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8a7654a6 MW |
1 | /* -*-c-*- |
2 | * | |
3 | * Arithmetic in the Goldilocks field GF(2^448 - 2^224 - 1) | |
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_FGOLDI_H | |
48 | #define CATACOMB_FGOLDI_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 p28[16]; | |
66 | } fgoldi; | |
67 | ||
a1a6042e MW |
68 | typedef int32 fgoldi_piece; |
69 | ||
8a7654a6 MW |
70 | /*----- Functions provided ------------------------------------------------*/ |
71 | ||
72 | /* --- @fgoldi_load@ --- * | |
73 | * | |
74 | * Arguments: @fgoldi *z@ = where to store the result | |
75 | * @const octet xv[56]@ = source to read | |
76 | * | |
77 | * Returns: --- | |
78 | * | |
79 | * Use: Reads an element of %$\gf{2^{448} - 2^{224} - 19}$% in | |
80 | * external representation from @xv@ and stores it in @z@. | |
81 | * | |
82 | * External representation is little-endian base-256. Some | |
83 | * elements have multiple encodings, which are not produced by | |
84 | * correct software; use of noncanonical encodings is not an | |
85 | * error, and toleration of them is considered a performance | |
86 | * feature. | |
87 | */ | |
88 | ||
89 | extern void fgoldi_load(fgoldi */*z*/, const octet /*xv*/[56]); | |
90 | ||
91 | /* --- @fgoldi_store@ --- * | |
92 | * | |
93 | * Arguments: @octet zv[56]@ = where to write the result | |
94 | * @const fgoldi *x@ = the field element to write | |
95 | * | |
96 | * Returns: --- | |
97 | * | |
98 | * Use: Stores a field element in the given octet vector in external | |
99 | * representation. A canonical encoding is always stored. | |
100 | */ | |
101 | ||
102 | extern void fgoldi_store(octet /*zv*/[56], const fgoldi */*x*/); | |
103 | ||
104 | /* --- @fgoldi_set@ --- * | |
105 | * | |
106 | * Arguments: @fgoldi *z@ = where to write the result | |
107 | * @int a@ = a small-ish constant | |
108 | * | |
109 | * Returns: --- | |
110 | * | |
111 | * Use: Sets @z@ to equal @a@. | |
112 | */ | |
113 | ||
114 | extern void fgoldi_set(fgoldi */*x*/, int /*a*/); | |
115 | ||
116 | /* --- @fgoldi_add@ --- * | |
117 | * | |
118 | * Arguments: @fgoldi *z@ = where to put the result (may alias @x@ or @y@) | |
119 | * @const fgoldi *x, *y@ = two operands | |
120 | * | |
121 | * Returns: --- | |
122 | * | |
123 | * Use: Set @z@ to the sum %$x + y$%. | |
124 | */ | |
125 | ||
126 | extern void fgoldi_add(fgoldi */*z*/, | |
127 | const fgoldi */*x*/, const fgoldi */*y*/); | |
128 | ||
129 | /* --- @fgoldi_sub@ --- * | |
130 | * | |
131 | * Arguments: @fgoldi *z@ = where to put the result (may alias @x@ or @y@) | |
132 | * @const fgoldi *x, *y@ = two operands | |
133 | * | |
134 | * Returns: --- | |
135 | * | |
136 | * Use: Set @z@ to the difference %$x - y$%. | |
137 | */ | |
138 | ||
139 | extern void fgoldi_sub(fgoldi */*z*/, | |
140 | const fgoldi */*x*/, const fgoldi */*y*/); | |
141 | ||
a1a6042e MW |
142 | /* --- @fgoldi_neg@ --- * |
143 | * | |
144 | * Arguments: @fgoldi *z@ = where to put the result (may alias @x@) | |
145 | * @const fgoldi *x@ = an operand | |
146 | * | |
147 | * Returns: --- | |
148 | * | |
149 | * Use: Set @z = -x@. | |
150 | */ | |
151 | ||
152 | extern void fgoldi_neg(fgoldi */*z*/, const fgoldi */*x*/); | |
153 | ||
154 | /* --- @fgoldi_pick2@ --- * | |
155 | * | |
156 | * Arguments: @fgoldi *z@ = where to put the result (may alias @x@ or @y@) | |
157 | * @const fgoldi *x, *y@ = two operands | |
158 | * @uint32 m@ = a mask | |
159 | * | |
160 | * Returns: --- | |
161 | * | |
162 | * Use: If @m@ is zero, set @z = y@; if @m@ is all-bits-set, then set | |
163 | * @z = x@. If @m@ has some other value, then scramble @z@ in | |
164 | * an unhelpful way. | |
165 | */ | |
166 | ||
167 | extern void fgoldi_pick2(fgoldi */*z*/, | |
168 | const fgoldi */*x*/, const fgoldi */*y*/, | |
169 | uint32 /*m*/); | |
170 | ||
171 | /* --- @fgoldi_pickn@ --- * | |
172 | * | |
173 | * Arguments: @fgoldi *z@ = where to put the result | |
174 | * @const fgoldi *v@ = a table of entries | |
175 | * @size_t n@ = the number of entries in @v@ | |
176 | * @size_t i@ = an index | |
177 | * | |
178 | * Returns: --- | |
179 | * | |
180 | * Use: If @0 <= i < n < 32@ then set @z = v[i]@. If @n >= 32@ then | |
181 | * do something unhelpful; otherwise, if @i >= n@ then set @z@ | |
182 | * to zero. | |
183 | */ | |
184 | ||
185 | extern void fgoldi_pickn(fgoldi */*z*/, | |
186 | const fgoldi */*v*/, size_t /*n*/, size_t /*i*/); | |
187 | ||
8a7654a6 MW |
188 | /* --- @fgoldi_condswap@ --- * |
189 | * | |
190 | * Arguments: @fgoldi *x, *y@ = two operands | |
191 | * @uint32 m@ = a mask | |
192 | * | |
193 | * Returns: --- | |
194 | * | |
195 | * Use: If @m@ is zero, do nothing; if @m@ is all-bits-set, then | |
196 | * exchange @x@ and @y@. If @m@ has some other value, then | |
197 | * scramble @x@ and @y@ in an unhelpful way. | |
198 | */ | |
199 | ||
200 | extern void fgoldi_condswap(fgoldi */*x*/, fgoldi */*y*/, uint32 /*m*/); | |
201 | ||
a1a6042e MW |
202 | /* --- @fgoldi_condneg@ --- * |
203 | * | |
204 | * Arguments: @fgoldi *z@ = where to put the result (may alias @x@) | |
205 | * @const fgoldi *x@ = an operand | |
206 | * @uint32 m@ = a mask | |
207 | * | |
208 | * Returns: --- | |
209 | * | |
210 | * Use: If @m@ is zero, set @z = x@; if @m@ is all-bits-set, then set | |
211 | * @z = -x@. If @m@ has some other value then scramble @z@ in | |
212 | * an unhelpful way. | |
213 | */ | |
214 | ||
215 | extern void fgoldi_condneg(fgoldi */*z*/, const fgoldi */*x*/, uint32 /*m*/); | |
216 | ||
8a7654a6 MW |
217 | /* --- @fgoldi_mulconst@ --- * |
218 | * | |
219 | * Arguments: @fgoldi *z@ = where to put the result (may alias @x@) | |
220 | * @const fgoldi *x@ = an operand | |
221 | * @long a@ = a small-ish constant; %$|a| < 2^{20}$%. | |
222 | * | |
223 | * Returns: --- | |
224 | * | |
225 | * Use: Set @z@ to the product %$a x$%. | |
226 | */ | |
227 | ||
228 | extern void fgoldi_mulconst(fgoldi */*z*/, const fgoldi */*x*/, long /*a*/); | |
229 | ||
230 | /* --- @fgoldi_mul@ --- * | |
231 | * | |
232 | * Arguments: @fgoldi *z@ = where to put the result (may alias @x@ or @y@) | |
233 | * @const fgoldi *x, *y@ = two operands | |
234 | * | |
235 | * Returns: --- | |
236 | * | |
237 | * Use: Set @z@ to the product %$x y$%. | |
238 | */ | |
239 | ||
240 | extern void fgoldi_mul(fgoldi */*z*/, | |
241 | const fgoldi */*x*/, const fgoldi */*y*/); | |
242 | ||
243 | /* --- @fgoldi_sqr@ --- * | |
244 | * | |
245 | * Arguments: @fgoldi *z@ = where to put the result (may alias @x@ or @y@) | |
246 | * @const fgoldi *x@ = an operand | |
247 | * | |
248 | * Returns: --- | |
249 | * | |
250 | * Use: Set @z@ to the square %$x^2$%. | |
251 | */ | |
252 | ||
253 | extern void fgoldi_sqr(fgoldi */*z*/, const fgoldi */*x*/); | |
254 | ||
255 | /* --- @fgoldi_inv@ --- * | |
256 | * | |
257 | * Arguments: @fgoldi *z@ = where to put the result (may alias @x@) | |
258 | * @const fgoldi *x@ = an operand | |
259 | * | |
260 | * Returns: --- | |
261 | * | |
262 | * Use: Stores in @z@ the multiplicative inverse %$x^{-1}$%. If | |
263 | * %$x = 0$% then @z@ is set to zero. This is considered a | |
264 | * feature. | |
265 | */ | |
266 | ||
267 | extern void fgoldi_inv(fgoldi */*z*/, const fgoldi */*x*/); | |
268 | ||
a1a6042e MW |
269 | /* --- @fgoldi_quosqrt@ --- * |
270 | * | |
271 | * Arguments: @fgoldi *z@ = where to put the result (may alias @x@ or @y@) | |
272 | * @const fgoldi *x, *y@ = two operands | |
273 | * | |
274 | * Returns: Zero if successful, @-1@ if %$x/y$% is not a square. | |
275 | * | |
276 | * Use: Stores in @z@ the one of the square roots %$\pm\sqrt{x/y}$%. | |
277 | * If %$x = y = 0% then the result is zero; if %$y = 0$% but %$x | |
278 | * \ne 0$% then the operation fails. If you wanted a specific | |
279 | * square root then you'll have to pick it yourself. | |
280 | */ | |
281 | ||
282 | extern int fgoldi_quosqrt(fgoldi */*z*/, | |
283 | const fgoldi */*x*/, const fgoldi */*y*/); | |
284 | ||
8a7654a6 MW |
285 | /*----- That's all, folks -------------------------------------------------*/ |
286 | ||
287 | #ifdef __cplusplus | |
288 | } | |
289 | #endif | |
290 | ||
291 | #endif |