mdw@git.distorted.org.uk Git - catacomb/blob - math/ec-raw.h

   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