/* fips/rand/fips_drbg_ctr.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.

 * ====================================================================

 */

#include <stdlib.h>

#include <string.h>

#include <openssl/crypto.h>

#include <openssl/fips.h>

#include <openssl/fips_rand.h>

#include "fips_rand_lcl.h"

static void inc_128(DRBG_CTR_CTX * cctx)

{

    int i;

    unsigned char c;

    unsigned char *p = cctx->V + 15;

    for (i = 0; i < 16; i++) {

        c = *p;

        c++;

        *p = c;

        if (c)

            return;

        p--;

    }

}

static void ctr_XOR(DRBG_CTR_CTX * cctx, const unsigned char *in,

                    size_t inlen)

{

    size_t i, n;

    /* Any zero padding will have no effect on the result as we

     * are XORing. So just process however much input we have.

     */

    if (!in || !inlen)

        return;

    if (inlen < cctx->keylen)

        n = inlen;

    else

        n = cctx->keylen;

    for (i = 0; i < n; i++)

        cctx->K[i] ^= in[i];

    if (inlen <= cctx->keylen)

        return;

    n = inlen - cctx->keylen;

    /* Should never happen */

    if (n > 16)

        n = 16;

    for (i = 0; i < 16; i++)

        cctx->V[i] ^= in[i + cctx->keylen];

}

/* Process a complete block using BCC algorithm of SPP 800-90 10.4.3 */

static void ctr_BCC_block(DRBG_CTR_CTX * cctx, unsigned char *out,

                          const unsigned char *in)

{

    int i;

    for (i = 0; i < 16; i++)

        out[i] ^= in[i];

    AES_encrypt(out, out, &cctx->df_ks);

#if 0

    fprintf(stderr, "BCC in+out\n");

    BIO_dump_fp(stderr, in, 16);

    BIO_dump_fp(stderr, out, 16);

#endif

}

/* Handle several BCC operations for as much data as we need for K and X */

static void ctr_BCC_blocks(DRBG_CTR_CTX * cctx, const unsigned char *in)

{

    ctr_BCC_block(cctx, cctx->KX, in);

    ctr_BCC_block(cctx, cctx->KX + 16, in);

    if (cctx->keylen != 16)

        ctr_BCC_block(cctx, cctx->KX + 32, in);

}

/* Initialise BCC blocks: these have the value 0,1,2 in leftmost positions:

 * see 10.4.2 stage 7.

 */

static void ctr_BCC_init(DRBG_CTR_CTX * cctx)

{

    memset(cctx->KX, 0, 48);

    memset(cctx->bltmp, 0, 16);

    ctr_BCC_block(cctx, cctx->KX, cctx->bltmp);

    cctx->bltmp[3] = 1;

    ctr_BCC_block(cctx, cctx->KX + 16, cctx->bltmp);

    if (cctx->keylen != 16) {

        cctx->bltmp[3] = 2;

        ctr_BCC_block(cctx, cctx->KX + 32, cctx->bltmp);

    }

}

/* Process several blocks into BCC algorithm, some possibly partial */

static void ctr_BCC_update(DRBG_CTR_CTX * cctx,

                           const unsigned char *in, size_t inlen)

{

    if (!in || !inlen)

        return;

    /* If we have partial block handle it first */

    if (cctx->bltmp_pos) {

        size_t left = 16 - cctx->bltmp_pos;

        /* If we now have a complete block process it */

        if (inlen >= left) {

            memcpy(cctx->bltmp + cctx->bltmp_pos, in, left);

            ctr_BCC_blocks(cctx, cctx->bltmp);

            cctx->bltmp_pos = 0;

            inlen -= left;

            in += left;

        }

    }

    /* Process zero or more complete blocks */

    while (inlen >= 16) {

        ctr_BCC_blocks(cctx, in);

        in += 16;

        inlen -= 16;

    }

    /* Copy any remaining partial block to the temporary buffer */

    if (inlen > 0) {

        memcpy(cctx->bltmp + cctx->bltmp_pos, in, inlen);

        cctx->bltmp_pos += inlen;

    }

}

static void ctr_BCC_final(DRBG_CTR_CTX * cctx)

{

    if (cctx->bltmp_pos) {

        memset(cctx->bltmp + cctx->bltmp_pos, 0, 16 - cctx->bltmp_pos);

        ctr_BCC_blocks(cctx, cctx->bltmp);

    }

}

static void ctr_df(DRBG_CTR_CTX * cctx,

                   const unsigned char *in1, size_t in1len,

                   const unsigned char *in2, size_t in2len,

                   const unsigned char *in3, size_t in3len)

{

    size_t inlen;

    unsigned char *p = cctx->bltmp;

    static unsigned char c80 = 0x80;

    ctr_BCC_init(cctx);

    if (!in1)

        in1len = 0;

    if (!in2)

        in2len = 0;

    if (!in3)

        in3len = 0;

    inlen = in1len + in2len + in3len;

    /* Initialise L||N in temporary block */

    *p++ = (inlen >> 24) & 0xff;

    *p++ = (inlen >> 16) & 0xff;

    *p++ = (inlen >> 8) & 0xff;

    *p++ = inlen & 0xff;

    /* NB keylen is at most 32 bytes */

    *p++ = 0;

    *p++ = 0;

    *p++ = 0;

    *p = (unsigned char)((cctx->keylen + 16) & 0xff);

    cctx->bltmp_pos = 8;

    ctr_BCC_update(cctx, in1, in1len);

    ctr_BCC_update(cctx, in2, in2len);

    ctr_BCC_update(cctx, in3, in3len);

    ctr_BCC_update(cctx, &c80, 1);

    ctr_BCC_final(cctx);

    /* Set up key K */

    AES_set_encrypt_key(cctx->KX, cctx->keylen * 8, &cctx->df_kxks);

    /* X follows key K */

    AES_encrypt(cctx->KX + cctx->keylen, cctx->KX, &cctx->df_kxks);

    AES_encrypt(cctx->KX, cctx->KX + 16, &cctx->df_kxks);

    if (cctx->keylen != 16)

        AES_encrypt(cctx->KX + 16, cctx->KX + 32, &cctx->df_kxks);

#if 0

    fprintf(stderr, "Output of ctr_df:\n");

    BIO_dump_fp(stderr, cctx->KX, cctx->keylen + 16);

#endif

}

/* NB the no-df  Update in SP800-90 specifies a constant input length

 * of seedlen, however other uses of this algorithm pad the input with

 * zeroes if necessary and have up to two parameters XORed together,

 * handle both cases in this function instead.

 */

static void ctr_Update(DRBG_CTX *dctx,

                       const unsigned char *in1, size_t in1len,

                       const unsigned char *in2, size_t in2len,

                       const unsigned char *nonce, size_t noncelen)

{

    DRBG_CTR_CTX *cctx = &dctx->d.ctr;

    /* ks is already setup for correct key */

    inc_128(cctx);

    AES_encrypt(cctx->V, cctx->K, &cctx->ks);

    /* If keylen longer than 128 bits need extra encrypt */

    if (cctx->keylen != 16) {

        inc_128(cctx);

        AES_encrypt(cctx->V, cctx->K + 16, &cctx->ks);

    }

    inc_128(cctx);

    AES_encrypt(cctx->V, cctx->V, &cctx->ks);

    /* If 192 bit key part of V is on end of K */

    if (cctx->keylen == 24) {

        memcpy(cctx->V + 8, cctx->V, 8);

        memcpy(cctx->V, cctx->K + 24, 8);

    }

    if (dctx->xflags & DRBG_FLAG_CTR_USE_DF) {

        /* If no input reuse existing derived value */

        if (in1 || nonce || in2)

            ctr_df(cctx, in1, in1len, nonce, noncelen, in2, in2len);

        /* If this a reuse input in1len != 0 */

        if (in1len)

            ctr_XOR(cctx, cctx->KX, dctx->seedlen);

    } else {

        ctr_XOR(cctx, in1, in1len);

        ctr_XOR(cctx, in2, in2len);

    }

    AES_set_encrypt_key(cctx->K, dctx->strength, &cctx->ks);

#if 0

    fprintf(stderr, "K+V after update is:\n");

    BIO_dump_fp(stderr, cctx->K, cctx->keylen);

    BIO_dump_fp(stderr, cctx->V, 16);

#endif

}

static int drbg_ctr_instantiate(DRBG_CTX *dctx,

                                const unsigned char *ent, size_t entlen,

                                const unsigned char *nonce, size_t noncelen,

                                const unsigned char *pers, size_t perslen)

{

    DRBG_CTR_CTX *cctx = &dctx->d.ctr;

    memset(cctx->K, 0, sizeof(cctx->K));

    memset(cctx->V, 0, sizeof(cctx->V));

    AES_set_encrypt_key(cctx->K, dctx->strength, &cctx->ks);

    ctr_Update(dctx, ent, entlen, pers, perslen, nonce, noncelen);

    return 1;

}

static int drbg_ctr_reseed(DRBG_CTX *dctx,

                           const unsigned char *ent, size_t entlen,

                           const unsigned char *adin, size_t adinlen)

{

    ctr_Update(dctx, ent, entlen, adin, adinlen, NULL, 0);

    return 1;

}

static int drbg_ctr_generate(DRBG_CTX *dctx,

                             unsigned char *out, size_t outlen,

                             const unsigned char *adin, size_t adinlen)

{

    DRBG_CTR_CTX *cctx = &dctx->d.ctr;

    if (adin && adinlen) {

        ctr_Update(dctx, adin, adinlen, NULL, 0, NULL, 0);

        /* This means we reuse derived value */

        if (dctx->xflags & DRBG_FLAG_CTR_USE_DF) {

            adin = NULL;

            adinlen = 1;

        }

    } else

        adinlen = 0;

    for (;;) {

        inc_128(cctx);

        if (outlen < 16) {

            /* Use K as temp space as it will be updated */

            AES_encrypt(cctx->V, cctx->K, &cctx->ks);

            memcpy(out, cctx->K, outlen);

            break;

        }

        AES_encrypt(cctx->V, out, &cctx->ks);

        out += 16;

        outlen -= 16;

        if (outlen == 0)

            break;

    }

    ctr_Update(dctx, adin, adinlen, NULL, 0, NULL, 0);

    return 1;

}

static int drbg_ctr_uninstantiate(DRBG_CTX *dctx)

{

    memset(&dctx->d.ctr, 0, sizeof(DRBG_CTR_CTX));

    return 1;

}

int fips_drbg_ctr_init(DRBG_CTX *dctx)

{

    DRBG_CTR_CTX *cctx = &dctx->d.ctr;

    size_t keylen;

    switch (dctx->type) {

    case NID_aes_128_ctr:

        keylen = 16;

        break;

    case NID_aes_192_ctr:

        keylen = 24;

        break;

    case NID_aes_256_ctr:

        keylen = 32;

        break;

    default:

        return -2;

    }

    dctx->instantiate = drbg_ctr_instantiate;

    dctx->reseed = drbg_ctr_reseed;

    dctx->generate = drbg_ctr_generate;

    dctx->uninstantiate = drbg_ctr_uninstantiate;

    cctx->keylen = keylen;

    dctx->strength = keylen * 8;

    dctx->blocklength = 16;

    dctx->seedlen = keylen + 16;

    if (dctx->xflags & DRBG_FLAG_CTR_USE_DF) {

        /* df initialisation */

        static unsigned char df_key[32] = {

            0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,

            0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,

            0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,

            0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f

        };

        /* Set key schedule for df_key */

        AES_set_encrypt_key(df_key, dctx->strength, &cctx->df_ks);

        dctx->min_entropy = cctx->keylen;

        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;

    } else {

        dctx->min_entropy = dctx->seedlen;

        dctx->max_entropy = dctx->seedlen;

        /* Nonce not used */

        dctx->min_nonce = 0;

        dctx->max_nonce = 0;

        dctx->max_pers = dctx->seedlen;

        dctx->max_adin = dctx->seedlen;

    }

    dctx->max_request = 1 << 16;

    dctx->reseed_interval = 1 << 24;

    return 1;

}