| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * Raw formatting of elliptic curve points |
| 4 | * |
| 5 | * (c) 2004 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 "ec.h" |
| 31 | #include "ec-raw.h" |
| 32 | |
| 33 | /*----- Main code ---------------------------------------------------------*/ |
| 34 | |
| 35 | /* --- @ec_putraw@ --- * |
| 36 | * |
| 37 | * Arguments: @ec_curve *c@ = elliptic curve |
| 38 | * @buf *b@ = pointer to a buffer |
| 39 | * @const ec *p@ = an elliptic curve point |
| 40 | * |
| 41 | * Returns: Zero on success, nonzero on failure. |
| 42 | * |
| 43 | * Use: Puts an elliptic curve point to the given buffer using the |
| 44 | * standard uncompressed format described in P1383 and SEC1. |
| 45 | * This requires at most @1 + 2 * c->f->noctets@ space in the |
| 46 | * buffer. We don't do point compression. |
| 47 | */ |
| 48 | |
| 49 | int ec_putraw(ec_curve *c, buf *b, const ec *p) |
| 50 | { |
| 51 | octet *q; |
| 52 | size_t n; |
| 53 | |
| 54 | if (EC_ATINF(p)) return (buf_putbyte(b, 0)); |
| 55 | buf_putbyte(b, 4); |
| 56 | n = c->f->noctets; |
| 57 | if ((q = buf_get(b, n * 2)) == 0) return (-1); |
| 58 | mp_storeb(p->x, q, n); |
| 59 | mp_storeb(p->y, q + n, n); |
| 60 | return (0); |
| 61 | } |
| 62 | |
| 63 | /* --- @ec_getraw@ --- * |
| 64 | * |
| 65 | * Arguments: @ec_curve *c@ = elliptic curve |
| 66 | * @buf *b@ = pointer to a buffer |
| 67 | * @ec *d@ = an elliptic curve point |
| 68 | * |
| 69 | * Returns: Zero on success, nonzero on failure. |
| 70 | * |
| 71 | * Use: Reads an elliptic curve point from the given buffer using the |
| 72 | * standard uncompressed format described in P1383 and SEC1. |
| 73 | * We don't do point compression. |
| 74 | */ |
| 75 | |
| 76 | int ec_getraw(ec_curve *c, buf *b, ec *d) |
| 77 | { |
| 78 | const octet *q; |
| 79 | size_t n; |
| 80 | int u; |
| 81 | |
| 82 | if ((u = buf_getbyte(b)) < 0) return (-1); |
| 83 | if (!u) { EC_SETINF(d); return (0); } |
| 84 | if (!(u & 4)) return (-1); |
| 85 | n = c->f->noctets; |
| 86 | if ((q = buf_get(b, n * 2)) == 0) return (-1); |
| 87 | EC_DESTROY(d); |
| 88 | d->x = mp_loadb(MP_NEW, q, n); |
| 89 | d->y = mp_loadb(MP_NEW, q + n, n); |
| 90 | d->z = 0; |
| 91 | return (0); |
| 92 | } |
| 93 | |
| 94 | /*----- That's all, folks -------------------------------------------------*/ |