/* 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;

}