/*
 * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (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/crypto.h>
#include <openssl/lhash.h>
#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <openssl/rand.h>
#ifndef OPENSSL_NO_ENGINE
#include <openssl/engine.h>
#endif

int RSA_size(const RSA *r)
{
    return (BN_num_bytes(r->n));
}

int RSA_public_encrypt(int flen, const uint8_t *from, uint8_t *to,
                       RSA *rsa, int padding)
{
    return (rsa->meth->rsa_pub_enc(flen, from, to, rsa, padding));
}

int RSA_private_encrypt(int flen, const uint8_t *from, uint8_t *to,
                        RSA *rsa, int padding)
{
    return (rsa->meth->rsa_priv_enc(flen, from, to, rsa, padding));
}

int RSA_private_decrypt(int flen, const uint8_t *from, uint8_t *to,
                        RSA *rsa, int padding)
{
    return (rsa->meth->rsa_priv_dec(flen, from, to, rsa, padding));
}

int RSA_public_decrypt(int flen, const uint8_t *from, uint8_t *to,
                       RSA *rsa, int padding)
{
    return (rsa->meth->rsa_pub_dec(flen, from, to, rsa, padding));
}

int RSA_flags(const RSA *r)
{
    return ((r == NULL) ? 0 : r->meth->flags);
}

void RSA_blinding_off(RSA *rsa)
{
    BN_BLINDING_free(rsa->blinding);
    rsa->blinding = NULL;
    rsa->flags &= ~RSA_FLAG_BLINDING;
    rsa->flags |= RSA_FLAG_NO_BLINDING;
}

int RSA_blinding_on(RSA *rsa, BN_CTX *ctx)
{
    int ret = 0;

    if (rsa->blinding != NULL)
        RSA_blinding_off(rsa);

    rsa->blinding = RSA_setup_blinding(rsa, ctx);
    if (rsa->blinding == NULL)
        goto err;

    rsa->flags |= RSA_FLAG_BLINDING;
    rsa->flags &= ~RSA_FLAG_NO_BLINDING;
    ret = 1;
err:
    return (ret);
}

static BIGNUM *rsa_get_public_exp(const BIGNUM *d, const BIGNUM *p,
                                  const BIGNUM *q, BN_CTX *ctx)
{
    BIGNUM *ret = NULL, *r0, *r1, *r2;

    if (d == NULL || p == NULL || q == NULL)
        return NULL;

    BN_CTX_start(ctx);
    r0 = BN_CTX_get(ctx);
    r1 = BN_CTX_get(ctx);
    r2 = BN_CTX_get(ctx);
    if (r2 == NULL)
        goto err;

    if (!BN_sub(r1, p, BN_value_one()))
        goto err;
    if (!BN_sub(r2, q, BN_value_one()))
        goto err;
    if (!BN_mul(r0, r1, r2, ctx))
        goto err;

    ret = BN_mod_inverse(NULL, d, r0, ctx);
err:
    BN_CTX_end(ctx);
    return ret;
}

BN_BLINDING *RSA_setup_blinding(RSA *rsa, BN_CTX *in_ctx)
{
    BIGNUM local_n;
    BIGNUM *e, *n;
    BN_CTX *ctx;
    BN_BLINDING *ret = NULL;

    if (in_ctx == NULL) {
        if ((ctx = BN_CTX_new()) == NULL)
            return 0;
    } else
        ctx = in_ctx;

    BN_CTX_start(ctx);
    e = BN_CTX_get(ctx);
    if (e == NULL) {
        RSAerr(RSA_F_RSA_SETUP_BLINDING, ERR_R_MALLOC_FAILURE);
        goto err;
    }

    if (rsa->e == NULL) {
        e = rsa_get_public_exp(rsa->d, rsa->p, rsa->q, ctx);
        if (e == NULL) {
            RSAerr(RSA_F_RSA_SETUP_BLINDING, RSA_R_NO_PUBLIC_EXPONENT);
            goto err;
        }
    } else
        e = rsa->e;

    if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
        /* Set BN_FLG_CONSTTIME flag */
        n = &local_n;
        BN_with_flags(n, rsa->n, BN_FLG_CONSTTIME);
    } else
        n = rsa->n;

    ret = BN_BLINDING_create_param(NULL, e, n, ctx,
                                   rsa->meth->bn_mod_exp, rsa->_method_mod_n);
    if (ret == NULL) {
        RSAerr(RSA_F_RSA_SETUP_BLINDING, ERR_R_BN_LIB);
        goto err;
    }

    BN_BLINDING_set_current_thread(ret);

err:
    BN_CTX_end(ctx);
    if (in_ctx == NULL)
        BN_CTX_free(ctx);
    if (rsa->e == NULL)
        BN_free(e);

    return ret;
}
