/*
 * Copyright (C) 2011-2012 Free Software Foundation, Inc.
 *
 * Author: Nikos Mavrogiannopoulos
 *
 * This file is part of GnuTLS.
 *
 * The GnuTLS is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>
 *
 */

/*
 * The following code is an implementation of the AES-128-GCM cipher
 */

#include "errors.h"
#include "gnutls_int.h"

#ifdef HAVE_LIBNETTLE

#include <gnutls/crypto.h>
#include "errors.h"
#include <aes-x86.h>
#include <x86-common.h>
#include <byteswap.h>
#include <nettle/gcm.h>
#include <aes-padlock.h>

#define GCM_BLOCK_SIZE 16

/* GCM mode 
 * Actually padlock doesn't include GCM mode. We just use
 * the ECB part of padlock and nettle for everything else.
 */
struct gcm_padlock_aes_ctx {
	struct GCM_CTX(struct padlock_ctx) inner;
	size_t rekey_counter;
};

static void padlock_aes_encrypt(const void *_ctx,
				size_t length, uint8_t * dst,
				const uint8_t * src)
{
	struct padlock_ctx *ctx = (void*)_ctx;
	struct padlock_cipher_data *pce;

	pce = ALIGN16(&ctx->expanded_key);

	if (length > 0)
		padlock_ecb_encrypt(dst, src, pce, length);
}

static void padlock_aes128_set_encrypt_key(struct padlock_ctx *_ctx,
					const uint8_t * key)
{
	struct padlock_ctx *ctx = _ctx;
	ctx->enc = 1;

	padlock_aes_cipher_setkey(_ctx, key, 16);
}

static void padlock_aes256_set_encrypt_key(struct padlock_ctx *_ctx,
					const uint8_t * key)
{
	struct padlock_ctx *ctx = _ctx;
	ctx->enc = 1;

	padlock_aes_cipher_setkey(_ctx, key, 32);
}

static void aes_gcm_deinit(void *_ctx)
{
	struct gcm_padlock_aes_ctx *ctx = _ctx;

	zeroize_temp_key(ctx, sizeof(*ctx));
	gnutls_free(ctx);
}

static int
aes_gcm_cipher_init(gnutls_cipher_algorithm_t algorithm, void **_ctx,
		    int enc)
{
	/* we use key size to distinguish */
	if (algorithm != GNUTLS_CIPHER_AES_128_GCM &&
	    algorithm != GNUTLS_CIPHER_AES_256_GCM)
		return GNUTLS_E_INVALID_REQUEST;

	*_ctx = gnutls_calloc(1, sizeof(struct gcm_padlock_aes_ctx));
	if (*_ctx == NULL) {
		gnutls_assert();
		return GNUTLS_E_MEMORY_ERROR;
	}

	return 0;
}

static int
aes_gcm_cipher_setkey(void *_ctx, const void *key, size_t keysize)
{
	struct gcm_padlock_aes_ctx *ctx = _ctx;

	if (keysize == 16) {
		GCM_SET_KEY(&ctx->inner, padlock_aes128_set_encrypt_key, padlock_aes_encrypt,
			    key);
	} else if (keysize == 32) {
		GCM_SET_KEY(&ctx->inner, padlock_aes256_set_encrypt_key, padlock_aes_encrypt,
			    key);
	} else
		return GNUTLS_E_INVALID_REQUEST;

	ctx->rekey_counter = 0;
	return 0;
}

static int aes_gcm_setiv(void *_ctx, const void *iv, size_t iv_size)
{
	struct gcm_padlock_aes_ctx *ctx = _ctx;

	if (iv_size != GCM_BLOCK_SIZE - 4)
		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	GCM_SET_IV(&ctx->inner, iv_size, iv);

	ctx->rekey_counter = 0;
	return 0;
}

static int
aes_gcm_encrypt(void *_ctx, const void *src, size_t src_size,
		void *dst, size_t length)
{
	struct gcm_padlock_aes_ctx *ctx = _ctx;
	int ret;

	if (unlikely(length < src_size))
		return gnutls_assert_val(GNUTLS_E_SHORT_MEMORY_BUFFER);

	ret = record_aes_gcm_encrypt_size(&ctx->rekey_counter, src_size);
	if (ret < 0) {
		return gnutls_assert_val(ret);
	}

	GCM_ENCRYPT(&ctx->inner, padlock_aes_encrypt, src_size, dst, src);

	return 0;
}

static int
aes_gcm_decrypt(void *_ctx, const void *src, size_t src_size,
		void *dst, size_t dst_size)
{
	struct gcm_padlock_aes_ctx *ctx = _ctx;

	if (unlikely(dst_size < src_size))
		return gnutls_assert_val(GNUTLS_E_SHORT_MEMORY_BUFFER);

	GCM_DECRYPT(&ctx->inner, padlock_aes_encrypt, src_size, dst, src);
	return 0;
}

static int aes_gcm_auth(void *_ctx, const void *src, size_t src_size)
{
	struct gcm_padlock_aes_ctx *ctx = _ctx;

	GCM_UPDATE(&ctx->inner, src_size, src);

	return 0;
}

static void aes_gcm_tag(void *_ctx, void *tag, size_t tagsize)
{
	struct gcm_padlock_aes_ctx *ctx = _ctx;

	GCM_DIGEST(&ctx->inner, padlock_aes_encrypt, tagsize, tag);
}

#include "aes-gcm-aead.h"

const gnutls_crypto_cipher_st _gnutls_aes_gcm_padlock = {
	.init = aes_gcm_cipher_init,
	.setkey = aes_gcm_cipher_setkey,
	.setiv = aes_gcm_setiv,
	.encrypt = aes_gcm_encrypt,
	.decrypt = aes_gcm_decrypt,
	.aead_encrypt = aes_gcm_aead_encrypt,
	.aead_decrypt = aes_gcm_aead_decrypt,
	.deinit = aes_gcm_deinit,
	.tag = aes_gcm_tag,
	.auth = aes_gcm_auth,
};

#endif