X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/391faf428ac513f9031c773016d79fdbe8b4653c..02d7884df1f33c9c7dc3a14c4b1a5f520ebe090a:/ec.h diff --git a/ec.h b/ec.h index 680bf9c..24bd6b2 100644 --- a/ec.h +++ b/ec.h @@ -1,6 +1,6 @@ /* -*-c-*- * - * $Id: ec.h,v 1.6 2004/03/22 02:19:10 mdw Exp $ + * $Id: ec.h,v 1.10 2004/04/03 03:32:05 mdw Exp $ * * Elliptic curve definitions * @@ -30,6 +30,22 @@ /*----- Revision history --------------------------------------------------* * * $Log: ec.h,v $ + * Revision 1.10 2004/04/03 03:32:05 mdw + * General robustification. + * + * Revision 1.9 2004/04/01 12:50:09 mdw + * Add cyclic group abstraction, with test code. Separate off exponentation + * functions for better static linking. Fix a buttload of bugs on the way. + * Generally ensure that negative exponents do inversion correctly. Add + * table of standard prime-field subgroups. (Binary field subgroups are + * currently unimplemented but easy to add if anyone ever finds a good one.) + * + * Revision 1.8 2004/03/27 17:54:11 mdw + * Standard curves and curve checking. + * + * Revision 1.7 2004/03/23 15:19:32 mdw + * Test elliptic curves more thoroughly. + * * Revision 1.6 2004/03/22 02:19:10 mdw * Rationalise the sliding-window threshold. Drop guarantee that right * arguments to EC @add@ are canonical, and fix up projective implementations @@ -71,8 +87,17 @@ /*----- Header files ------------------------------------------------------*/ -#include "field.h" -#include "mp.h" +#ifndef CATACOMB_FIELD_H +# include "field.h" +#endif + +#ifndef CATACOMB_MP_H +# include "mp.h" +#endif + +#ifndef CATACOMB_QDPARSE_H +# include "qdparse.h" +#endif /*----- Data structures ---------------------------------------------------*/ @@ -81,6 +106,7 @@ typedef struct ec_curve { const struct ec_ops *ops; /* Curve operations */ field *f; /* Underlying field structure */ + mp *a, *b; /* Standard params (internal form) */ } ec_curve; /* --- An elliptic curve point --- */ @@ -110,6 +136,7 @@ typedef struct ec_mulfactor { typedef struct ec_ops { void (*destroy)(ec_curve */*c*/); + int (*samep)(ec_curve */*c*/, ec_curve */*d*/); ec *(*in)(ec_curve */*c*/, ec */*d*/, const ec */*p*/); ec *(*out)(ec_curve */*c*/, ec */*d*/, const ec */*p*/); ec *(*fix)(ec_curve */*c*/, ec */*d*/, const ec */*p*/); @@ -121,6 +148,7 @@ typedef struct ec_ops { int (*check)(ec_curve */*c*/, const ec */*p*/); } ec_ops; +#define EC_SAMEP(c, d) (c)->ops->samep((c), (d)) #define EC_IN(c, d, p) (c)->ops->in((c), (d), (p)) #define EC_OUT(c, d, p) (c)->ops->out((c), (d), (p)) #define EC_FIX(c, d, p) (c)->ops->fix((c), (d), (p)) @@ -132,6 +160,15 @@ typedef struct ec_ops { #define EC_DBL(c, d, p) (c)->ops->dbl((c), (d), (p)) #define EC_CHECK(c, p) (c)->ops->check((c), (p)) +/* --- Elliptic curve parameters --- */ + +typedef struct ec_info { + ec_curve *c; /* The actual curve */ + ec g; /* The common point */ + mp *r; /* Order of %$g$% */ + mp *h; /* Cofactor %$h = \#E/r$% */ +} ec_info; + /*----- Simple memory management things -----------------------------------*/ /* --- @ec_create@ --- * @@ -235,8 +272,37 @@ extern ec *ec_setinf(ec */*p*/); extern ec *ec_copy(ec */*d*/, const ec */*p*/); +/* --- @ec_eq@ --- * + * + * Arguments: @const ec *p, *q@ = two points + * + * Returns: Nonzero if the points are equal. Compares external-format + * points. + */ + +#define EC_EQ(p, q) \ + ((EC_ATINF(p) && EC_ATINF(q)) || \ + (!EC_ATINF(p) && !EC_ATINF(q) && \ + MP_EQ((p)->x, (q)->x) && \ + MP_EQ((p)->y, (q)->y))) + +extern int ec_eq(const ec *p, const ec *q); + /*----- Interesting arithmetic --------------------------------------------*/ +/* --- @ec_samep@ --- * + * + * Arguments: @ec_curve *c, *d@ = two elliptic curves + * + * Returns: Nonzero if the curves are identical (not just isomorphic). + * + * Use: Checks for sameness of curves. This function does the full + * check, not just the curve-type-specific check done by the + * @sampep@ field operation. + */ + +extern int ec_samep(ec_curve */*c*/, ec_curve */*d*/); + /* --- @ec_find@ --- * * * Arguments: @ec_curve *c@ = pointer to an elliptic curve @@ -253,6 +319,19 @@ extern ec *ec_copy(ec */*d*/, const ec */*p*/); extern ec *ec_find(ec_curve */*c*/, ec */*d*/, mp */*x*/); +/* --- @ec_rand@ --- * + * + * Arguments: @ec_curve *c@ = pointer to an elliptic curve + * @ec *d@ = pointer to the destination point + * @grand *r@ = random number source + * + * Returns: The destination @d@. + * + * Use: Finds a random point on the given curve. + */ + +extern ec *ec_rand(ec_curve */*c*/, ec */*d*/, grand */*r*/); + /* --- @ec_neg@ --- * * * Arguments: @ec_curve *c@ = pointer to an elliptic curve @@ -356,6 +435,17 @@ extern ec *ec_immul(ec_curve */*c*/, ec */*d*/, /*----- Standard curve operations -----------------------------------------*/ +/* --- @ec_stdsamep@ --- * + * + * Arguments: @ec_curve *c, *d@ = two elliptic curves + * + * Returns: Nonzero if the curves are identical (not just isomorphic). + * + * Use: Simple sameness check on @a@ and @b@ curve members. + */ + +extern int ec_stdsamep(ec_curve */*c*/, ec_curve */*d*/); + /* --- @ec_idin@, @ec_idout@, @ec_idfix@ --- * * * Arguments: @ec_curve *c@ = pointer to an elliptic curve @@ -423,7 +513,7 @@ extern void ec_destroycurve(ec_curve */*c*/); * Arguments: @field *f@ = the underlying field for this elliptic curve * @mp *a, *b@ = the coefficients for this curve * - * Returns: A pointer to the curve. + * Returns: A pointer to the curve, or null. * * Use: Creates a curve structure for an elliptic curve defined over * a prime field. The @primeproj@ variant uses projective @@ -438,7 +528,7 @@ extern ec_curve *ec_primeproj(field */*f*/, mp */*a*/, mp */*b*/); * Arguments: @field *f@ = the underlying field for this elliptic curve * @mp *a, *b@ = the coefficients for this curve * - * Returns: A pointer to the curve. + * Returns: A pointer to the curve, or null. * * Use: Creates a curve structure for an elliptic curve defined over * a binary field. The @binproj@ variant uses projective @@ -448,6 +538,111 @@ extern ec_curve *ec_primeproj(field */*f*/, mp */*a*/, mp */*b*/); extern ec_curve *ec_bin(field */*f*/, mp */*a*/, mp */*b*/); extern ec_curve *ec_binproj(field */*f*/, mp */*a*/, mp */*b*/); +/*----- Curve parameter sets ----------------------------------------------*/ + +/* --- @ec_curveparse@ --- * + * + * Arguments: @qd_parse *qd@ = parser context + * + * Returns: Elliptic curve pointer if OK, or null. + * + * Use: Parses an elliptic curve description, which has the form + * + * * a field description + * * an optional `/' + * * `prime', `primeproj', `bin', or `binproj' + * * an optional `:' + * * the %$a$% parameter + * * an optional `,' + * * the %$b$% parameter + */ + +extern ec_curve *ec_curveparse(qd_parse */*qd*/); + +/* --- @ec_ptparse@ --- * + * + * Arguments: @qd_parse *qd@ = parser context + * @ec *p@ = where to put the point + * + * Returns: The point address, or null. + * + * Use: Parses an elliptic curve point. This has the form + * + * * %$x$%-coordinate + * * optional `,' + * * %$y$%-coordinate + */ + +extern ec *ec_ptparse(qd_parse */*qd*/, ec */*p*/); + +/* --- @ec_infoparse@ --- * + * + * Arguments: @qd_parse *qd@ = parser context + * @ec_info *ei@ = curve information block, currently + * uninitialized + * + * Returns: Zero on success, nonzero on failure. + * + * Use: Parses an elliptic curve information string, and stores the + * information in @ei@. This has the form + * + * * elliptic curve description + * * optional `/' + * * common point + * * optional `:' + * * group order + * * optional `*' + * * cofactor + */ + +extern int ec_infoparse(qd_parse */*qd*/, ec_info */*ei*/); + +/* --- @ec_getinfo@ --- * + * + * Arguments: @ec_info *ei@ = where to write the information + * @const char *p@ = string describing a curve + * + * Returns: Null on success, or a pointer to an error message. + * + * Use: Parses out information about a curve. The string is either a + * standard curve name, or a curve info string. + */ + +extern const char *ec_getinfo(ec_info */*ei*/, const char */*p*/); + +/* --- @ec_sameinfop@ --- * + * + * Arguments: @ec_info *ei, *ej@ = two elliptic curve parameter sets + * + * Returns: Nonzero if the curves are identical (not just isomorphic). + * + * Use: Checks for sameness of curve parameters. + */ + +extern int ec_sameinfop(ec_info */*ei*/, ec_info */*ej*/); + +/* --- @ec_freeinfo@ --- * + * + * Arguments: @ec_info *ei@ = elliptic curve information block to free + * + * Returns: --- + * + * Use: Frees the information block. + */ + +extern void ec_freeinfo(ec_info */*ei*/); + +/* --- @ec_checkinfo@ --- * + * + * Arguments: @const ec_info *ei@ = elliptic curve information block + * + * Returns: Null if OK, or pointer to error message. + * + * Use: Checks an elliptic curve according to the rules in SEC1. + */ + +extern const char *ec_checkinfo(const ec_info */*ei*/, grand */*gr*/); + /*----- That's all, folks -------------------------------------------------*/ #ifdef __cplusplus