/*
 * Copyright (c) 2014 - 2021 The GmSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the GmSSL Project.
 *    (http://gmssl.org/)"
 *
 * 4. The name "GmSSL Project" must not be used to endorse or promote
 *    products derived from this software without prior written
 *    permission. For written permission, please contact
 *    guanzhi1980@gmail.com.
 *
 * 5. Products derived from this software may not be called "GmSSL"
 *    nor may "GmSSL" appear in their names without prior written
 *    permission of the GmSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the GmSSL Project
 *    (http://gmssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE GmSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED 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 THE GmSSL PROJECT OR
 * ITS CONTRIBUTORS 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 <string.h>
#include <gmssl/sm3.h>
#include <gmssl/endian.h>
#include <gmssl/error.h>


void sm3_kdf_init(SM3_KDF_CTX *ctx, size_t outlen)
{
	sm3_init(&ctx->sm3_ctx);
	ctx->outlen = outlen;
}

void sm3_kdf_update(SM3_KDF_CTX *ctx, const uint8_t *data, size_t datalen)
{
	sm3_update(&ctx->sm3_ctx, data, datalen);
}

void sm3_kdf_finish(SM3_KDF_CTX *ctx, uint8_t *out)
{
	SM3_CTX sm3_ctx;
	size_t outlen = ctx->outlen;
	uint8_t counter_be[4];
	uint8_t dgst[SM3_DIGEST_SIZE];
	uint32_t counter = 1;
	size_t len;

	while (outlen) {
		PUTU32(counter_be, counter);
		counter++;

		sm3_ctx = ctx->sm3_ctx;
		sm3_update(&sm3_ctx, counter_be, sizeof(counter_be));
		sm3_finish(&sm3_ctx, dgst);

		len = outlen < SM3_DIGEST_SIZE ? outlen : SM3_DIGEST_SIZE;
		memcpy(out, dgst, len);
		out += len;
		outlen -= len;
	}

	memset(&sm3_ctx, 0, sizeof(SM3_CTX));
	memset(dgst, 0, sizeof(dgst));
}