mdw@git.distorted.org.uk Git - catacomb/blob - pub/x448.c

   1 /* -*-c-*-
   2  *
   3  * The X448 key-agreement algorithm
   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 <mLib/bits.h>
  31
  32 #include "montladder.h"
  33 #include "fgoldi.h"
  34 #include "x448.h"
  35
  36 /*----- Important constants -----------------------------------------------*/
  37
  38 const octet x448_base[56] = { 5, 0, /* ... */ };
  39
  40 #define A0 39081
  41
  42 /*----- Key fetching ------------------------------------------------------*/
  43
  44 const key_fetchdef x448_pubfetch[] = {
  45   { "pub",      offsetof(x448_pub, pub),        KENC_BINARY,    0 },
  46   { 0,          0,                              0,              0 }
  47 };
  48
  49 static const key_fetchdef priv[] = {
  50   { "priv",     offsetof(x448_priv, priv),      KENC_BINARY,    0 },
  51   { 0,          0,                              0,              0 }
  52 };
  53
  54 const key_fetchdef x448_privfetch[] = {
  55   { "pub",      offsetof(x448_priv, pub),       KENC_BINARY,    0 },
  56   { "private",  0,                              KENC_STRUCT,    priv },
  57   { 0,          0,                              0,              0 }
  58 };
  59
  60 /*----- Main code ---------------------------------------------------------*/
  61
  62 /* --- @x448@ --- *
  63  *
  64  * Arguments:   @octet zz[X448_OUTSZ]@ = where to put the result
  65  *              @const octet k[X448_KEYSZ]@ = pointer to private key
  66  *              @const octet qx[X448_PUBSZ]@ = pointer to public value
  67  *
  68  * Returns:     ---
  69  *
  70  * Use:         Calculates X448 of @k@ and @qx@.
  71  */
  72
  73 void x448(octet zz[X448_OUTSZ],
  74           const octet k[X448_KEYSZ],
  75           const octet qx[X448_PUBSZ])
  76 {
  77   uint32 kw[14];
  78   fgoldi x1;
  79   unsigned i;
  80
  81   /* Load and clamp the key.  The low bits are cleared to kill the small
  82    * subgroups on the curve and its twist, and a high bit is set to guard
  83    * against careless implementations, though this isn't one of those.
  84    */
  85   for (i = 0; i < 14; i++) kw[i] = LOAD32_L(k + 4*i);
  86   kw[0] &= 0xfffffffc; kw[13] |= 0x80000000;
  87
  88   /* And run the ladder. */
  89   fgoldi_load(&x1, qx);
  90 #define MULA0(z, x) do { fgoldi_mulconst((z), (x), A0); } while (0)
  91   MONT_LADDER(fgoldi, MULA0, kw, 14, 32, &x1, &x1);
  92 #undef MULA0
  93   fgoldi_store(zz, &x1);
  94 }
  95
  96 /*----- Test rig ----------------------------------------------------------*/
  97
  98 #ifdef TEST_RIG
  99
 100 #include <mLib/macros.h>
 101 #include <mLib/report.h>
 102 #include <mLib/testrig.h>
 103
 104 #include "ct.h"
 105
 106 static int vrf_x448(dstr dv[])
 107 {
 108   dstr dz = DSTR_INIT;
 109   int ok = 1;
 110
 111   if (dv[0].len != X448_KEYSZ) die(1, "bad key length");
 112   if (dv[1].len != X448_PUBSZ) die(1, "bad public length");
 113   if (dv[2].len != X448_OUTSZ) die(1, "bad result length");
 114
 115   ct_poison(dv[0].buf, dv[0].len);
 116   dstr_ensure(&dz, X448_OUTSZ); dz.len = X448_OUTSZ;
 117   x448((octet *)dz.buf,
 118        (const octet *)dv[0].buf,
 119        (const octet *)dv[1].buf);
 120   ct_remedy(dz.buf, dz.len);
 121   if (MEMCMP(dz.buf, !=, dv[2].buf, X448_OUTSZ)) {
 122     ok = 0;
 123     fprintf(stderr, "failed!");
 124     fprintf(stderr, "\n\t   k = "); type_hex.dump(&dv[0], stderr);
 125     fprintf(stderr, "\n\t   p = "); type_hex.dump(&dv[1], stderr);
 126     fprintf(stderr, "\n\twant = "); type_hex.dump(&dv[2], stderr);
 127     fprintf(stderr, "\n\tcalc = "); type_hex.dump(&dz, stderr);
 128     fprintf(stderr, "\n");
 129   }
 130
 131   dstr_destroy(&dz);
 132   return (ok);
 133 }
 134
 135 static int vrf_mct(dstr dv[])
 136 {
 137   octet b0[X448_OUTSZ], b1[X448_OUTSZ], *k = b0, *x = b1, *t;
 138   unsigned long i, niter;
 139   dstr d = DSTR_INIT;
 140   int ok = 1;
 141
 142   if (dv[0].len != sizeof(b0)) { fprintf(stderr, "k len\n"); exit(2); }
 143   if (dv[1].len != sizeof(b1)) { fprintf(stderr, "x len\n"); exit(2); }
 144   if (dv[3].len != sizeof(b0)) { fprintf(stderr, "result len\n"); exit(2); }
 145   memcpy(b0, dv[0].buf, sizeof(b0));
 146   memcpy(b1, dv[1].buf, sizeof(b1));
 147   niter = *(unsigned long *)dv[2].buf;
 148   dstr_ensure(&d, X448_OUTSZ); d.len = X448_OUTSZ; t = (octet *)d.buf;
 149
 150   for (i = 0; i < niter; i++) {
 151     x448(x, k, x);
 152     t = x; x = k; k = t;
 153   }
 154   memcpy(d.buf, k, d.len);
 155
 156   if (MEMCMP(d.buf, !=, dv[3].buf, d.len)) {
 157     ok = 0;
 158     fprintf(stderr, "failed...");
 159     fprintf(stderr, "\n\tinitial k = "); type_hex.dump(&dv[0], stderr);
 160     fprintf(stderr, "\n\tinitial x = "); type_hex.dump(&dv[1], stderr);
 161     fprintf(stderr, "\n\titerations = %lu", niter);
 162     fprintf(stderr, "\n\texpected = "); type_hex.dump(&dv[3], stderr);
 163     fprintf(stderr, "\n\tcalculated = "); type_hex.dump(&d, stderr);
 164     fputc('\n', stderr);
 165   }
 166
 167   dstr_destroy(&d);
 168   return (ok);
 169 }
 170
 171 static test_chunk tests[] = {
 172   { "x448", vrf_x448, { &type_hex, &type_hex, &type_hex } },
 173   { "x448-mct", vrf_mct,
 174     { &type_hex, &type_hex, &type_ulong, &type_hex } },
 175   { 0, 0, { 0 } }
 176 };
 177
 178 int main(int argc, char *argv[])
 179 {
 180   test_run(argc, argv, tests, SRCDIR "/t/x448");
 181   return (0);
 182 }
 183
 184 #endif
 185
 186 /*----- That's all, folks -------------------------------------------------*/