| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: field.c,v 1.3 2004/04/01 12:50:09 mdw Exp $ |
| 4 | * |
| 5 | * Abstract field operations |
| 6 | * |
| 7 | * (c) 2001 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: field.c,v $ |
| 33 | * Revision 1.3 2004/04/01 12:50:09 mdw |
| 34 | * Add cyclic group abstraction, with test code. Separate off exponentation |
| 35 | * functions for better static linking. Fix a buttload of bugs on the way. |
| 36 | * Generally ensure that negative exponents do inversion correctly. Add |
| 37 | * table of standard prime-field subgroups. (Binary field subgroups are |
| 38 | * currently unimplemented but easy to add if anyone ever finds a good one.) |
| 39 | * |
| 40 | * Revision 1.2 2004/03/21 22:52:06 mdw |
| 41 | * Merge and close elliptic curve branch. |
| 42 | * |
| 43 | * Revision 1.1.4.1 2003/06/10 13:43:53 mdw |
| 44 | * Simple (non-projective) curves over prime fields now seem to work. |
| 45 | * |
| 46 | * Revision 1.1 2001/05/07 17:30:13 mdw |
| 47 | * Add an internal-representation no-op function. |
| 48 | * |
| 49 | */ |
| 50 | |
| 51 | /*----- Header files ------------------------------------------------------*/ |
| 52 | |
| 53 | #include "field.h" |
| 54 | #include "mp.h" |
| 55 | |
| 56 | /*----- Main code ---------------------------------------------------------*/ |
| 57 | |
| 58 | /* --- @field_id@ --- * |
| 59 | * |
| 60 | * Arguments: @field *f@ = pointer to a field |
| 61 | * @mp *d@ = a destination element |
| 62 | * @mp *x@ = a source element |
| 63 | * |
| 64 | * Returns: The result element. |
| 65 | * |
| 66 | * Use: An identity operation which can be used if your field has no |
| 67 | * internal representation. |
| 68 | */ |
| 69 | |
| 70 | mp *field_id(field *f, mp *d, mp *x) |
| 71 | { |
| 72 | x = MP_COPY(x); |
| 73 | if (d) MP_DROP(d); |
| 74 | return (x); |
| 75 | } |
| 76 | |
| 77 | /* --- @field_samep@ --- * |
| 78 | * |
| 79 | * Arguments: @field *f, *g@ = two fields |
| 80 | * |
| 81 | * Returns: Nonzero if the fields are identical (not just isomorphic). |
| 82 | * |
| 83 | * Use: Checks for sameness of fields. This function does the full |
| 84 | * check, not just the field-type-specific check done by the |
| 85 | * @sampep@ field operation. |
| 86 | */ |
| 87 | |
| 88 | int field_samep(field *f, field *g) |
| 89 | { |
| 90 | return (f->ops == g->ops && F_SAMEP(f, g)); |
| 91 | } |
| 92 | |
| 93 | /* --- @field_stdsamep@ --- * |
| 94 | * |
| 95 | * Arguments: @field *f, *g@ = two fields |
| 96 | * |
| 97 | * Returns: Nonzero if the fields are identical (not just isomorphic). |
| 98 | * |
| 99 | * Use: Standard sameness check, based on equality of the @m@ |
| 100 | * member. |
| 101 | */ |
| 102 | |
| 103 | int field_stdsamep(field *f, field *g) |
| 104 | { |
| 105 | return (MP_EQ(f->m, g->m)); |
| 106 | } |
| 107 | |
| 108 | /*----- That's all, folks -------------------------------------------------*/ |