successful, @-1@ if %$x/y$% is not a square.
281	*
282	* Use: Stores in @z@ the one of the square roots %$\pm\sqrt{x/y}$%.
283	* If %$x = y = 0% then the result is zero; if %$y = 0$% but %$x
284	* \ne 0$% then the operation fails. If you wanted a specific
285	* square root then you'll have to pick it yourself.
286	*/
287
288	extern int f25519_quosqrt(f25519 /z*/,
289	const f25519 /x/, const f25519 /y/);
290
291	/----- That's all, folks -------------------------------------------------/
292
293	#ifdef __cplusplus
294	}
295	#endif
296
297	#endif