| 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 | #ifndef CATACOMB_EC_RAW_H |
| 29 | #define CATACOMB_EC_RAW_H |
| 30 | |
| 31 | #ifdef __cplusplus |
| 32 | extern "C" { |
| 33 | #endif |
| 34 | |
| 35 | /*----- Header files ------------------------------------------------------*/ |
| 36 | |
| 37 | #ifndef CATACOMB_BUF_H |
| 38 | # include "buf.h" |
| 39 | #endif |
| 40 | |
| 41 | #ifndef CATACOMB_EC_H |
| 42 | # include "ec.h" |
| 43 | #endif |
| 44 | |
| 45 | /*----- Data formatting ---------------------------------------------------*/ |
| 46 | |
| 47 | /* EC2OSP/OS2ECP bit mask. */ |
| 48 | #define EC_YBIT 1u /* The compressed @y@-coordinate */ |
| 49 | #define EC_XONLY 1u /* The @y@-coordinate is absent */ |
| 50 | #define EC_CMPR 2u /* Compressed @y@-coordinate */ |
| 51 | #define EC_LSB 2u /* Use `lsb' compression */ |
| 52 | #define EC_EXPLY 4u /* Explicit @y@-coordinate */ |
| 53 | #define EC_SORT 8u /* Use `sort' rather than `lsb' */ |
| 54 | |
| 55 | /* --- @ec_ec2osp@ --- * |
| 56 | * |
| 57 | * Arguments: @ec_curve *c@ = elliptic curve |
| 58 | * @unsigned f@ = format flags for output |
| 59 | * @buf *b@ = pointer to a buffer |
| 60 | * @const ec *p@ = an elliptic curve point |
| 61 | * |
| 62 | * Returns: Zero on success, nonzero on failure. |
| 63 | * |
| 64 | * Use: Puts an elliptic curve point to the given buffer using the |
| 65 | * standard uncompressed format described in P1363 and SEC1. |
| 66 | * This requires at most @1 + 2 * c->f->noctets@ space in the |
| 67 | * buffer. |
| 68 | * |
| 69 | * Point compression features are determined by @f@ as follows. |
| 70 | * If @EC_CMPR@ is set then point compression is performed and a |
| 71 | * compressed form of the %$y$%-coordinate is contained in the |
| 72 | * first output byte; if @EC_SORT@ is set then P1363a `SORT' |
| 73 | * compression is used, otherwise LSB compression. If |
| 74 | * @EC_EXPLY@ is set, then an explicit %$y$%-coordinate is |
| 75 | * output in full. Otherwise the %$y$%-coordinate is |
| 76 | * suppressed. |
| 77 | * |
| 78 | * Returns failure (@-1@) if the flags are invalid, or if there |
| 79 | * isn't enough space in the output buffer. |
| 80 | */ |
| 81 | |
| 82 | extern int ec_ec2osp(ec_curve */*c*/, unsigned /*f*/, |
| 83 | buf */*b*/, const ec */*p*/); |
| 84 | |
| 85 | /* --- @ec_os2ecp@ --- * |
| 86 | * |
| 87 | * Arguments: @ec_curve *c = elliptic curve |
| 88 | * @unsigned f@ = format flags for input |
| 89 | * @buf *b@ = pointer to a buffer |
| 90 | * @ec *d@ = an elliptic curve point |
| 91 | * |
| 92 | * Returns: Zero on success, nonzero on failure. |
| 93 | * |
| 94 | * Use: Reads an elliptic curve point from the given buffer using the |
| 95 | * standard uncompressed format described in P1363 and SEC1. |
| 96 | * |
| 97 | * Point compression features are determined by @f@ as follows. |
| 98 | * If @EC_LSB@ is set, then accept an LSB-compressed %$y$%- |
| 99 | * coordinate; if @EC_SORT@ is set, then accept a SORT- |
| 100 | * compressed %$y$%-coordinate; if @EC_EXPLY@ is set, then |
| 101 | * accept an explicit %$y$%-coordinate; if @EC_XONLY@ is set |
| 102 | * then accept a bare %$x$%-coordinate (a correct |
| 103 | * %$y$%-coordinate is chosen arbitrarily). Hybrid forms are |
| 104 | * acceptable, and the input is checked to verify that the |
| 105 | * redundant representations are consistent. If no flags are |
| 106 | * set in @f@, then no input (other than the point at infinity) |
| 107 | * will be acceptable. |
| 108 | */ |
| 109 | |
| 110 | extern int ec_os2ecp(ec_curve */*c*/, unsigned /*f*/, buf */*b*/, ec */*d*/); |
| 111 | |
| 112 | /* --- @ec_putraw@ --- * |
| 113 | * |
| 114 | * Arguments: @ec_curve *c@ = elliptic curve |
| 115 | * @buf *b@ = pointer to a buffer |
| 116 | * @const ec *p@ = an elliptic curve point |
| 117 | * |
| 118 | * Returns: Zero on success, nonzero on failure. |
| 119 | * |
| 120 | * Use: Puts an elliptic curve point to the given buffer using the |
| 121 | * standard uncompressed format described in P1383 and SEC1. |
| 122 | * We don't do point compression. |
| 123 | */ |
| 124 | |
| 125 | extern int ec_putraw(ec_curve */*c*/, buf */*b*/, const ec */*p*/); |
| 126 | |
| 127 | /* --- @ec_getraw@ --- * |
| 128 | * |
| 129 | * Arguments: @ec_curve *c@ = elliptic curve |
| 130 | * @buf *b@ = pointer to a buffer |
| 131 | * @ec *d@ = an elliptic curve point |
| 132 | * |
| 133 | * Returns: Zero on success, nonzero on failure. |
| 134 | * |
| 135 | * Use: Reads an elliptic curve point from the given buffer using the |
| 136 | * standard uncompressed format described in P1383 and SEC1. |
| 137 | * We don't do point compression. |
| 138 | */ |
| 139 | |
| 140 | extern int ec_getraw(ec_curve */*c*/, buf */*b*/, ec */*d*/); |
| 141 | |
| 142 | /*----- That's all, folks -------------------------------------------------*/ |
| 143 | |
| 144 | #ifdef __cplusplus |
| 145 | } |
| 146 | #endif |
| 147 | |
| 148 | #endif |