~mdw / secnet / blame
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|---|---|---|
| 8a7654a6 MW |
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 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 | /*----- Header files ------------------------------------------------------*/ | |
| 48 | ||
| 49 | #include "fake-mLib-bits.h" | |
| 50 | ||
| 51 | #include "montladder.h" | |
| 52 | #include "fgoldi.h" | |
| 53 | #include "x448.h" | |
| 54 | ||
| 55 | /*----- Important constants -----------------------------------------------*/ | |
| 56 | ||
| 57 | const octet x448_base[56] = { 5, 0, /* ... */ }; | |
| 58 | ||
| 59 | #define A0 39081 | |
| 60 | ||
| 61 | /*----- Main code ---------------------------------------------------------*/ | |
| 62 | ||
| 63 | /* --- @x448@ --- * | |
| 64 | * | |
| 65 | * Arguments: @octet zz[X448_OUTSZ]@ = where to put the result | |
| 66 | * @const octet k[X448_KEYSZ]@ = pointer to private key | |
| 67 | * @const octet qx[X448_PUBSZ]@ = pointer to public value | |
| 68 | * | |
| 69 | * Returns: --- | |
| 70 | * | |
| 71 | * Use: Calculates X448 of @k@ and @qx@. | |
| 72 | */ | |
| 73 | ||
| 74 | void x448(octet zz[X448_OUTSZ], | |
| 75 | const octet k[X448_KEYSZ], | |
| 76 | const octet qx[X448_PUBSZ]) | |
| 77 | { | |
| 78 | uint32 kw[14]; | |
| 79 | fgoldi x1; | |
| 80 | unsigned i; | |
| 81 | ||
| 82 | /* Load and clamp the key. The low bits are cleared to kill the small | |
| 83 | * subgroups on the curve and its twist, and a high bit is set to guard | |
| 84 | * against careless implementations, though this isn't one of those. | |
| 85 | */ | |
| 86 | for (i = 0; i < 14; i++) kw[i] = LOAD32_L(k + 4*i); | |
| 87 | kw[0] &= 0xfffffffc; kw[13] |= 0x80000000; | |
| 88 | ||
| 89 | /* And run the ladder. */ | |
| 90 | fgoldi_load(&x1, qx); | |
| 91 | #define MULA0(z, x) do { fgoldi_mulconst((z), (x), A0); } while (0) | |
| 92 | MONT_LADDER(fgoldi, MULA0, kw, 14, 32, &x1, &x1); | |
| 93 | #undef MULA0 | |
| 94 | fgoldi_store(zz, &x1); | |
| 95 | } | |
| 96 | ||
| 97 | /*----- That's all, folks -------------------------------------------------*/ |