/* fips/rand/fips_drbg_hash.c */
/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
 * project.
 */
/* ====================================================================
 * Copyright (c) 2011 The OpenSSL 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 OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL 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 OpenSSL 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.
 * ====================================================================
 */

#define OPENSSL_FIPSAPI

#include <stdlib.h>
#include <string.h>
#include <openssl/crypto.h>
#include <openssl/fips.h>
#include "crypto/fips.h"
#include <openssl/fips_rand.h>
#include "fips_rand_lcl.h"

/* This is Hash_df from SP 800-90 10.4.1 */

static int hash_df(DRBG_CTX *dctx, unsigned char *out,
                   const unsigned char *in1, size_t in1len,
                   const unsigned char *in2, size_t in2len,
                   const unsigned char *in3, size_t in3len,
                   const unsigned char *in4, size_t in4len)
{
    EVP_MD_CTX *mctx = dctx->d.hash.mctx;
    unsigned char *vtmp = dctx->d.hash.vtmp;
    unsigned char tmp[6];
    /* Standard only ever needs seedlen bytes which is always less than
     * maximum permitted so no need to check length.
     */
    size_t outlen = dctx->seedlen;
    tmp[0] = 1;
    tmp[1] = ((outlen * 8) >> 24) & 0xff;
    tmp[2] = ((outlen * 8) >> 16) & 0xff;
    tmp[3] = ((outlen * 8) >> 8) & 0xff;
    tmp[4] = (outlen * 8) & 0xff;
    if (!in1) {
        tmp[5] = (unsigned char)in1len;
        in1 = tmp + 5;
        in1len = 1;
    }
    for (;;) {
        if (!FIPS_digestinit(mctx, dctx->d.hash.md))
            return 0;
        if (!FIPS_digestupdate(mctx, tmp, 5))
            return 0;
        if (in1 && !FIPS_digestupdate(mctx, in1, in1len))
            return 0;
        if (in2 && !FIPS_digestupdate(mctx, in2, in2len))
            return 0;
        if (in3 && !FIPS_digestupdate(mctx, in3, in3len))
            return 0;
        if (in4 && !FIPS_digestupdate(mctx, in4, in4len))
            return 0;
        if (outlen < dctx->blocklength) {
            if (!FIPS_digestfinal(mctx, vtmp, NULL))
                return 0;
            memcpy(out, vtmp, outlen);
            OPENSSL_cleanse(vtmp, dctx->blocklength);
            return 1;
        } else if (!FIPS_digestfinal(mctx, out, NULL))
            return 0;

        outlen -= dctx->blocklength;
        if (outlen == 0)
            return 1;
        tmp[0]++;
        out += dctx->blocklength;
    }
}

/* Add an unsigned buffer to the buf value, storing the result in buf. For
 * this algorithm the length of input never exceeds the seed length.
 */

static void ctx_add_buf(DRBG_CTX *dctx, unsigned char *buf,
                        unsigned char *in, size_t inlen)
{
    size_t i = inlen;
    const unsigned char *q;
    unsigned char c, *p;
    p = buf + dctx->seedlen;
    q = in + inlen;

    OPENSSL_assert(i <= dctx->seedlen);

    /* Special case: zero length, just increment buffer */
    if (i)
        c = 0;
    else
        c = 1;

    while (i) {
        int r;
        p--;
        q--;
        r = *p + *q + c;
        /* Carry */
        if (r > 0xff)
            c = 1;
        else
            c = 0;
        *p = r & 0xff;
        i--;
    }

    i = dctx->seedlen - inlen;

    /* If not adding whole buffer handle final carries */
    if (c && i) {
        do {
            p--;
            c = *p;
            c++;
            *p = c;
            if (c)
                return;
        } while (i--);
    }
}

/* Finalise and add hash to V */

static int ctx_add_md(DRBG_CTX *dctx)
{
    if (!FIPS_digestfinal(dctx->d.hash.mctx, dctx->d.hash.vtmp, NULL))
        return 0;
    ctx_add_buf(dctx, dctx->d.hash.V, dctx->d.hash.vtmp, dctx->blocklength);
    return 1;
}

static int hash_gen(DRBG_CTX *dctx, unsigned char *out, size_t outlen)
{
    DRBG_HASH_CTX *hctx = &dctx->d.hash;
    if (outlen == 0)
        return 1;
    memcpy(hctx->vtmp, hctx->V, dctx->seedlen);
    for (;;) {
        FIPS_digestinit(hctx->mctx, hctx->md);
        FIPS_digestupdate(hctx->mctx, hctx->vtmp, dctx->seedlen);
        if (outlen < dctx->blocklength) {
            FIPS_digestfinal(hctx->mctx, hctx->vtmp, NULL);
            memcpy(out, hctx->vtmp, outlen);
            return 1;
        } else {
            FIPS_digestfinal(hctx->mctx, out, NULL);
            outlen -= dctx->blocklength;
            if (outlen == 0)
                return 1;
            out += dctx->blocklength;
        }
        ctx_add_buf(dctx, hctx->vtmp, NULL, 0);
    }
}

static int drbg_hash_instantiate(DRBG_CTX *dctx,
                                 const unsigned char *ent, size_t ent_len,
                                 const unsigned char *nonce, size_t nonce_len,
                                 const unsigned char *pstr, size_t pstr_len)
{
    DRBG_HASH_CTX *hctx = &dctx->d.hash;
    if (!hash_df(dctx, hctx->V,
                 ent, ent_len, nonce, nonce_len, pstr, pstr_len, NULL, 0))
        return 0;
    if (!hash_df(dctx, hctx->C,
                 NULL, 0, hctx->V, dctx->seedlen, NULL, 0, NULL, 0))
        return 0;

#ifdef HASH_DRBG_TRACE
    fprintf(stderr, "V+C after instantiate:\n");
    hexprint(stderr, hctx->V, dctx->seedlen);
    hexprint(stderr, hctx->C, dctx->seedlen);
#endif
    return 1;
}

static int drbg_hash_reseed(DRBG_CTX *dctx,
                            const unsigned char *ent, size_t ent_len,
                            const unsigned char *adin, size_t adin_len)
{
    DRBG_HASH_CTX *hctx = &dctx->d.hash;
    /* V about to be updated so use C as output instead */
    if (!hash_df(dctx, hctx->C,
                 NULL, 1, hctx->V, dctx->seedlen,
                 ent, ent_len, adin, adin_len))
        return 0;
    memcpy(hctx->V, hctx->C, dctx->seedlen);
    if (!hash_df(dctx, hctx->C, NULL, 0,
                 hctx->V, dctx->seedlen, NULL, 0, NULL, 0))
        return 0;
#ifdef HASH_DRBG_TRACE
    fprintf(stderr, "V+C after reseed:\n");
    hexprint(stderr, hctx->V, dctx->seedlen);
    hexprint(stderr, hctx->C, dctx->seedlen);
#endif
    return 1;
}

static int drbg_hash_generate(DRBG_CTX *dctx,
                              unsigned char *out, size_t outlen,
                              const unsigned char *adin, size_t adin_len)
{
    DRBG_HASH_CTX *hctx = &dctx->d.hash;
    EVP_MD_CTX *mctx = hctx->mctx;
    unsigned char tmp[4];
    if (adin && adin_len) {
        tmp[0] = 2;
        if (!FIPS_digestinit(mctx, hctx->md))
            return 0;
        if (!EVP_DigestUpdate(mctx, tmp, 1))
            return 0;
        if (!EVP_DigestUpdate(mctx, hctx->V, dctx->seedlen))
            return 0;
        if (!EVP_DigestUpdate(mctx, adin, adin_len))
            return 0;
        if (!ctx_add_md(dctx))
            return 0;
    }
    if (!hash_gen(dctx, out, outlen))
        return 0;

    tmp[0] = 3;
    if (!FIPS_digestinit(mctx, hctx->md))
        return 0;
    if (!EVP_DigestUpdate(mctx, tmp, 1))
        return 0;
    if (!EVP_DigestUpdate(mctx, hctx->V, dctx->seedlen))
        return 0;

    if (!ctx_add_md(dctx))
        return 0;

    ctx_add_buf(dctx, hctx->V, hctx->C, dctx->seedlen);

    tmp[0] = (dctx->reseed_counter >> 24) & 0xff;
    tmp[1] = (dctx->reseed_counter >> 16) & 0xff;
    tmp[2] = (dctx->reseed_counter >> 8) & 0xff;
    tmp[3] = dctx->reseed_counter & 0xff;
    ctx_add_buf(dctx, hctx->V, tmp, 4);
#ifdef HASH_DRBG_TRACE
    fprintf(stderr, "V+C after generate:\n");
    hexprint(stderr, hctx->V, dctx->seedlen);
    hexprint(stderr, hctx->C, dctx->seedlen);
#endif
    return 1;
}

static int drbg_hash_uninstantiate(DRBG_CTX *dctx)
{
    EVP_MD_CTX_free(dctx->d.hash.mctx);
    OPENSSL_cleanse(&dctx->d.hash, sizeof(DRBG_HASH_CTX));
    return 1;
}

int fips_drbg_hash_init(DRBG_CTX *dctx)
{
    const EVP_MD *md;
    DRBG_HASH_CTX *hctx = &dctx->d.hash;
    md = EVP_get_digestbynid(dctx->type);
    if (!md)
        return -2;
    switch (dctx->type) {
    case NID_sha1:
        dctx->strength = 128;
        break;

    case NID_sha224:
        dctx->strength = 192;
        break;

    default:
        dctx->strength = 256;
        break;
    }

    dctx->instantiate = drbg_hash_instantiate;
    dctx->reseed = drbg_hash_reseed;
    dctx->generate = drbg_hash_generate;
    dctx->uninstantiate = drbg_hash_uninstantiate;

    dctx->d.hash.md = md;
    hctx->mctx = EVP_MD_CTX_new();
    if (hctx->mctx == NULL)
        return -1;

    /* These are taken from SP 800-90 10.1 table 2 */

    dctx->blocklength = EVP_MD_size(md);
    if (dctx->blocklength > 32)
        dctx->seedlen = 111;
    else
        dctx->seedlen = 55;

    dctx->min_entropy = dctx->strength / 8;
    dctx->max_entropy = DRBG_MAX_LENGTH;

    dctx->min_nonce = dctx->min_entropy / 2;
    dctx->max_nonce = DRBG_MAX_LENGTH;

    dctx->max_pers = DRBG_MAX_LENGTH;
    dctx->max_adin = DRBG_MAX_LENGTH;

    dctx->max_request = 1 << 16;
    dctx->reseed_interval = 1 << 24;

    return 1;
}
