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pub/ed25519.c: Rearrange `ptadd' to use fewer registers.
[catacomb] / pub / ed25519.c
CommitLineData
d56fd9d1
MW		 1/* -*-c-*-
2 *
3 * The Ed25519 signature scheme
4 *
5 * (c) 2017 Straylight/Edgeware
6 */
7
8/*----- Licensing notice --------------------------------------------------*
9 *
10 * This file is part of Catacomb.
11 *
12 * Catacomb is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Library General Public License as
14 * published by the Free Software Foundation; either version 2 of the
15 * License, or (at your option) any later version.
16 *
17 * Catacomb is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU Library General Public License for more details.
21 *
22 * You should have received a copy of the GNU Library General Public
23 * License along with Catacomb; if not, write to the Free
24 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
25 * MA 02111-1307, USA.
26 */
27
28/*----- Header files ------------------------------------------------------*/
29
30#include <string.h>
31
32#include "f25519.h"
33#include "ed25519.h"
34#include "scaf.h"
35#include "sha512.h"
36
37/*----- Key fetching ------------------------------------------------------*/
38
39const key_fetchdef ed25519_pubfetch[] = {
40 { "pub", offsetof(ed25519_pub, pub), KENC_BINARY, 0 },
41 { 0, 0, 0, 0 }
42};
43
44static const key_fetchdef priv[] = {
45 { "priv", offsetof(ed25519_priv, priv), KENC_BINARY, 0 },
46 { 0, 0, 0, 0 }
47};
48
49const key_fetchdef ed25519_privfetch[] = {
50 { "pub", offsetof(ed25519_priv, pub), KENC_BINARY, 0 },
51 { "private", 0, KENC_STRUCT, priv },
52 { 0, 0, 0, 0 }
53};
54
55/*----- A number of magic numbers -----------------------------------------*/
56
57#if SCAF_IMPL == 32
58# define PIECEWD 24
59 static const scaf_piece l[] = {
60 0xf5d3ed, 0x631a5c, 0xd65812, 0xa2f79c, 0xdef9de, 0x000014,
61 0x000000, 0x000000, 0x000000, 0x000000, 0x001000
62 };
63 static const scaf_piece mu[] = {
64 0x1b3994, 0x0a2c13, 0x9ce5a3, 0x29a7ed, 0x5d0863, 0x210621,
65 0xffffeb, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0x000fff
66 };
67#endif
68
69#if SCAF_IMPL == 16
70# define PIECEWD 12
71 static const scaf_piece l[] = {
72 0x3ed, 0xf5d, 0xa5c, 0x631, 0x812, 0xd65,
73 0x79c, 0xa2f, 0x9de, 0xdef, 0x014, 0x000,
74 0x000, 0x000, 0x000, 0x000, 0x000, 0x000,
75 0x000, 0x000, 0x000, 0x001
76 };
77 static const scaf_piece mu[] = {
78 0x994, 0x1b3, 0xc13, 0x0a2, 0x5a3, 0x9ce,
79 0x7ed, 0x29a, 0x863, 0x5d0, 0x621, 0x210,
80 0xfeb, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff,
81 0xfff, 0xfff, 0xfff, 0xfff, 0xfff
82 };
83#endif
84
85#define NPIECE SCAF_NPIECE(255, PIECEWD)
86
87#if F25519_IMPL == 26
88# define P p26
9c077904 89 static const f25519_piece bx_pieces[] = {
d56fd9d1
MW		 90 -14297830, -7645148, 16144683, -16471763, 27570974,
91 -2696100, -26142465, 8378389, 20764389, 8758491
92 }, by_pieces[] = {
a81dbb3f
MW		 93 -26843541, -6710886, 13421773, -13421773, 26843546,
94 6710886, -13421773, 13421773, -26843546, -6710886
d56fd9d1 95 }, d_pieces[] = {
a81dbb3f
MW		 96 -10913610, 13857413, -15372611, 6949391, 114729,
97 -8787816, -6275908, -3247719, -18696448, -12055116
d56fd9d1
MW		 98 };
99#endif
100#if F25519_IMPL == 10
101# define P p10
9c077904 102 static const f25519_piece bx_pieces[] = {
d56fd9d1
MW		 103 282, 373, 242, 386, -467, 86, -423, 318, -437,
104 75, 236, -308, 421, 92, 439, -35, 400, 452,
105 82, -40, 160, 441, -51, 437, -365, 134
106 }, by_pieces[] = {
a81dbb3f 107 -405, 410, -410, 410, -410, -102, 205, -205, 205,
d56fd9d1 108 -205, 205, -410, 410, -410, 410, 102, -205, 205,
a81dbb3f 109 -205, 205, -205, 410, -410, 410, -410, -102
d56fd9d1 110 }, d_pieces[] = {
a81dbb3f 111 182, -418, 310, -216, -178, -133, 367, -315, -380,
d56fd9d1 112 -351, -182, -255, 2, 152, -390, -136, -52, -383,
a81dbb3f 113 -412, -398, -12, 448, -469, -196, 55, -184
d56fd9d1
MW		 114 };
115#endif
116
9c077904 117static const f25519_piece bz_pieces[NPIECE] = { 1, 0, /* ... */ };
d56fd9d1
MW		 118#define BX ((const f25519 *)bx_pieces)
119#define BY ((const f25519 *)by_pieces)
120#define BZ ((const f25519 *)bz_pieces)
121#define D ((const f25519 *)d_pieces)
122
123/*----- Point encoding and decoding ---------------------------------------*/
124
125static void ptencode(octet q[32],
126 const f25519 *X, const f25519 *Y, const f25519 *Z)
127{
128 f25519 x, y, t;
129 octet b[32];
130
131 f25519_inv(&t, Z); f25519_mul(&x, X, &t); f25519_mul(&y, Y, &t);
132 f25519_store(q, &y); f25519_store(b, &x); q[31] |= (b[0]&1u) << 7;
133}
134
135static int ptdecode(f25519 *X, f25519 *Y, f25519 *Z, const octet q[32])
136{
137 octet b[32];
accdbbc9 138 unsigned i, a;
d56fd9d1
MW		 139 f25519 t, u;
140 uint32 m;
accdbbc9 141 int rc = 0;
d56fd9d1 142
accdbbc9 143 /* Load the y-coordinate. */
d56fd9d1 144 memcpy(b, q, 32); b[31] &= 0x7fu; f25519_load(Y, b);
accdbbc9
MW		 145
146 /* Check that the coordinate was in range. If we store it, we'll get a
147 * canonical version which we can compare against Q; be careful not to
148 * check the top bit.
149 */
150 f25519_store(b, Y);
151 for (i = a = 0; i < 31; i++) a |= b[i] ^ q[i];
152 a |= (b[31] ^ q[31])&0x7fu;
153 a = ((a - 1) >> 8)&0x01u; /* 0 |-> 1, non-0 |-> 0 */
154 rc |= (int)a - 1;
155
156 /* Decompress the x-coordinate. */
d56fd9d1 157 f25519_sqr(&t, Y); f25519_mul(&u, &t, D); t.P[0] -= 1; u.P[0] += 1;
accdbbc9
MW		 158 rc |= f25519_quosqrt(X, &t, &u);
159 f25519_store(b, X); m = -(uint32)(((q[31] >> 7) ^ b[0])&0x1u);
d56fd9d1 160 f25519_condneg(X, X, m);
accdbbc9
MW		 161
162 /* Set Z. */
d56fd9d1 163 f25519_set(Z, 1);
accdbbc9
MW		 164
165 /* And we're done. */
d56fd9d1
MW		 166 return (rc);
167}
168
169/*----- Edwards curve arithmetic ------------------------------------------*/
170
171static void ptadd(f25519 *X, f25519 *Y, f25519 *Z,
172 const f25519 *X0, const f25519 *Y0, const f25519 *Z0,
173 const f25519 *X1, const f25519 *Y1, const f25519 *Z1)
174{
3709f795 175 f25519 t0, t1, t2, t3;
d56fd9d1
MW		 176
177 /* Bernstein, Birkner, Joye, Lange, and Peters, `Twisted Edwards Curves',
178 * 2008-03-13, https://cr.yp.to/newelliptic/twisted-20080313.pdf shows the
179 * formulae as:
180 *
181 * A = Z1 Z2; B = A^2; C = X1 X2; D = Y1 Y2;
182 * E = d C D; F = B - E; G = B + E;
183 * X3 = A F ((X1 + Y1) (X2 + Y2) - C - D);
184 * Y3 = A G (D - a C); Z3 = F G.
185 *
186 * Note that a = -1, which things easier.
187 */
188
189 f25519_mul(&t0, Z0, Z1); /* t0 = A = Z0 Z1 */
3709f795
MW		 190 f25519_add(&t1, X0, Y0); /* t1 = X0 + Y0 */
191 f25519_add(&t2, X1, Y1); /* t2 = X1 + Y1 */
192 f25519_mul(&t1, &t1, &t2); /* t1 = (X0 + Y0) (X1 + Y1) */
d56fd9d1
MW		 193 f25519_mul(&t2, X0, X1); /* t2 = C = X0 X1 */
194 f25519_mul(&t3, Y0, Y1); /* t3 = D = Y0 Y1 */
3709f795
MW		 195 f25519_add(Y, &t2, &t3); /* Y = C + D = D - a C */
196 f25519_sub(X, &t1, Y); /* X = (X0 + Y0) (X1 + Y1) - C - D */
197 f25519_mul(X, X, &t0); /* X = A ((X0 + Y0) (X1 + Y1) - C - D) */
198 f25519_mul(Y, Y, &t0); /* Y = A (D - a C) */
199 f25519_sqr(&t0, &t0); /* t0 = B = A^2 */
200 f25519_mul(&t1, &t2, &t3); /* t1 = C D */
201 f25519_mul(&t1, &t1, D); /* t1 = E = d C D */
202 f25519_sub(&t2, &t0, &t1); /* t2 = F = B - E */
203 f25519_add(&t1, &t0, &t1); /* t1 = G = B + E */
204 f25519_mul(X, X, &t2); /* X = A F ((X0 + Y0) (X1 + Y1) - C - D) */
205 f25519_mul(Y, Y, &t1); /* Y = A G (D - a C) */
206 f25519_mul(Z, &t1, &t2); /* Z = F G */
d56fd9d1
MW		 207}
208
209static void ptdbl(f25519 *X, f25519 *Y, f25519 *Z,
210 const f25519 *X0, const f25519 *Y0, const f25519 *Z0)
211{
212 f25519 t0, t1, t2;
213
214 /* Bernstein, Birkner, Joye, Lange, and Peters, `Twisted Edwards Curves',
215 * 2008-03-13, https://cr.yp.to/newelliptic/twisted-20080313.pdf shows the
216 * formulae as:
217 *
218 * B = (X1 + Y1)^2; C = X1^2; D = Y1^2; E = a C;
219 * F = E + D; H = Z1^2; J = F - 2 H;
220 * X3 = (B - C - D) J; Y3 = F (E - D); Z3 = F J.
221 *
222 * Note that a = -1, which things easier.
223 */
224
225 f25519_add(&t0, X0, Y0); /* t0 = X0 + Y0 */
226 f25519_sqr(&t0, &t0); /* t0 = B = (X0 + Y0)^2 */
227 f25519_sqr(&t1, X0); /* t1 = C = X0^2 */
228 f25519_sqr(&t2, Y0); /* t2 = D = Y0^2 */
229 f25519_add(Y, &t1, &t2); /* Y = C + D = -(E - D) */
230 f25519_sub(X, &t0, Y); /* X = B - C - D */
231 /* (E = a C = -C) */
232 f25519_sub(&t0, &t2, &t1); /* t0 = F = D - C = E + D */
233 f25519_sqr(&t1, Z0); /* t1 = H = Z0^2 */
234 f25519_mulconst(&t1, &t1, 2); /* t1 = 2 H */
235 f25519_sub(&t1, &t0, &t1); /* t1 = J = F - 2 H */
236 f25519_mul(X, X, &t1); /* X = (B - C - D) J */
237 f25519_mul(Y, Y, &t0); /* Y = -F (E - D) */
238 f25519_neg(Y, Y); /* Y = F (E - D) */
239 f25519_mul(Z, &t0, &t1); /* Z = F J */
240}
241
242static void ptmul(f25519 *X, f25519 *Y, f25519 *Z,
243 const scaf_piece n[NPIECE],
244 const f25519 *X0, const f25519 *Y0, const f25519 *Z0)
245{
246 /* We assume that the window width divides the scalar piece width. */
247#define WINWD 4
248#define WINLIM (1 << WINWD)
249#define WINMASK (WINLIM - 1)
250#define TABSZ (WINLIM/2 + 1)
251
252 f25519 VX[TABSZ], VY[TABSZ], VZ[TABSZ];
253 f25519 TX, TY, TZ, UX, UY, UZ;
254 unsigned i, j, k, w;
255 uint32 m_neg;
256 scaf_piece ni;
257
258 /* Build a table of small multiples. */
259 f25519_set(&VX[0], 0); f25519_set(&VY[0], 1); f25519_set(&VZ[0], 1);
260 VX[1] = *X0; VY[1] = *Y0; VZ[1] = *Z0;
261 ptdbl(&VX[2], &VY[2], &VZ[2], &VX[1], &VY[1], &VZ[1]);
262 for (i = 3; i < TABSZ; i += 2) {
263 ptadd(&VX[i], &VY[i], &VZ[i],
264 &VX[i - 1], &VY[i - 1], &VZ[i - 1], X0, Y0, Z0);
265 ptdbl(&VX[i + 1], &VY[i + 1], &VZ[i + 1],
266 &VX[(i + 1)/2], &VY[(i + 1)/2], &VZ[(i + 1)/2]);
267 }
268
269 /* Now do the multiplication. We lag a window behind the cursor position
270 * because of the scalar recoding we do.
271 */
272 f25519_set(&TX, 0); f25519_set(&TY, 1); f25519_set(&TZ, 1);
273 for (i = NPIECE, w = 0, m_neg = 0; i--; ) {
274 ni = n[i];
275
276 /* Work through each window in the scalar piece. */
277 for (j = 0; j < PIECEWD; j += WINWD) {
278
279 /* Shift along by a window. */
280 for (k = 0; k < WINWD; k++) ptdbl(&TX, &TY, &TZ, &TX, &TY, &TZ);
281
282 /* Peek at the next window of four bits. If the top bit is set we lend
283 * a bit leftwards, into w. It's too late for this to affect the sign
284 * now, but if we negated earlier then the addition would be wrong.
285 */
286 w += (ni >> (PIECEWD - 1))&0x1u;
287 w = ((WINLIM - w)&m_neg) | (w&~m_neg);
288
289 /* Collect the entry from the table, and add or subtract. */
290 f25519_pickn(&UX, VX, TABSZ, w);
291 f25519_pickn(&UY, VY, TABSZ, w);
292 f25519_pickn(&UZ, VZ, TABSZ, w);
293 f25519_condneg(&UX, &UX, m_neg);
294 ptadd(&TX, &TY, &TZ, &TX, &TY, &TZ, &UX, &UY, &UZ);
295
296 /* Move the next window into the delay slot. If its top bit is set,
297 * then negate it and set m_neg.
298 */
299 w = (ni >> (PIECEWD - WINWD))&WINMASK;
300 m_neg = -(uint32)((w >> (WINWD - 1))&0x1u);
301 ni <<= WINWD;
302 }
303 }
304
305 /* Do the final window. Just fix the sign and go. */
306 for (k = 0; k < WINWD; k++) ptdbl(&TX, &TY, &TZ, &TX, &TY, &TZ);
307 w = ((WINLIM - w)&m_neg) | (w&~m_neg);
308 f25519_pickn(&UX, VX, TABSZ, w);
309 f25519_pickn(&UY, VY, TABSZ, w);
310 f25519_pickn(&UZ, VZ, TABSZ, w);
311 f25519_condneg(&UX, &UX, m_neg);
312 ptadd(X, Y, Z, &TX, &TY, &TZ, &UX, &UY, &UZ);
313
314#undef WINWD
315#undef WINLIM
316#undef WINMASK
317#undef TABSZ
318}
319
320static void ptsimmul(f25519 *X, f25519 *Y, f25519 *Z,
321 const scaf_piece n0[NPIECE],
322 const f25519 *X0, const f25519 *Y0, const f25519 *Z0,
323 const scaf_piece n1[NPIECE],
324 const f25519 *X1, const f25519 *Y1, const f25519 *Z1)
325{
326 /* We assume that the window width divides the scalar piece width. */
327#define WINWD 2
328#define WINLIM (1 << WINWD)
329#define WINMASK (WINLIM - 1)
330#define TABSZ (1 << 2*WINWD)
331
332 f25519 VX[TABSZ], VY[TABSZ], VZ[TABSZ];
333 f25519 TX, TY, TZ, UX, UY, UZ;
334 unsigned i, j, k, w, ni0, ni1;
335
336 /* Build a table of small linear combinations. */
337 f25519_set(&VX[0], 0); f25519_set(&VY[0], 1); f25519_set(&VZ[0], 1);
338 VX[1] = *X0; VX[WINLIM] = *X1;
339 VY[1] = *Y0; VY[WINLIM] = *Y1;
340 VZ[1] = *Z0; VZ[WINLIM] = *Z1;
341 for (i = 2; i < WINLIM; i <<= 1) {
342 ptdbl(&VX[i], &VY[i], &VZ[i],
343 &VX[i/2], &VY[i/2], &VZ[i/2]);
344 ptdbl(&VX[i*WINLIM], &VY[i*WINLIM], &VZ[i*WINLIM],
345 &VX[i*WINLIM/2], &VY[i*WINLIM/2], &VZ[i*WINLIM/2]);
346 }
347 for (i = 2; i < TABSZ; i <<= 1) {
348 for (j = 1; j < i; j++)
349 ptadd(&VX[i + j], &VY[i + j], &VZ[i + j],
350 &VX[i], &VY[i], &VZ[i], &VX[j], &VY[j], &VZ[j]);
351 }
352
353 /* Do the multiplication. */
354 f25519_set(&TX, 0); f25519_set(&TY, 1); f25519_set(&TZ, 1);
355 for (i = NPIECE; i--; ) {
356 ni0 = n0[i]; ni1 = n1[i];
357
358 /* Work through each window in the scalar pieces. */
359 for (j = 0; j < PIECEWD; j += WINWD) {
360
361 /* Shift along by a window. */
362 for (k = 0; k < WINWD; k++) ptdbl(&TX, &TY, &TZ, &TX, &TY, &TZ);
363
364 /* Collect the next window from the scalars. */
365 w = ((ni0 >> (PIECEWD - WINWD))&WINMASK) |
366 ((ni1 >> (PIECEWD - 2*WINWD))&(WINMASK << WINWD));
367 ni0 <<= WINWD; ni1 <<= WINWD;
368
369 /* Collect the entry from the table, and add. */
370 f25519_pickn(&UX, VX, TABSZ, w);
371 f25519_pickn(&UY, VY, TABSZ, w);
372 f25519_pickn(&UZ, VZ, TABSZ, w);
373 ptadd(&TX, &TY, &TZ, &TX, &TY, &TZ, &UX, &UY, &UZ);
374 }
375 }
376
377 /* Done. */
378 *X = TX; *Y = TY; *Z = TZ;
379}
380
381/*----- Key derivation utilities ------------------------------------------*/
382
383static void unpack_key(scaf_piece a[NPIECE], octet h1[32],
384 const octet *k, size_t ksz)
385{
386 sha512_ctx h;
387 octet b[SHA512_HASHSZ];
388
389 sha512_init(&h); sha512_hash(&h, k, ksz); sha512_done(&h, b);
390 b[0] &= 0xf8u; b[31] = (b[31]&0x3f) | 0x40;
391 scaf_load(a, b, 32, NPIECE, PIECEWD);
cb2f9158 392 if (h1) memcpy(h1, b + 32, 32);
d56fd9d1
MW		 393}
394
395/*----- Main code ---------------------------------------------------------*/
396
397/* --- @ed25519_pubkey@ --- *
398 *
399 * Arguments: @octet K[ED25519_PUBSZ]@ = where to put the public key
400 * @const void *k@ = private key
401 * @size_t ksz@ = length of private key
402 *
403 * Returns: ---
404 *
405 * Use: Derives the public key from a private key.
406 */
407
408void ed25519_pubkey(octet K[ED25519_PUBSZ], const void *k, size_t ksz)
409{
410 scaf_piece a[NPIECE];
411 f25519 AX, AY, AZ;
d56fd9d1 412
cb2f9158 413 unpack_key(a, 0, k, ksz);
d56fd9d1
MW		 414 ptmul(&AX, &AY, &AZ, a, BX, BY, BZ);
415 ptencode(K, &AX, &AY, &AZ);
416}
417
418/* --- @ed25519_sign@ --- *
419 *
420 * Arguments: @octet sig[ED25519_SIGSZ]@ = where to put the signature
421 * @const void *k@ = private key
422 * @size_t ksz@ = length of private key
423 * @const octet K[ED25519_PUBSZ]@ = public key
424 * @const void *m@ = message to sign
425 * @size_t msz@ = length of message
426 *
427 * Returns: ---
428 *
429 * Use: Signs a message.
430 */
431
432void ed25519_sign(octet sig[ED25519_SIGSZ],
433 const void *k, size_t ksz,
434 const octet K[ED25519_PUBSZ],
435 const void *m, size_t msz)
436{
437 sha512_ctx h;
438 scaf_piece a[NPIECE], r[NPIECE], t[NPIECE], scratch[3*NPIECE + 1];
439 scaf_dblpiece tt[2*NPIECE];
440 f25519 RX, RY, RZ;
441 octet h1[32], b[SHA512_HASHSZ];
442 unsigned i;
443
444 /* Get my private key. */
445 unpack_key(a, h1, k, ksz);
446
447 /* Select the nonce and the vector part. */
448 sha512_init(&h);
449 sha512_hash(&h, h1, 32);
450 sha512_hash(&h, m, msz);
451 sha512_done(&h, b);
452 scaf_loaddbl(tt, b, 64, 2*NPIECE, PIECEWD);
453 scaf_reduce(r, tt, l, mu, NPIECE, PIECEWD, scratch);
454 ptmul(&RX, &RY, &RZ, r, BX, BY, BZ);
455 ptencode(sig, &RX, &RY, &RZ);
456
457 /* Calculate the scalar part. */
458 sha512_init(&h);
459 sha512_hash(&h, sig, 32);
460 sha512_hash(&h, K, 32);
461 sha512_hash(&h, m, msz);
462 sha512_done(&h, b);
463 scaf_loaddbl(tt, b, 64, 2*NPIECE, PIECEWD);
464 scaf_reduce(t, tt, l, mu, NPIECE, PIECEWD, scratch);
465 scaf_mul(tt, t, a, NPIECE);
466 for (i = 0; i < NPIECE; i++) tt[i] += r[i];
467 scaf_reduce(t, tt, l, mu, NPIECE, PIECEWD, scratch);
468 scaf_store(sig + 32, 32, t, NPIECE, PIECEWD);
469}
470
471/* --- @ed25519_verify@ --- *
472 *
473 * Arguments: @const octet K[ED25519_PUBSZ]@ = public key
474 * @const void *m@ = message to sign
475 * @size_t msz@ = length of message
476 * @const octet sig[ED25519_SIGSZ]@ = signature
477 *
478 * Returns: Zero if OK, negative on failure.
479 *
480 * Use: Verify a signature.
481 */
482
483int ed25519_verify(const octet K[ED25519_PUBSZ],
484 const void *m, size_t msz,
485 const octet sig[ED25519_SIGSZ])
486{
487 sha512_ctx h;
488 scaf_piece s[NPIECE], t[NPIECE], scratch[3*NPIECE + 1];
489 scaf_dblpiece tt[2*NPIECE];
490 f25519 AX, AY, AZ, RX, RY, RZ;
491 octet b[SHA512_HASHSZ];
492
493 /* Unpack the public key. Negate it: we're meant to subtract the term
494 * involving the public key point, and this is easier than negating the
495 * scalar.
496 */
497 if (ptdecode(&AX, &AY, &AZ, K)) return (-1);
498 f25519_neg(&AX, &AX);
499
accdbbc9
MW		 500 /* Load the scalar and check that it's in range. The easy way is to store
501 * it again and see if the two match.
502 */
503 scaf_loaddbl(tt, sig + 32, 32, 2*NPIECE, PIECEWD);
504 scaf_reduce(s, tt, l, mu, NPIECE, PIECEWD, scratch);
505 scaf_store(b, 32, s, NPIECE, PIECEWD);
506 if (memcmp(b, sig + 32, 32) != 0) return (-1);
507
d56fd9d1
MW		 508 /* Check the signature. */
509 sha512_init(&h);
510 sha512_hash(&h, sig, 32);
511 sha512_hash(&h, K, 32);
512 sha512_hash(&h, m, msz);
513 sha512_done(&h, b);
d56fd9d1
MW		 514 scaf_loaddbl(tt, b, 64, 2*NPIECE, PIECEWD);
515 scaf_reduce(t, tt, l, mu, NPIECE, PIECEWD, scratch);
516 ptsimmul(&RX, &RY, &RZ, s, BX, BY, BZ, t, &AX, &AY, &AZ);
517 ptencode(b, &RX, &RY, &RZ);
518 if (memcmp(b, sig, 32) != 0) return (-1);
519
520 /* All is good. */
521 return (0);
522}
523
524/*----- Test rig ----------------------------------------------------------*/
525
526#ifdef TEST_RIG
527
528#include <stdio.h>
529#include <string.h>
530
531#include <mLib/report.h>
532#include <mLib/testrig.h>
533
534static int vrf_pubkey(dstr dv[])
535{
536 dstr dpub = DSTR_INIT;
537 int ok = 1;
538
1b59808c 539 if (dv[1].len != ED25519_PUBSZ) die(1, "bad pub length");
d56fd9d1 540
1b59808c 541 dstr_ensure(&dpub, ED25519_PUBSZ); dpub.len = ED25519_PUBSZ;
d56fd9d1 542 ed25519_pubkey((octet *)dpub.buf, dv[0].buf, dv[0].len);
1b59808c 543 if (memcmp(dpub.buf, dv[1].buf, ED25519_PUBSZ) != 0) {
d56fd9d1
MW		 544 ok = 0;
545 fprintf(stderr, "failed!");
546 fprintf(stderr, "\n\tpriv = "); type_hex.dump(&dv[0], stderr);
547 fprintf(stderr, "\n\tcalc = "); type_hex.dump(&dpub, stderr);
548 fprintf(stderr, "\n\twant = "); type_hex.dump(&dv[1], stderr);
549 fprintf(stderr, "\n");
550 }
551
552 dstr_destroy(&dpub);
553 return (ok);
554}
555
556static int vrf_sign(dstr dv[])
557{
558 octet K[ED25519_PUBSZ];
559 dstr dsig = DSTR_INIT;
560 int ok = 1;
561
1b59808c 562 if (dv[2].len != ED25519_SIGSZ) die(1, "bad result length");
d56fd9d1 563
1b59808c 564 dstr_ensure(&dsig, ED25519_SIGSZ); dsig.len = ED25519_SIGSZ;
d56fd9d1
MW		 565 ed25519_pubkey(K, dv[0].buf, dv[0].len);
566 ed25519_sign((octet *)dsig.buf, dv[0].buf, dv[0].len, K,
567 dv[1].buf, dv[1].len);
1b59808c 568 if (memcmp(dsig.buf, dv[2].buf, ED25519_SIGSZ) != 0) {
d56fd9d1
MW		 569 ok = 0;
570 fprintf(stderr, "failed!");
571 fprintf(stderr, "\n\tpriv = "); type_hex.dump(&dv[0], stderr);
572 fprintf(stderr, "\n\t msg = "); type_hex.dump(&dv[1], stderr);
573 fprintf(stderr, "\n\tcalc = "); type_hex.dump(&dsig, stderr);
574 fprintf(stderr, "\n\twant = "); type_hex.dump(&dv[2], stderr);
575 fprintf(stderr, "\n");
576 }
577
578 dstr_destroy(&dsig);
579 return (ok);
580}
581
582static int vrf_verify(dstr dv[])
583{
584 int rc_want, rc_calc;
585 int ok = 1;
586
1b59808c
MW		 587 if (dv[0].len != ED25519_PUBSZ) die(1, "bad pub length");
588 if (dv[2].len != ED25519_SIGSZ) die(1, "bad sig length");
d56fd9d1
MW		 589 rc_want = *(int *)dv[3].buf;
590
591 rc_calc = ed25519_verify((const octet *)dv[0].buf,
592 dv[1].buf, dv[1].len,
593 (const octet *)dv[2].buf);
594 if (!rc_want != !rc_calc) {
595 ok = 0;
596 fprintf(stderr, "failed!");
597 fprintf(stderr, "\n\t pub = "); type_hex.dump(&dv[0], stderr);
598 fprintf(stderr, "\n\t msg = "); type_hex.dump(&dv[1], stderr);
599 fprintf(stderr, "\n\t sig = "); type_hex.dump(&dv[2], stderr);
600 fprintf(stderr, "\n\tcalc = %d", rc_calc);
601 fprintf(stderr, "\n\twant = %d", rc_want);
602 fprintf(stderr, "\n");
603 }
604
605 return (ok);
606}
607
608static test_chunk tests[] = {
609 { "pubkey", vrf_pubkey, { &type_hex, &type_hex } },
610 { "sign", vrf_sign, { &type_hex, &type_hex, &type_hex } },
611 { "verify", vrf_verify, { &type_hex, &type_hex, &type_hex, &type_int } },
612 { 0, 0, { 0 } }
613};
614
615int main(int argc, char *argv[])
616{
617 test_run(argc, argv, tests, SRCDIR "/t/ed25519");
618 return (0);
619}
620
621#endif
622
623/*----- That's all, folks -------------------------------------------------*/
Catacomb cryptographic library