mdw@git.distorted.org.uk Git - catacomb/blob - pub/ed25519.c

   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
  39 const key_fetchdef ed25519_pubfetch[] = {
  40   { "pub",      offsetof(ed25519_pub, pub),     KENC_BINARY,    0 },
  41   { 0,          0,                              0,              0 }
  42 };
  43
  44 static const key_fetchdef priv[] = {
  45   { "priv",     offsetof(ed25519_priv, priv),   KENC_BINARY,    0 },
  46   { 0,          0,                              0,              0 }
  47 };
  48
  49 const 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
  89   static const int32 bx_pieces[] = {
  90     -14297830,  -7645148,  16144683, -16471763,  27570974,
  91      -2696100, -26142465,   8378389,  20764389,   8758491
  92   }, by_pieces[] = {
  93     -26843560,  -6710886,  13421773, -13421773,  26843546,
  94       6710886, -13421773,  13421773, -26843546,  26843546
  95   }, d_pieces[] = {
  96     -10913629,  13857413, -15372611,   6949391,    114729,
  97      -8787816,  -6275908,  -3247719, -18696448,  21499316
  98   };
  99 #endif
 100 #if F25519_IMPL == 10
 101 # define P p10
 102   static const int16 bx_pieces[] = {
 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[] = {
 107     -424,  410, -410,  410, -410, -102,  205, -205,  205,
 108     -205,  205, -410,  410, -410,  410,  102, -205,  205,
 109     -205,  205, -205,  410, -410,  410, -410,  410
 110   }, d_pieces[] = {
 111      163, -418,  310, -216, -178, -133,  367, -315, -380,
 112     -351, -182, -255,    2,  152, -390, -136,  -52, -383,
 113     -412, -398,  -12,  448, -469, -196,   55,  328
 114   };
 115 #endif
 116
 117 static const scaf_piece bz_pieces[NPIECE] = { 1, 0, /* ... */ };
 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
 125 static 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
 135 static int ptdecode(f25519 *X, f25519 *Y, f25519 *Z, const octet q[32])
 136 {
 137   octet b[32];
 138   f25519 t, u;
 139   uint32 m;
 140   int rc;
 141
 142   memcpy(b, q, 32); b[31] &= 0x7fu; f25519_load(Y, b);
 143   f25519_sqr(&t, Y); f25519_mul(&u, &t, D); t.P[0] -= 1; u.P[0] += 1;
 144   rc = f25519_quosqrt(X, &t, &u);
 145   f25519_store(b, X); m = -(((q[31] >> 7) ^ b[0])&0x1u);
 146   f25519_condneg(X, X, m);
 147   f25519_set(Z, 1);
 148   return (rc);
 149 }
 150
 151 /*----- Edwards curve arithmetic ------------------------------------------*/
 152
 153 static void ptadd(f25519 *X, f25519 *Y, f25519 *Z,
 154                   const f25519 *X0, const f25519 *Y0, const f25519 *Z0,
 155                   const f25519 *X1, const f25519 *Y1, const f25519 *Z1)
 156 {
 157   f25519 t0, t1, t2, t3, t4, t5;
 158
 159   /* Bernstein, Birkner, Joye, Lange, and Peters, `Twisted Edwards Curves',
 160    * 2008-03-13, https://cr.yp.to/newelliptic/twisted-20080313.pdf shows the
 161    * formulae as:
 162    *
 163    *    A = Z1 Z2;   B = A^2;   C = X1 X2;   D = Y1 Y2;
 164    *    E = d C D;   F = B - E;   G = B + E;
 165    *    X3 = A F ((X1 + Y1) (X2 + Y2) - C - D);
 166    *    Y3 = A G (D - a C);   Z3 = F G.
 167    *
 168    * Note that a = -1, which things easier.
 169    */
 170
 171   f25519_mul(&t0, Z0, Z1);              /* t0 = A = Z0 Z1 */
 172   f25519_sqr(&t1, &t0);                 /* t1 = B = A^2 */
 173   f25519_mul(&t2, X0, X1);              /* t2 = C = X0 X1 */
 174   f25519_mul(&t3, Y0, Y1);              /* t3 = D = Y0 Y1 */
 175   f25519_mul(&t4, &t2, &t3);            /* t4 = C D */
 176   f25519_mul(&t4, &t4, D);              /* t4 = E = d C D */
 177   f25519_sub(&t5, &t1, &t4);            /* t5 = F = B - E */
 178   f25519_add(&t4, &t1, &t4);            /* t4 = G = B + E */
 179   f25519_add(&t1, &t2, &t3);            /* t1 = C + D */
 180   f25519_add(&t2, X0, Y0);              /* t2 = X0 + Y0 */
 181   f25519_add(&t3, X1, Y1);              /* t3 = X1 + Y1 */
 182   f25519_mul(X, &t0, &t5);              /* X = A F */
 183   f25519_mul(Y, &t0, &t4);              /* Y = A G */
 184   f25519_mul(Z, &t5, &t4);              /* Z = F G */
 185   f25519_mul(Y, Y, &t1);                /* Y = A G (C + D) = A G (D - a C) */
 186   f25519_mul(&t0, &t2, &t3);            /* t0 = (X0 + Y0) (X1 + Y1) */
 187   f25519_sub(&t0, &t0, &t1);           /* t0 = (X0 + Y0) (X1 + Y1) - C - D */
 188   f25519_mul(X, X, &t0);          /* X = A F ((X0 + Y0) (X1 + Y1) - C - D) */
 189 }
 190
 191 static void ptdbl(f25519 *X, f25519 *Y, f25519 *Z,
 192                   const f25519 *X0, const f25519 *Y0, const f25519 *Z0)
 193 {
 194   f25519 t0, t1, t2;
 195
 196   /* Bernstein, Birkner, Joye, Lange, and Peters, `Twisted Edwards Curves',
 197    * 2008-03-13, https://cr.yp.to/newelliptic/twisted-20080313.pdf shows the
 198    * formulae as:
 199    *
 200    *    B = (X1 + Y1)^2;   C = X1^2;   D = Y1^2;   E = a C;
 201    *    F = E + D;   H = Z1^2;   J = F - 2 H;
 202    *    X3 = (B - C - D) J;   Y3 = F (E - D);   Z3 = F J.
 203    *
 204    * Note that a = -1, which things easier.
 205    */
 206
 207   f25519_add(&t0, X0, Y0);              /* t0 = X0 + Y0 */
 208   f25519_sqr(&t0, &t0);                 /* t0 = B = (X0 + Y0)^2 */
 209   f25519_sqr(&t1, X0);                  /* t1 = C = X0^2 */
 210   f25519_sqr(&t2, Y0);                  /* t2 = D = Y0^2 */
 211   f25519_add(Y, &t1, &t2);              /* Y = C + D = -(E - D) */
 212   f25519_sub(X, &t0, Y);                /* X = B - C - D */
 213                                         /* (E = a C = -C) */
 214   f25519_sub(&t0, &t2, &t1);            /* t0 = F = D - C = E + D */
 215   f25519_sqr(&t1, Z0);                  /* t1 = H = Z0^2 */
 216   f25519_mulconst(&t1, &t1, 2);         /* t1 = 2 H */
 217   f25519_sub(&t1, &t0, &t1);            /* t1 = J = F - 2 H */
 218   f25519_mul(X, X, &t1);                /* X = (B - C - D) J */
 219   f25519_mul(Y, Y, &t0);                /* Y = -F (E - D) */
 220   f25519_neg(Y, Y);                     /* Y = F (E - D) */
 221   f25519_mul(Z, &t0, &t1);              /* Z = F J */
 222 }
 223
 224 static void ptmul(f25519 *X, f25519 *Y, f25519 *Z,
 225                   const scaf_piece n[NPIECE],
 226                   const f25519 *X0, const f25519 *Y0, const f25519 *Z0)
 227 {
 228   /* We assume that the window width divides the scalar piece width. */
 229 #define WINWD 4
 230 #define WINLIM (1 << WINWD)
 231 #define WINMASK (WINLIM - 1)
 232 #define TABSZ (WINLIM/2 + 1)
 233
 234   f25519 VX[TABSZ], VY[TABSZ], VZ[TABSZ];
 235   f25519 TX, TY, TZ, UX, UY, UZ;
 236   unsigned i, j, k, w;
 237   uint32 m_neg;
 238   scaf_piece ni;
 239
 240   /* Build a table of small multiples. */
 241   f25519_set(&VX[0], 0); f25519_set(&VY[0], 1); f25519_set(&VZ[0], 1);
 242   VX[1] = *X0; VY[1] = *Y0; VZ[1] = *Z0;
 243   ptdbl(&VX[2], &VY[2], &VZ[2], &VX[1], &VY[1], &VZ[1]);
 244   for (i = 3; i < TABSZ; i += 2) {
 245     ptadd(&VX[i], &VY[i], &VZ[i],
 246           &VX[i - 1], &VY[i - 1], &VZ[i - 1], X0, Y0, Z0);
 247     ptdbl(&VX[i + 1], &VY[i + 1], &VZ[i + 1],
 248           &VX[(i + 1)/2], &VY[(i + 1)/2], &VZ[(i + 1)/2]);
 249   }
 250
 251   /* Now do the multiplication.  We lag a window behind the cursor position
 252    * because of the scalar recoding we do.
 253    */
 254   f25519_set(&TX, 0); f25519_set(&TY, 1); f25519_set(&TZ, 1);
 255   for (i = NPIECE, w = 0, m_neg = 0; i--; ) {
 256     ni = n[i];
 257
 258     /* Work through each window in the scalar piece. */
 259     for (j = 0; j < PIECEWD; j += WINWD) {
 260
 261       /* Shift along by a window. */
 262       for (k = 0; k < WINWD; k++) ptdbl(&TX, &TY, &TZ, &TX, &TY, &TZ);
 263
 264       /* Peek at the next window of four bits.  If the top bit is set we lend
 265        * a bit leftwards, into w.  It's too late for this to affect the sign
 266        * now, but if we negated earlier then the addition would be wrong.
 267        */
 268       w += (ni >> (PIECEWD - 1))&0x1u;
 269       w = ((WINLIM - w)&m_neg) | (w&~m_neg);
 270
 271       /* Collect the entry from the table, and add or subtract. */
 272       f25519_pickn(&UX, VX, TABSZ, w);
 273       f25519_pickn(&UY, VY, TABSZ, w);
 274       f25519_pickn(&UZ, VZ, TABSZ, w);
 275       f25519_condneg(&UX, &UX, m_neg);
 276       ptadd(&TX, &TY, &TZ, &TX, &TY, &TZ, &UX, &UY, &UZ);
 277
 278       /* Move the next window into the delay slot.  If its top bit is set,
 279        * then negate it and set m_neg.
 280        */
 281       w = (ni >> (PIECEWD - WINWD))&WINMASK;
 282       m_neg = -(uint32)((w >> (WINWD - 1))&0x1u);
 283       ni <<= WINWD;
 284     }
 285   }
 286
 287   /* Do the final window.  Just fix the sign and go. */
 288   for (k = 0; k < WINWD; k++) ptdbl(&TX, &TY, &TZ, &TX, &TY, &TZ);
 289   w = ((WINLIM - w)&m_neg) | (w&~m_neg);
 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(X, Y, Z, &TX, &TY, &TZ, &UX, &UY, &UZ);
 295
 296 #undef WINWD
 297 #undef WINLIM
 298 #undef WINMASK
 299 #undef TABSZ
 300 }
 301
 302 static void ptsimmul(f25519 *X, f25519 *Y, f25519 *Z,
 303                      const scaf_piece n0[NPIECE],
 304                      const f25519 *X0, const f25519 *Y0, const f25519 *Z0,
 305                      const scaf_piece n1[NPIECE],
 306                      const f25519 *X1, const f25519 *Y1, const f25519 *Z1)
 307 {
 308   /* We assume that the window width divides the scalar piece width. */
 309 #define WINWD 2
 310 #define WINLIM (1 << WINWD)
 311 #define WINMASK (WINLIM - 1)
 312 #define TABSZ (1 << 2*WINWD)
 313
 314   f25519 VX[TABSZ], VY[TABSZ], VZ[TABSZ];
 315   f25519 TX, TY, TZ, UX, UY, UZ;
 316   unsigned i, j, k, w, ni0, ni1;
 317
 318   /* Build a table of small linear combinations. */
 319   f25519_set(&VX[0], 0); f25519_set(&VY[0], 1); f25519_set(&VZ[0], 1);
 320   VX[1] = *X0; VX[WINLIM] = *X1;
 321   VY[1] = *Y0; VY[WINLIM] = *Y1;
 322   VZ[1] = *Z0; VZ[WINLIM] = *Z1;
 323   for (i = 2; i < WINLIM; i <<= 1) {
 324     ptdbl(&VX[i], &VY[i], &VZ[i],
 325           &VX[i/2], &VY[i/2], &VZ[i/2]);
 326     ptdbl(&VX[i*WINLIM], &VY[i*WINLIM], &VZ[i*WINLIM],
 327           &VX[i*WINLIM/2], &VY[i*WINLIM/2], &VZ[i*WINLIM/2]);
 328   }
 329   for (i = 2; i < TABSZ; i <<= 1) {
 330     for (j = 1; j < i; j++)
 331       ptadd(&VX[i + j], &VY[i + j], &VZ[i + j],
 332             &VX[i], &VY[i], &VZ[i], &VX[j], &VY[j], &VZ[j]);
 333   }
 334
 335   /* Do the multiplication. */
 336   f25519_set(&TX, 0); f25519_set(&TY, 1); f25519_set(&TZ, 1);
 337   for (i = NPIECE; i--; ) {
 338     ni0 = n0[i]; ni1 = n1[i];
 339
 340     /* Work through each window in the scalar pieces. */
 341     for (j = 0; j < PIECEWD; j += WINWD) {
 342
 343       /* Shift along by a window. */
 344       for (k = 0; k < WINWD; k++) ptdbl(&TX, &TY, &TZ, &TX, &TY, &TZ);
 345
 346       /* Collect the next window from the scalars. */
 347       w = ((ni0 >> (PIECEWD - WINWD))&WINMASK) |
 348         ((ni1 >> (PIECEWD - 2*WINWD))&(WINMASK << WINWD));
 349       ni0 <<= WINWD; ni1 <<= WINWD;
 350
 351       /* Collect the entry from the table, and add. */
 352       f25519_pickn(&UX, VX, TABSZ, w);
 353       f25519_pickn(&UY, VY, TABSZ, w);
 354       f25519_pickn(&UZ, VZ, TABSZ, w);
 355       ptadd(&TX, &TY, &TZ, &TX, &TY, &TZ, &UX, &UY, &UZ);
 356     }
 357   }
 358
 359   /* Done. */
 360   *X = TX; *Y = TY; *Z = TZ;
 361 }
 362
 363 /*----- Key derivation utilities ------------------------------------------*/
 364
 365 static void unpack_key(scaf_piece a[NPIECE], octet h1[32],
 366                        const octet *k, size_t ksz)
 367 {
 368   sha512_ctx h;
 369   octet b[SHA512_HASHSZ];
 370
 371   sha512_init(&h); sha512_hash(&h, k, ksz); sha512_done(&h, b);
 372   b[0] &= 0xf8u; b[31] = (b[31]&0x3f) | 0x40;
 373   scaf_load(a, b, 32, NPIECE, PIECEWD);
 374   memcpy(h1, b + 32, 32);
 375 }
 376
 377 /*----- Main code ---------------------------------------------------------*/
 378
 379 /* --- @ed25519_pubkey@ --- *
 380  *
 381  * Arguments:   @octet K[ED25519_PUBSZ]@ = where to put the public key
 382  *              @const void *k@ = private key
 383  *              @size_t ksz@ = length of private key
 384  *
 385  * Returns:     ---
 386  *
 387  * Use:         Derives the public key from a private key.
 388  */
 389
 390 void ed25519_pubkey(octet K[ED25519_PUBSZ], const void *k, size_t ksz)
 391 {
 392   scaf_piece a[NPIECE];
 393   f25519 AX, AY, AZ;
 394   octet h1[32];
 395
 396   unpack_key(a, h1, k, ksz);
 397   ptmul(&AX, &AY, &AZ, a, BX, BY, BZ);
 398   ptencode(K, &AX, &AY, &AZ);
 399 }
 400
 401 /* --- @ed25519_sign@ --- *
 402  *
 403  * Arguments:   @octet sig[ED25519_SIGSZ]@ = where to put the signature
 404  *              @const void *k@ = private key
 405  *              @size_t ksz@ = length of private key
 406  *              @const octet K[ED25519_PUBSZ]@ = public key
 407  *              @const void *m@ = message to sign
 408  *              @size_t msz@ = length of message
 409  *
 410  * Returns:     ---
 411  *
 412  * Use:         Signs a message.
 413  */
 414
 415 void ed25519_sign(octet sig[ED25519_SIGSZ],
 416                   const void *k, size_t ksz,
 417                   const octet K[ED25519_PUBSZ],
 418                   const void *m, size_t msz)
 419 {
 420   sha512_ctx h;
 421   scaf_piece a[NPIECE], r[NPIECE], t[NPIECE], scratch[3*NPIECE + 1];
 422   scaf_dblpiece tt[2*NPIECE];
 423   f25519 RX, RY, RZ;
 424   octet h1[32], b[SHA512_HASHSZ];
 425   unsigned i;
 426
 427   /* Get my private key. */
 428   unpack_key(a, h1, k, ksz);
 429
 430   /* Select the nonce and the vector part. */
 431   sha512_init(&h);
 432   sha512_hash(&h, h1, 32);
 433   sha512_hash(&h, m, msz);
 434   sha512_done(&h, b);
 435   scaf_loaddbl(tt, b, 64, 2*NPIECE, PIECEWD);
 436   scaf_reduce(r, tt, l, mu, NPIECE, PIECEWD, scratch);
 437   ptmul(&RX, &RY, &RZ, r, BX, BY, BZ);
 438   ptencode(sig, &RX, &RY, &RZ);
 439
 440   /* Calculate the scalar part. */
 441   sha512_init(&h);
 442   sha512_hash(&h, sig, 32);
 443   sha512_hash(&h, K, 32);
 444   sha512_hash(&h, m, msz);
 445   sha512_done(&h, b);
 446   scaf_loaddbl(tt, b, 64, 2*NPIECE, PIECEWD);
 447   scaf_reduce(t, tt, l, mu, NPIECE, PIECEWD, scratch);
 448   scaf_mul(tt, t, a, NPIECE);
 449   for (i = 0; i < NPIECE; i++) tt[i] += r[i];
 450   scaf_reduce(t, tt, l, mu, NPIECE, PIECEWD, scratch);
 451   scaf_store(sig + 32, 32, t, NPIECE, PIECEWD);
 452 }
 453
 454 /* --- @ed25519_verify@ --- *
 455  *
 456  * Arguments:   @const octet K[ED25519_PUBSZ]@ = public key
 457  *              @const void *m@ = message to sign
 458  *              @size_t msz@ = length of message
 459  *              @const octet sig[ED25519_SIGSZ]@ = signature
 460  *
 461  * Returns:     Zero if OK, negative on failure.
 462  *
 463  * Use:         Verify a signature.
 464  */
 465
 466 int ed25519_verify(const octet K[ED25519_PUBSZ],
 467                    const void *m, size_t msz,
 468                    const octet sig[ED25519_SIGSZ])
 469 {
 470   sha512_ctx h;
 471   scaf_piece s[NPIECE], t[NPIECE], scratch[3*NPIECE + 1];
 472   scaf_dblpiece tt[2*NPIECE];
 473   f25519 AX, AY, AZ, RX, RY, RZ;
 474   octet b[SHA512_HASHSZ];
 475
 476   /* Unpack the public key.  Negate it: we're meant to subtract the term
 477    * involving the public key point, and this is easier than negating the
 478    * scalar.
 479    */
 480   if (ptdecode(&AX, &AY, &AZ, K)) return (-1);
 481   f25519_neg(&AX, &AX);
 482
 483   /* Check the signature. */
 484   sha512_init(&h);
 485   sha512_hash(&h, sig, 32);
 486   sha512_hash(&h, K, 32);
 487   sha512_hash(&h, m, msz);
 488   sha512_done(&h, b);
 489   scaf_load(s, sig + 32, 32, NPIECE, PIECEWD);
 490   scaf_loaddbl(tt, b, 64, 2*NPIECE, PIECEWD);
 491   scaf_reduce(t, tt, l, mu, NPIECE, PIECEWD, scratch);
 492   ptsimmul(&RX, &RY, &RZ, s, BX, BY, BZ, t, &AX, &AY, &AZ);
 493   ptencode(b, &RX, &RY, &RZ);
 494   if (memcmp(b, sig, 32) != 0) return (-1);
 495
 496   /* All is good. */
 497   return (0);
 498 }
 499
 500 /*----- Test rig ----------------------------------------------------------*/
 501
 502 #ifdef TEST_RIG
 503
 504 #include <stdio.h>
 505 #include <string.h>
 506
 507 #include <mLib/report.h>
 508 #include <mLib/testrig.h>
 509
 510 static int vrf_pubkey(dstr dv[])
 511 {
 512   dstr dpub = DSTR_INIT;
 513   int ok = 1;
 514
 515   if (dv[1].len != 32) die(1, "bad pub length");
 516
 517   dstr_ensure(&dpub, 32); dpub.len = 32;
 518   ed25519_pubkey((octet *)dpub.buf, dv[0].buf, dv[0].len);
 519   if (memcmp(dpub.buf, dv[1].buf, 64) != 0) {
 520     ok = 0;
 521     fprintf(stderr, "failed!");
 522     fprintf(stderr, "\n\tpriv = "); type_hex.dump(&dv[0], stderr);
 523     fprintf(stderr, "\n\tcalc = "); type_hex.dump(&dpub, stderr);
 524     fprintf(stderr, "\n\twant = "); type_hex.dump(&dv[1], stderr);
 525     fprintf(stderr, "\n");
 526   }
 527
 528   dstr_destroy(&dpub);
 529   return (ok);
 530 }
 531
 532 static int vrf_sign(dstr dv[])
 533 {
 534   octet K[ED25519_PUBSZ];
 535   dstr dsig = DSTR_INIT;
 536   int ok = 1;
 537
 538   if (dv[2].len != 64) die(1, "bad result length");
 539
 540   dstr_ensure(&dsig, 64); dsig.len = 64;
 541   ed25519_pubkey(K, dv[0].buf, dv[0].len);
 542   ed25519_sign((octet *)dsig.buf, dv[0].buf, dv[0].len, K,
 543                dv[1].buf, dv[1].len);
 544   if (memcmp(dsig.buf, dv[2].buf, 64) != 0) {
 545     ok = 0;
 546     fprintf(stderr, "failed!");
 547     fprintf(stderr, "\n\tpriv = "); type_hex.dump(&dv[0], stderr);
 548     fprintf(stderr, "\n\t msg = "); type_hex.dump(&dv[1], stderr);
 549     fprintf(stderr, "\n\tcalc = "); type_hex.dump(&dsig, stderr);
 550     fprintf(stderr, "\n\twant = "); type_hex.dump(&dv[2], stderr);
 551     fprintf(stderr, "\n");
 552   }
 553
 554   dstr_destroy(&dsig);
 555   return (ok);
 556 }
 557
 558 static int vrf_verify(dstr dv[])
 559 {
 560   int rc_want, rc_calc;
 561   int ok = 1;
 562
 563   if (dv[0].len != 32) die(1, "bad pub length");
 564   if (dv[2].len != 64) die(1, "bad sig length");
 565   rc_want = *(int *)dv[3].buf;
 566
 567   rc_calc = ed25519_verify((const octet *)dv[0].buf,
 568                            dv[1].buf, dv[1].len,
 569                            (const octet *)dv[2].buf);
 570   if (!rc_want != !rc_calc) {
 571     ok = 0;
 572     fprintf(stderr, "failed!");
 573     fprintf(stderr, "\n\t pub = "); type_hex.dump(&dv[0], stderr);
 574     fprintf(stderr, "\n\t msg = "); type_hex.dump(&dv[1], stderr);
 575     fprintf(stderr, "\n\t sig = "); type_hex.dump(&dv[2], stderr);
 576     fprintf(stderr, "\n\tcalc = %d", rc_calc);
 577     fprintf(stderr, "\n\twant = %d", rc_want);
 578     fprintf(stderr, "\n");
 579   }
 580
 581   return (ok);
 582 }
 583
 584 static test_chunk tests[] = {
 585   { "pubkey", vrf_pubkey, { &type_hex, &type_hex } },
 586   { "sign", vrf_sign, { &type_hex, &type_hex, &type_hex } },
 587   { "verify", vrf_verify, { &type_hex, &type_hex, &type_hex, &type_int } },
 588   { 0, 0, { 0 } }
 589 };
 590
 591 int main(int argc, char *argv[])
 592 {
 593   test_run(argc, argv, tests, SRCDIR "/t/ed25519");
 594   return (0);
 595 }
 596
 597 #endif
 598
 599 /*----- That's all, folks -------------------------------------------------*/