/*
 * Copyright (c) 2015, Vsevolod Stakhov
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *	 * Redistributions of source code must retain the above copyright
 *	   notice, this list of conditions and the following disclaimer.
 *	 * Redistributions in binary form must reproduce the above copyright
 *	   notice, this list of conditions and the following disclaimer in the
 *	   documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY AUTHOR ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL AUTHOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "cryptobox.h"
#include "curve25519.h"
#include "platform_config.h"

extern unsigned long cpu_config;

typedef struct curve25519_impl_s {
	unsigned long cpu_flags;
	const char *desc;

	void (*scalarmult) (guint8 *mypublic,
			const guint8 *secret,
			const guint8 *basepoint);
} curve25519_impl_t;

#define CURVE25519_DECLARE(ext) \
    void scalarmult_##ext(guint8 *mypublic, const guint8 *secret, const guint8 *basepoint)

#define CURVE25519_IMPL(cpuflags, desc, ext) \
    {(cpuflags), desc, scalarmult_##ext}

#if defined(__LP64__)

#if defined(HAVE_AVX)
CURVE25519_DECLARE(avx);
#define CURVE25519_AVX CURVE25519_IMPL(CPUID_AVX, "avx", avx)
#endif

#endif

CURVE25519_DECLARE(ref);
#define CURVE25519_REF CURVE25519_IMPL(0, "ref", ref)

#if !defined(__LP64__)
CURVE25519_DECLARE(donna32);
#define CURVE25519_GENERIC CURVE25519_IMPL(0, "donna32", donna32)
#else
CURVE25519_DECLARE(donna64);
#define CURVE25519_GENERIC CURVE25519_IMPL(0, "donna64", donna64)
#endif

static const curve25519_impl_t curve25519_list[] = {
		CURVE25519_GENERIC,
#if defined(CURVE25519_AVX)
		CURVE25519_AVX,
#endif
};

const guchar secA[] = {0x5A, 0xC9, 0x9F, 0x33, 0x63, 0x2E, 0x5A, 0x76, 0x8D,
					   0xE7, 0xE8, 0x1B, 0xF8, 0x54, 0xC2, 0x7C, 0x46, 0xE3,
					   0xFB, 0xF2, 0xAB, 0xBA, 0xCD, 0x29, 0xEC, 0x4A, 0xFF,
					   0x51, 0x73, 0x69, 0xC6, 0x60};
const guchar secB[] = {0x47, 0xDC, 0x3D, 0x21, 0x41, 0x74, 0x82, 0x0E, 0x11,
					   0x54, 0xB4, 0x9B, 0xC6, 0xCD, 0xB2, 0xAB, 0xD4, 0x5E,
					   0xE9, 0x58, 0x17, 0x05, 0x5D, 0x25, 0x5A, 0xA3, 0x58,
					   0x31, 0xB7, 0x0D, 0x32, 0x60};

static const curve25519_impl_t *curve25519_opt = &curve25519_list[0];

static gboolean
curve25519_test_impl (const curve25519_impl_t *impl)
{
	guchar sec_local[32], sec_ref[32],
		pubA[32], pubB[32];

	curve25519_impl_t ref_impl = CURVE25519_REF;

	ref_impl.scalarmult (pubA, secA, curve25519_basepoint);
	ref_impl.scalarmult (pubB, secB, curve25519_basepoint);

	impl->scalarmult (sec_local, secA, pubB);
	ref_impl.scalarmult (sec_ref, secA, pubB);

	if (memcmp (sec_local, sec_ref, sizeof (sec_ref)) != 0) {
		return FALSE;
	}

	impl->scalarmult (sec_local, secB, pubA);
	ref_impl.scalarmult (sec_ref, secB, pubA);

	if (memcmp (sec_local, sec_ref, sizeof (sec_ref)) != 0) {
		return FALSE;
	}

	impl->scalarmult (sec_local, secB, pubA);
	impl->scalarmult (sec_ref, secA, pubB);

	if (memcmp (sec_local, sec_ref, sizeof (sec_ref)) != 0) {
		return FALSE;
	}

	return TRUE;
}

void
curve25519_load (void)
{
	guint i;

	if (cpu_config != 0) {
		for (i = 0; i < G_N_ELEMENTS(curve25519_list); i++) {
			if (curve25519_list[i].cpu_flags & cpu_config) {
				curve25519_opt = &curve25519_list[i];
				break;
			}
		}
	}
	g_assert (curve25519_test_impl (curve25519_opt));
}

int
curve25519 (guchar *mypublic,
		const guchar *secret,
		const guchar *basepoint)
{
	curve25519_opt->scalarmult (mypublic, secret, basepoint);

	return 0;
}