elliptic_test.c

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/*
 * Copyright (C) 2025 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

/** @file
 *
 * Elliptic curve self-tests
 *
 */

/* Forcibly enable assertions */
#undef NDEBUG

#include <stdint.h>
#include <string.h>
#include <assert.h>
#include <ipxe/bigint.h>
#include <ipxe/crypto.h>
#include <ipxe/test.h>
#include "elliptic_test.h"

/**
 * Report elliptic curve sanity test result
 *
 * @v curve             Elliptic curve
 * @v file              Test code file
 * @v line              Test code line
 */
void elliptic_curve_okx ( struct elliptic_curve *curve, const char *file,
                          unsigned int line ) {
        static const uint8_t one[] = { 1 };
        size_t pointsize = curve->pointsize;
        size_t keysize = curve->keysize;
        uint8_t point[pointsize];
        uint8_t scalar[keysize];
        struct {
                bigint_t ( bigint_required_size ( keysize ) ) scalar;
                bigint_t ( bigint_required_size ( keysize ) ) one;
        } temp;

        /* Check that curve has the required properties */
        okx ( curve->base != NULL, file, line );
        okx ( curve->order != NULL, file, line );

        /* Test multiplying base point by group order.  Result should
         * be the point at infinity, which should not be representable
         * as a point in affine coordinates (and so should fail).
         */
        okx ( elliptic_multiply ( curve, curve->base, curve->order,
                                  point ) != 0, file, line );

        /* Test multiplying base point by group order plus one, to get
         * back to the base point.
         */
        bigint_init ( &temp.scalar, curve->order, keysize );
        bigint_init ( &temp.one, one, sizeof ( one ) );
        bigint_add ( &temp.one, &temp.scalar );
        bigint_done ( &temp.scalar, scalar, sizeof ( scalar ) );
        okx ( elliptic_multiply ( curve, curve->base, scalar, point ) == 0,
              file, line );
        okx ( memcmp ( point, curve->base, pointsize ) == 0, file, line );
}

/**
 * Report elliptic curve point multiplication test result
 *
 * @v test              Elliptic curve point multiplication test
 * @v file              Test code file
 * @v line              Test code line
 */
void elliptic_multiply_okx ( struct elliptic_multiply_test *test,
                             const char *file, unsigned int line ) {
        struct elliptic_curve *curve = test->curve;
        size_t pointsize = curve->pointsize;
        size_t keysize = curve->keysize;
        uint8_t actual[pointsize];
        const void *base;
        int rc;

        /* Sanity checks */
        okx ( ( test->base_len == pointsize ) || ( ! test->base_len ),
              file, line );
        okx ( test->scalar_len == keysize, file, line );
        okx ( ( test->expected_len == pointsize ) || ( ! test->expected_len ),
              file, line );

        /* Perform point multiplication */
        base = ( test->base_len ? test->base : curve->base );
        rc = elliptic_multiply ( curve, base, test->scalar, actual );
        if ( test->expected_len ) {
                okx ( rc == 0, file, line );
        } else {
                okx ( rc != 0, file, line );
        }

        /* Check expected result */
        okx ( memcmp ( actual, test->expected, test->expected_len ) == 0,
              file, line );
}

/**
 * Report elliptic curve point addition test result
 *
 * @v test              Elliptic curve point addition test
 * @v file              Test code file
 * @v line              Test code line
 */
void elliptic_add_okx ( struct elliptic_add_test *test,
                        const char *file, unsigned int line ) {
        struct elliptic_curve *curve = test->curve;
        size_t pointsize = curve->pointsize;
        uint8_t actual[pointsize];
        int rc;

        /* Sanity checks */
        okx ( test->addend_len == pointsize, file, line );
        okx ( test->augend_len == pointsize, file, line );
        okx ( ( test->expected_len == pointsize ) || ( ! test->expected_len ),
              file, line );

        /* Perform point addition */
        rc = elliptic_add ( curve, test->addend, test->augend, actual );
        if ( test->expected_len ) {
                okx ( rc == 0, file, line );
        } else {
                okx ( rc != 0, file, line );
        }

        /* Check expected result */
        okx ( memcmp ( actual, test->expected, test->expected_len ) == 0,
              file, line );
}