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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: ec-raw.c,v 1.2 2004/04/08 01:36:15 mdw Exp $ |
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4 | * |
5 | * Raw formatting of elliptic curve points |
6 | * |
7 | * (c) 2004 Straylight/Edgeware |
8 | */ |
9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
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18 | * |
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19 | * Catacomb is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
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23 | * |
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24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with Catacomb; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
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30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include "ec.h" |
33 | #include "ec-raw.h" |
34 | |
35 | /*----- Main code ---------------------------------------------------------*/ |
36 | |
37 | /* --- @ec_putraw@ --- * |
38 | * |
39 | * Arguments: @ec_curve *c@ = elliptic curve |
40 | * @buf *b@ = pointer to a buffer |
41 | * @const ec *p@ = an elliptic curve point |
42 | * |
43 | * Returns: Zero on success, nonzero on failure. |
44 | * |
45 | * Use: Puts an elliptic curve point to the given buffer using the |
46 | * standard uncompressed format described in P1383 and SEC1. |
47 | * This requires at most @1 + 2 * c->f->noctets@ space in the |
48 | * buffer. We don't do point compression. |
49 | */ |
50 | |
51 | int ec_putraw(ec_curve *c, buf *b, const ec *p) |
52 | { |
53 | octet *q; |
54 | size_t n; |
55 | |
56 | if (EC_ATINF(p)) return (buf_putbyte(b, 0)); |
57 | buf_putbyte(b, 4); |
58 | n = c->f->noctets; |
59 | if ((q = buf_get(b, n * 2)) == 0) return (-1); |
60 | mp_storeb(p->x, q, n); |
61 | mp_storeb(p->y, q + n, n); |
62 | return (0); |
63 | } |
64 | |
65 | /* --- @ec_getraw@ --- * |
66 | * |
67 | * Arguments: @ec_curve *c@ = elliptic curve |
68 | * @buf *b@ = pointer to a buffer |
69 | * @ec *d@ = an elliptic curve point |
70 | * |
71 | * Returns: Zero on success, nonzero on failure. |
72 | * |
73 | * Use: Reads an elliptic curve point from the given buffer using the |
74 | * standard uncompressed format described in P1383 and SEC1. |
75 | * We don't do point compression. |
76 | */ |
77 | |
78 | int ec_getraw(ec_curve *c, buf *b, ec *d) |
79 | { |
80 | const octet *q; |
81 | size_t n; |
82 | int u; |
83 | |
84 | if ((u = buf_getbyte(b)) < 0) return (-1); |
85 | if (!u) { EC_SETINF(d); return (0); } |
86 | if (!(u & 4)) return (-1); |
87 | n = c->f->noctets; |
88 | if ((q = buf_get(b, n * 2)) == 0) return (-1); |
89 | EC_DESTROY(d); |
90 | d->x = mp_loadb(MP_NEW, q, n); |
91 | d->y = mp_loadb(MP_NEW, q + n, n); |
92 | d->z = 0; |
93 | return (0); |
94 | } |
95 | |
96 | /*----- That's all, folks -------------------------------------------------*/ |