/* ====================================================================
 * Copyright (c) 2007 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
 *    openssl-core@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.
 *
 */

/*
 * This is a FIPS approved AES PRNG based on ANSI X9.31 A.2.4.
 */

#include "e_os.h"

/*
 * If we don't define _XOPEN_SOURCE_EXTENDED, struct timeval won't be defined
 * and gettimeofday() won't be declared with strict compilers like DEC C in
 * ANSI C mode.
 */
#ifndef _XOPEN_SOURCE_EXTENDED
# define _XOPEN_SOURCE_EXTENDED 1
#endif

#include <openssl/rand.h>
#include <openssl/aes.h>
#include <openssl/err.h>
#include <openssl/fips_rand.h>
#ifndef OPENSSL_SYS_WIN32
# include <sys/time.h>
#endif
#include <assert.h>
#ifndef OPENSSL_SYS_WIN32
# ifdef OPENSSL_UNISTD
#  include OPENSSL_UNISTD
# else
#  include <unistd.h>
# endif
#endif
#include <string.h>
#include <openssl/fips.h>
#include "fips_locl.h"

#ifdef OPENSSL_FIPS

void *OPENSSL_stderr(void);

# define AES_BLOCK_LENGTH        16

/* AES FIPS PRNG implementation */

typedef struct {
    int seeded;
    int keyed;
    int test_mode;
    int second;
    int error;
    unsigned long counter;
    AES_KEY ks;
    int vpos;
    /* Temporary storage for key if it equals seed length */
    unsigned char tmp_key[AES_BLOCK_LENGTH];
    unsigned char V[AES_BLOCK_LENGTH];
    unsigned char DT[AES_BLOCK_LENGTH];
    unsigned char last[AES_BLOCK_LENGTH];
} FIPS_PRNG_CTX;

static FIPS_PRNG_CTX sctx;

static int fips_prng_fail = 0;

void FIPS_rng_stick(void)
{
    fips_prng_fail = 1;
}

static void fips_rand_prng_reset(FIPS_PRNG_CTX * ctx)
{
    ctx->seeded = 0;
    ctx->keyed = 0;
    ctx->test_mode = 0;
    ctx->counter = 0;
    ctx->second = 0;
    ctx->error = 0;
    ctx->vpos = 0;
    OPENSSL_cleanse(ctx->V, AES_BLOCK_LENGTH);
    OPENSSL_cleanse(&ctx->ks, sizeof(AES_KEY));
}

static int fips_set_prng_key(FIPS_PRNG_CTX * ctx,
                             const unsigned char *key,
                             FIPS_RAND_SIZE_T keylen)
{
    FIPS_selftest_check();
    if (keylen != 16 && keylen != 24 && keylen != 32) {
        /* error: invalid key size */
        return 0;
    }
    AES_set_encrypt_key(key, keylen << 3, &ctx->ks);
    if (keylen == 16) {
        memcpy(ctx->tmp_key, key, 16);
        ctx->keyed = 2;
    } else
        ctx->keyed = 1;
    ctx->seeded = 0;
    ctx->second = 0;
    return 1;
}

static int fips_set_prng_seed(FIPS_PRNG_CTX * ctx,
                              const unsigned char *seed,
                              FIPS_RAND_SIZE_T seedlen)
{
    int i;
    if (!ctx->keyed)
        return 0;
    /* In test mode seed is just supplied data */
    if (ctx->test_mode) {
        if (seedlen != AES_BLOCK_LENGTH)
            return 0;
        memcpy(ctx->V, seed, AES_BLOCK_LENGTH);
        ctx->seeded = 1;
        return 1;
    }
    /* Outside test mode XOR supplied data with existing seed */
    for (i = 0; i < seedlen; i++) {
        ctx->V[ctx->vpos++] ^= seed[i];
        if (ctx->vpos == AES_BLOCK_LENGTH) {
            ctx->vpos = 0;
            /*
             * Special case if first seed and key length equals block size
             * check key and seed do not match.
             */
            if (ctx->keyed == 2) {
                if (!memcmp(ctx->tmp_key, ctx->V, 16)) {
                    RANDerr(RAND_F_FIPS_SET_PRNG_SEED,
                            RAND_R_PRNG_SEED_MUST_NOT_MATCH_KEY);
                    return 0;
                }
                OPENSSL_cleanse(ctx->tmp_key, 16);
                ctx->keyed = 1;
            }
            ctx->seeded = 1;
        }
    }
    return 1;
}

static int fips_set_test_mode(FIPS_PRNG_CTX * ctx)
{
    if (ctx->keyed) {
        RANDerr(RAND_F_FIPS_SET_TEST_MODE, RAND_R_PRNG_KEYED);
        return 0;
    }
    ctx->test_mode = 1;
    return 1;
}

int FIPS_rand_test_mode(void)
{
    return fips_set_test_mode(&sctx);
}

int FIPS_rand_set_dt(unsigned char *dt)
{
    if (!sctx.test_mode) {
        RANDerr(RAND_F_FIPS_RAND_SET_DT, RAND_R_NOT_IN_TEST_MODE);
        return 0;
    }
    memcpy(sctx.DT, dt, AES_BLOCK_LENGTH);
    return 1;
}

static void fips_get_dt(FIPS_PRNG_CTX * ctx)
{
# ifdef OPENSSL_SYS_WIN32
    FILETIME ft;
# else
    struct timeval tv;
# endif
    unsigned char *buf = ctx->DT;

# ifndef GETPID_IS_MEANINGLESS
    unsigned long pid;
# endif

# ifdef OPENSSL_SYS_WIN32
    GetSystemTimeAsFileTime(&ft);
    buf[0] = (unsigned char)(ft.dwHighDateTime & 0xff);
    buf[1] = (unsigned char)((ft.dwHighDateTime >> 8) & 0xff);
    buf[2] = (unsigned char)((ft.dwHighDateTime >> 16) & 0xff);
    buf[3] = (unsigned char)((ft.dwHighDateTime >> 24) & 0xff);
    buf[4] = (unsigned char)(ft.dwLowDateTime & 0xff);
    buf[5] = (unsigned char)((ft.dwLowDateTime >> 8) & 0xff);
    buf[6] = (unsigned char)((ft.dwLowDateTime >> 16) & 0xff);
    buf[7] = (unsigned char)((ft.dwLowDateTime >> 24) & 0xff);
# else
    gettimeofday(&tv, NULL);
    buf[0] = (unsigned char)(tv.tv_sec & 0xff);
    buf[1] = (unsigned char)((tv.tv_sec >> 8) & 0xff);
    buf[2] = (unsigned char)((tv.tv_sec >> 16) & 0xff);
    buf[3] = (unsigned char)((tv.tv_sec >> 24) & 0xff);
    buf[4] = (unsigned char)(tv.tv_usec & 0xff);
    buf[5] = (unsigned char)((tv.tv_usec >> 8) & 0xff);
    buf[6] = (unsigned char)((tv.tv_usec >> 16) & 0xff);
    buf[7] = (unsigned char)((tv.tv_usec >> 24) & 0xff);
# endif
    buf[8] = (unsigned char)(ctx->counter & 0xff);
    buf[9] = (unsigned char)((ctx->counter >> 8) & 0xff);
    buf[10] = (unsigned char)((ctx->counter >> 16) & 0xff);
    buf[11] = (unsigned char)((ctx->counter >> 24) & 0xff);

    ctx->counter++;

# ifndef GETPID_IS_MEANINGLESS
    pid = (unsigned long)getpid();
    buf[12] = (unsigned char)(pid & 0xff);
    buf[13] = (unsigned char)((pid >> 8) & 0xff);
    buf[14] = (unsigned char)((pid >> 16) & 0xff);
    buf[15] = (unsigned char)((pid >> 24) & 0xff);
# endif
}

static int fips_rand(FIPS_PRNG_CTX * ctx,
                     unsigned char *out, FIPS_RAND_SIZE_T outlen)
{
    unsigned char R[AES_BLOCK_LENGTH], I[AES_BLOCK_LENGTH];
    unsigned char tmp[AES_BLOCK_LENGTH];
    int i;
    if (ctx->error) {
        RANDerr(RAND_F_FIPS_RAND, RAND_R_PRNG_ERROR);
        return 0;
    }
    if (!ctx->keyed) {
        RANDerr(RAND_F_FIPS_RAND, RAND_R_NO_KEY_SET);
        return 0;
    }
    if (!ctx->seeded) {
        RANDerr(RAND_F_FIPS_RAND, RAND_R_PRNG_NOT_SEEDED);
        return 0;
    }
    for (;;) {
        if (!ctx->test_mode)
            fips_get_dt(ctx);
        AES_encrypt(ctx->DT, I, &ctx->ks);
        for (i = 0; i < AES_BLOCK_LENGTH; i++)
            tmp[i] = I[i] ^ ctx->V[i];
        AES_encrypt(tmp, R, &ctx->ks);
        for (i = 0; i < AES_BLOCK_LENGTH; i++)
            tmp[i] = R[i] ^ I[i];
        AES_encrypt(tmp, ctx->V, &ctx->ks);
        /* Continuous PRNG test */
        if (ctx->second) {
            if (fips_prng_fail)
                memcpy(ctx->last, R, AES_BLOCK_LENGTH);
            if (!memcmp(R, ctx->last, AES_BLOCK_LENGTH)) {
                RANDerr(RAND_F_FIPS_RAND, RAND_R_PRNG_STUCK);
                ctx->error = 1;
                fips_set_selftest_fail();
                return 0;
            }
        }
        memcpy(ctx->last, R, AES_BLOCK_LENGTH);
        if (!ctx->second) {
            ctx->second = 1;
            if (!ctx->test_mode)
                continue;
        }

        if (outlen <= AES_BLOCK_LENGTH) {
            memcpy(out, R, outlen);
            break;
        }

        memcpy(out, R, AES_BLOCK_LENGTH);
        out += AES_BLOCK_LENGTH;
        outlen -= AES_BLOCK_LENGTH;
    }
    return 1;
}

int FIPS_rand_set_key(const unsigned char *key, FIPS_RAND_SIZE_T keylen)
{
    int ret;
    CRYPTO_w_lock(CRYPTO_LOCK_RAND);
    ret = fips_set_prng_key(&sctx, key, keylen);
    CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
    return ret;
}

int FIPS_rand_seed(const void *seed, FIPS_RAND_SIZE_T seedlen)
{
    int ret;
    CRYPTO_w_lock(CRYPTO_LOCK_RAND);
    ret = fips_set_prng_seed(&sctx, seed, seedlen);
    CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
    return ret;
}

int FIPS_rand_bytes(unsigned char *out, FIPS_RAND_SIZE_T count)
{
    int ret;
    CRYPTO_w_lock(CRYPTO_LOCK_RAND);
    ret = fips_rand(&sctx, out, count);
    CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
    return ret;
}

int FIPS_rand_status(void)
{
    int ret;
    CRYPTO_r_lock(CRYPTO_LOCK_RAND);
    ret = sctx.seeded;
    CRYPTO_r_unlock(CRYPTO_LOCK_RAND);
    return ret;
}

void FIPS_rand_reset(void)
{
    CRYPTO_w_lock(CRYPTO_LOCK_RAND);
    fips_rand_prng_reset(&sctx);
    CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
}

static void fips_do_rand_seed(const void *seed, FIPS_RAND_SIZE_T seedlen)
{
    FIPS_rand_seed(seed, seedlen);
}

static void fips_do_rand_add(const void *seed, FIPS_RAND_SIZE_T seedlen,
                             double add_entropy)
{
    FIPS_rand_seed(seed, seedlen);
}

static const RAND_METHOD rand_fips_meth = {
    fips_do_rand_seed,
    FIPS_rand_bytes,
    FIPS_rand_reset,
    fips_do_rand_add,
    FIPS_rand_bytes,
    FIPS_rand_status
};

const RAND_METHOD *FIPS_rand_method(void)
{
    return &rand_fips_meth;
}

#endif
