/*

 * Copyright 2017-2020 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include <string.h>

#include "internal/sha3.h"

void SHA3_squeeze(uint64_t A[5][5], unsigned char *out, size_t len, size_t r);

void ossl_sha3_reset(KECCAK1600_CTX *ctx)

{

    memset(ctx->A, 0, sizeof(ctx->A));

    ctx->bufsz = 0;

}

int ossl_sha3_init(KECCAK1600_CTX *ctx, unsigned char pad, size_t bitlen)

{

    size_t bsz = SHA3_BLOCKSIZE(bitlen);

    if (bsz <= sizeof(ctx->buf)) {

        ossl_sha3_reset(ctx);

        ctx->block_size = bsz;

        ctx->md_size = bitlen / 8;

        ctx->pad = pad;

        return 1;

    }

    return 0;

}

int ossl_keccak_kmac_init(KECCAK1600_CTX *ctx, unsigned char pad, size_t bitlen)

{

    int ret = ossl_sha3_init(ctx, pad, bitlen);

    if (ret)

        ctx->md_size *= 2;

    return ret;

}

int ossl_sha3_update(KECCAK1600_CTX *ctx, const void *_inp, size_t len)

{

    const unsigned char *inp = _inp;

    size_t bsz = ctx->block_size;

    size_t num, rem;

    if (len == 0)

        return 1;

    if ((num = ctx->bufsz) != 0) {      /* process intermediate buffer? */

        rem = bsz - num;

        if (len < rem) {

            memcpy(ctx->buf + num, inp, len);

            ctx->bufsz += len;

            return 1;

        }

        /*

         * We have enough data to fill or overflow the intermediate

         * buffer. So we append |rem| bytes and process the block,

         * leaving the rest for later processing...

         */

        memcpy(ctx->buf + num, inp, rem);

        inp += rem, len -= rem;

        (void)SHA3_absorb(ctx->A, ctx->buf, bsz, bsz);

        ctx->bufsz = 0;

        /* ctx->buf is processed, ctx->num is guaranteed to be zero */

    }

    if (len >= bsz)

        rem = SHA3_absorb(ctx->A, inp, len, bsz);

    else

        rem = len;

    if (rem) {

        memcpy(ctx->buf, inp + len - rem, rem);

        ctx->bufsz = rem;

    }

    return 1;

}

int ossl_sha3_final(unsigned char *md, KECCAK1600_CTX *ctx)

{

    size_t bsz = ctx->block_size;

    size_t num = ctx->bufsz;

    if (ctx->md_size == 0)

        return 1;

    /*

     * Pad the data with 10*1. Note that |num| can be |bsz - 1|

     * in which case both byte operations below are performed on

     * same byte...

     */

    memset(ctx->buf + num, 0, bsz - num);

    ctx->buf[num] = ctx->pad;

    ctx->buf[bsz - 1] |= 0x80;

    (void)SHA3_absorb(ctx->A, ctx->buf, bsz, bsz);

    SHA3_squeeze(ctx->A, md, ctx->md_size, bsz);

    return 1;

}