/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://opensource.org/licenses/CDDL-1.0.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2013 Saso Kiselkov.  All rights reserved.
 * Use is subject to license terms.
 */
#include <sys/edonr.h>

#define EDONR_MODE              512
#define EDONR_BLOCK_SIZE        EdonR512_BLOCK_SIZE

/*
 * Native zio_checksum interface for the Edon-R hash function.
 */
/*ARGSUSED*/
static void
zio_checksum_edonr_native(const void *buf, uint64_t size,
    const void *ctx_template, zio_cksum_t *zcp)
{
        uint8_t         digest[EDONR_MODE / 8];
        EdonRState      ctx;

        ASSERT(ctx_template != NULL);
        bcopy(ctx_template, &ctx, sizeof (ctx));
        EdonRUpdate(&ctx, buf, size * 8);
        EdonRFinal(&ctx, digest);
        bcopy(digest, zcp->zc_word, sizeof (zcp->zc_word));
}

/*
 * Byteswapped zio_checksum interface for the Edon-R hash function.
 */
static void
zio_checksum_edonr_byteswap(const void *buf, uint64_t size,
    const void *ctx_template, zio_cksum_t *zcp)
{
        zio_cksum_t     tmp;

        zio_checksum_edonr_native(buf, size, ctx_template, &tmp);
        zcp->zc_word[0] = BSWAP_64(zcp->zc_word[0]);
        zcp->zc_word[1] = BSWAP_64(zcp->zc_word[1]);
        zcp->zc_word[2] = BSWAP_64(zcp->zc_word[2]);
        zcp->zc_word[3] = BSWAP_64(zcp->zc_word[3]);
}

static void *
zio_checksum_edonr_tmpl_init(const zio_cksum_salt_t *salt)
{
        EdonRState      *ctx;
        uint8_t         salt_block[EDONR_BLOCK_SIZE];

        /*
         * Edon-R needs all but the last hash invocation to be on full-size
         * blocks, but the salt is too small. Rather than simply padding it
         * with zeros, we expand the salt into a new salt block of proper
         * size by double-hashing it (the new salt block will be composed of
         * H(salt) || H(H(salt))).
         */
        EdonRHash(EDONR_MODE, salt->zcs_bytes, sizeof (salt->zcs_bytes) * 8,
            salt_block);
        EdonRHash(EDONR_MODE, salt_block, EDONR_MODE, salt_block +
            EDONR_MODE / 8);

        /*
         * Feed the new salt block into the hash function - this will serve
         * as our MAC key.
         */
        ctx = malloc(sizeof (*ctx));
        bzero(ctx, sizeof (*ctx));
        EdonRInit(ctx, EDONR_MODE);
        EdonRUpdate(ctx, salt_block, sizeof (salt_block) * 8);
        return (ctx);
}

static void
zio_checksum_edonr_tmpl_free(void *ctx_template)
{
        EdonRState      *ctx = ctx_template;

        bzero(ctx, sizeof (*ctx));
        free(ctx);
}