/*

 * Copyright 1998-2023 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 <openssl/opensslconf.h>

#include "internal/cryptlib.h"

#include "bn_local.h"

#define BN_BLINDING_COUNTER 32

struct bn_blinding_st {

    BIGNUM *A;

    BIGNUM *Ai;

    BIGNUM *e;

    BIGNUM *mod; /* just a reference */

    CRYPTO_THREAD_ID tid;

    int counter;

    unsigned long flags;

    BN_MONT_CTX *m_ctx;

    int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,

        const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);

    CRYPTO_RWLOCK *lock;

};

BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai, BIGNUM *mod)

{

    BN_BLINDING *ret = NULL;

    bn_check_top(mod);

    if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) {

        ERR_raise(ERR_LIB_BN, ERR_R_MALLOC_FAILURE);

        return NULL;

    }

    ret->lock = CRYPTO_THREAD_lock_new();

    if (ret->lock == NULL) {

        ERR_raise(ERR_LIB_BN, ERR_R_MALLOC_FAILURE);

        OPENSSL_free(ret);

        return NULL;

    }

    BN_BLINDING_set_current_thread(ret);

    if (A != NULL) {

        if ((ret->A = BN_dup(A)) == NULL)

            goto err;

    }

    if (Ai != NULL) {

        if ((ret->Ai = BN_dup(Ai)) == NULL)

            goto err;

    }

    /* save a copy of mod in the BN_BLINDING structure */

    if ((ret->mod = BN_dup(mod)) == NULL)

        goto err;

    if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)

        BN_set_flags(ret->mod, BN_FLG_CONSTTIME);

    /*

     * Set the counter to the special value -1 to indicate that this is

     * never-used fresh blinding that does not need updating before first

     * use.

     */

    ret->counter = -1;

    return ret;

err:

    BN_BLINDING_free(ret);

    return NULL;

}

void BN_BLINDING_free(BN_BLINDING *r)

{

    if (r == NULL)

        return;

    BN_free(r->A);

    BN_free(r->Ai);

    BN_free(r->e);

    BN_free(r->mod);

    CRYPTO_THREAD_lock_free(r->lock);

    OPENSSL_free(r);

}

int BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx)

{

    int ret = 0;

    if ((b->A == NULL) || (b->Ai == NULL)) {

        ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);

        goto err;

    }

    if (b->counter == -1)

        b->counter = 0;

    if (++b->counter == BN_BLINDING_COUNTER && b->e != NULL && !(b->flags & BN_BLINDING_NO_RECREATE)) {

        /* re-create blinding parameters */

        if (!BN_BLINDING_create_param(b, NULL, NULL, ctx, NULL, NULL))

            goto err;

    } else if (!(b->flags & BN_BLINDING_NO_UPDATE)) {

        if (b->m_ctx != NULL) {

            if (!bn_mul_mont_fixed_top(b->Ai, b->Ai, b->Ai, b->m_ctx, ctx)

                || !bn_mul_mont_fixed_top(b->A, b->A, b->A, b->m_ctx, ctx))

                goto err;

        } else {

            if (!BN_mod_mul(b->Ai, b->Ai, b->Ai, b->mod, ctx)

                || !BN_mod_mul(b->A, b->A, b->A, b->mod, ctx))

                goto err;

        }

    }

    ret = 1;

err:

    if (b->counter == BN_BLINDING_COUNTER)

        b->counter = 0;

    return ret;

}

int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)

{

    return BN_BLINDING_convert_ex(n, NULL, b, ctx);

}

int BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)

{

    int ret = 1;

    bn_check_top(n);

    if ((b->A == NULL) || (b->Ai == NULL)) {

        ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);

        return 0;

    }

    if (b->counter == -1)

        /* Fresh blinding, doesn't need updating. */

        b->counter = 0;

    else if (!BN_BLINDING_update(b, ctx))

        return 0;

    if (r != NULL && (BN_copy(r, b->Ai) == NULL))

        return 0;

    if (b->m_ctx != NULL)

        ret = BN_mod_mul_montgomery(n, n, b->A, b->m_ctx, ctx);

    else

        ret = BN_mod_mul(n, n, b->A, b->mod, ctx);

    return ret;

}

int BN_BLINDING_invert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)

{

    return BN_BLINDING_invert_ex(n, NULL, b, ctx);

}

int BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b,

    BN_CTX *ctx)

{

    int ret;

    bn_check_top(n);

    if (r == NULL && (r = b->Ai) == NULL) {

        ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);

        return 0;

    }

    if (b->m_ctx != NULL) {

        /* ensure that BN_mod_mul_montgomery takes pre-defined path */

        if (n->dmax >= r->top) {

            size_t i, rtop = r->top, ntop = n->top;

            BN_ULONG mask;

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

                mask = (BN_ULONG)0 - ((i - ntop) >> (8 * sizeof(i) - 1));

                n->d[i] &= mask;

            }

            mask = (BN_ULONG)0 - ((rtop - ntop) >> (8 * sizeof(ntop) - 1));

            /* always true, if (rtop >= ntop) n->top = r->top; */

            n->top = (int)(rtop & ~mask) | (ntop & mask);

            n->flags |= (BN_FLG_FIXED_TOP & ~mask);

        }

        ret = bn_mul_mont_fixed_top(n, n, r, b->m_ctx, ctx);

        bn_correct_top_consttime(n);

    } else {

        ret = BN_mod_mul(n, n, r, b->mod, ctx);

    }

    bn_check_top(n);

    return ret;

}

int BN_BLINDING_is_current_thread(BN_BLINDING *b)

{

    return CRYPTO_THREAD_compare_id(CRYPTO_THREAD_get_current_id(), b->tid);

}

void BN_BLINDING_set_current_thread(BN_BLINDING *b)

{

    b->tid = CRYPTO_THREAD_get_current_id();

}

int BN_BLINDING_lock(BN_BLINDING *b)

{

    return CRYPTO_THREAD_write_lock(b->lock);

}

int BN_BLINDING_unlock(BN_BLINDING *b)

{

    return CRYPTO_THREAD_unlock(b->lock);

}

unsigned long BN_BLINDING_get_flags(const BN_BLINDING *b)

{

    return b->flags;

}

void BN_BLINDING_set_flags(BN_BLINDING *b, unsigned long flags)

{

    b->flags = flags;

}

BN_BLINDING *BN_BLINDING_create_param(BN_BLINDING *b,

    const BIGNUM *e, BIGNUM *m, BN_CTX *ctx,

    int (*bn_mod_exp)(BIGNUM *r,

        const BIGNUM *a,

        const BIGNUM *p,

        const BIGNUM *m,

        BN_CTX *ctx,

        BN_MONT_CTX *m_ctx),

    BN_MONT_CTX *m_ctx)

{

    int retry_counter = 32;

    BN_BLINDING *ret = NULL;

    if (b == NULL)

        ret = BN_BLINDING_new(NULL, NULL, m);

    else

        ret = b;

    if (ret == NULL)

        goto err;

    if (ret->A == NULL && (ret->A = BN_new()) == NULL)

        goto err;

    if (ret->Ai == NULL && (ret->Ai = BN_new()) == NULL)

        goto err;

    if (e != NULL) {

        BN_free(ret->e);

        ret->e = BN_dup(e);

    }

    if (ret->e == NULL)

        goto err;

    if (bn_mod_exp != NULL)

        ret->bn_mod_exp = bn_mod_exp;

    if (m_ctx != NULL)

        ret->m_ctx = m_ctx;

    do {

        int rv;

        if (!BN_priv_rand_range_ex(ret->A, ret->mod, 0, ctx))

            goto err;

        if (int_bn_mod_inverse(ret->Ai, ret->A, ret->mod, ctx, &rv))

            break;

        /*

         * this should almost never happen for good RSA keys

         */

        if (!rv)

            goto err;

        if (retry_counter-- == 0) {

            ERR_raise(ERR_LIB_BN, BN_R_TOO_MANY_ITERATIONS);

            goto err;

        }

    } while (1);

    if (ret->bn_mod_exp != NULL && ret->m_ctx != NULL) {

        if (!ret->bn_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx, ret->m_ctx))

            goto err;

    } else {

        if (!BN_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx))

            goto err;

    }

    if (ret->m_ctx != NULL) {

        if (!bn_to_mont_fixed_top(ret->Ai, ret->Ai, ret->m_ctx, ctx)

            || !bn_to_mont_fixed_top(ret->A, ret->A, ret->m_ctx, ctx))

            goto err;

    }

    return ret;

err:

    if (b == NULL) {

        BN_BLINDING_free(ret);

        ret = NULL;

    }

    return ret;

}