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1 | /* -*-c-*- |
2 | * |
3 | * $Id: ec-raw.c,v 1.1 2004/04/04 19:04:11 mdw Exp $ |
4 | * |
5 | * Raw formatting of elliptic curve points |
6 | * |
7 | * (c) 2004 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
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. |
18 | * |
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. |
23 | * |
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 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: ec-raw.c,v $ |
33 | * Revision 1.1 2004/04/04 19:04:11 mdw |
34 | * Raw I/O of elliptic curve points and group elements. |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include "ec.h" |
41 | #include "ec-raw.h" |
42 | |
43 | /*----- Main code ---------------------------------------------------------*/ |
44 | |
45 | /* --- @ec_putraw@ --- * |
46 | * |
47 | * Arguments: @ec_curve *c@ = elliptic curve |
48 | * @buf *b@ = pointer to a buffer |
49 | * @const ec *p@ = an elliptic curve point |
50 | * |
51 | * Returns: Zero on success, nonzero on failure. |
52 | * |
53 | * Use: Puts an elliptic curve point to the given buffer using the |
54 | * standard uncompressed format described in P1383 and SEC1. |
55 | * This requires at most @1 + 2 * c->f->noctets@ space in the |
56 | * buffer. We don't do point compression. |
57 | */ |
58 | |
59 | int ec_putraw(ec_curve *c, buf *b, const ec *p) |
60 | { |
61 | octet *q; |
62 | size_t n; |
63 | |
64 | if (EC_ATINF(p)) return (buf_putbyte(b, 0)); |
65 | buf_putbyte(b, 4); |
66 | n = c->f->noctets; |
67 | if ((q = buf_get(b, n * 2)) == 0) return (-1); |
68 | mp_storeb(p->x, q, n); |
69 | mp_storeb(p->y, q + n, n); |
70 | return (0); |
71 | } |
72 | |
73 | /* --- @ec_getraw@ --- * |
74 | * |
75 | * Arguments: @ec_curve *c@ = elliptic curve |
76 | * @buf *b@ = pointer to a buffer |
77 | * @ec *d@ = an elliptic curve point |
78 | * |
79 | * Returns: Zero on success, nonzero on failure. |
80 | * |
81 | * Use: Reads an elliptic curve point from the given buffer using the |
82 | * standard uncompressed format described in P1383 and SEC1. |
83 | * We don't do point compression. |
84 | */ |
85 | |
86 | int ec_getraw(ec_curve *c, buf *b, ec *d) |
87 | { |
88 | const octet *q; |
89 | size_t n; |
90 | int u; |
91 | |
92 | if ((u = buf_getbyte(b)) < 0) return (-1); |
93 | if (!u) { EC_SETINF(d); return (0); } |
94 | if (!(u & 4)) return (-1); |
95 | n = c->f->noctets; |
96 | if ((q = buf_get(b, n * 2)) == 0) return (-1); |
97 | EC_DESTROY(d); |
98 | d->x = mp_loadb(MP_NEW, q, n); |
99 | d->y = mp_loadb(MP_NEW, q + n, n); |
100 | d->z = 0; |
101 | return (0); |
102 | } |
103 | |
104 | /*----- That's all, folks -------------------------------------------------*/ |