/* crypto/rsa/rsa_gen.c */

/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)

 * All rights reserved.

 *

 * This package is an SSL implementation written

 * by Eric Young (eay@cryptsoft.com).

 * The implementation was written so as to conform with Netscapes SSL.

 *

 * This library is free for commercial and non-commercial use as long as

 * the following conditions are aheared to.  The following conditions

 * apply to all code found in this distribution, be it the RC4, RSA,

 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation

 * included with this distribution is covered by the same copyright terms

 * except that the holder is Tim Hudson (tjh@cryptsoft.com).

 *

 * Copyright remains Eric Young's, and as such any Copyright notices in

 * the code are not to be removed.

 * If this package is used in a product, Eric Young should be given attribution

 * as the author of the parts of the library used.

 * This can be in the form of a textual message at program startup or

 * in documentation (online or textual) provided with the package.

 *

 * 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 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 acknowledgement:

 *    "This product includes cryptographic software written by

 *     Eric Young (eay@cryptsoft.com)"

 *    The word 'cryptographic' can be left out if the rouines from the library

 *    being used are not cryptographic related :-).

 * 4. If you include any Windows specific code (or a derivative thereof) from

 *    the apps directory (application code) you must include an acknowledgement:

 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"

 *

 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND

 * ANY EXPRESS 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 AUTHOR OR 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.

 *

 * The licence and distribution terms for any publically available version or

 * derivative of this code cannot be changed.  i.e. this code cannot simply be

 * copied and put under another distribution licence

 * [including the GNU Public Licence.]

 */

/*

 * NB: these functions have been "upgraded", the deprecated versions (which

 * are compatibility wrappers using these functions) are in rsa_depr.c. -

 * Geoff

 */

#include <stdio.h>

#include <time.h>

#include "cryptlib.h"

#include <openssl/bn.h>

#include <openssl/rsa.h>

#ifdef OPENSSL_FIPS

# include <openssl/fips.h>

extern int FIPS_rsa_x931_generate_key_ex(RSA *rsa, int bits, BIGNUM *e,

                                         BN_GENCB *cb);

#endif

static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value,

                              BN_GENCB *cb);

/*

 * NB: this wrapper would normally be placed in rsa_lib.c and the static

 * implementation would probably be in rsa_eay.c. Nonetheless, is kept here

 * so that we don't introduce a new linker dependency. Eg. any application

 * that wasn't previously linking object code related to key-generation won't

 * have to now just because key-generation is part of RSA_METHOD.

 */

int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)

{

#ifdef OPENSSL_FIPS

    if (FIPS_mode() && !(rsa->meth->flags & RSA_FLAG_FIPS_METHOD)

        && !(rsa->flags & RSA_FLAG_NON_FIPS_ALLOW)) {

        RSAerr(RSA_F_RSA_GENERATE_KEY_EX, RSA_R_NON_FIPS_RSA_METHOD);

        return 0;

    }

#endif

    if (rsa->meth->rsa_keygen)

        return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);

#ifdef OPENSSL_FIPS

    if (FIPS_mode())

        return FIPS_rsa_x931_generate_key_ex(rsa, bits, e_value, cb);

#endif

    return rsa_builtin_keygen(rsa, bits, e_value, cb);

}

static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value,

                              BN_GENCB *cb)

{

    BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *r3 = NULL, *tmp;

    BIGNUM local_r0, local_d, local_p;

    BIGNUM *pr0, *d, *p;

    int bitsp, bitsq, ok = -1, n = 0;

    BN_CTX *ctx = NULL;

    ctx = BN_CTX_new();

    if (ctx == NULL)

        goto err;

    BN_CTX_start(ctx);

    r0 = BN_CTX_get(ctx);

    r1 = BN_CTX_get(ctx);

    r2 = BN_CTX_get(ctx);

    r3 = BN_CTX_get(ctx);

    if (r3 == NULL)

        goto err;

    bitsp = (bits + 1) / 2;

    bitsq = bits - bitsp;

    /* We need the RSA components non-NULL */

    if (!rsa->n && ((rsa->n = BN_new()) == NULL))

        goto err;

    if (!rsa->d && ((rsa->d = BN_new()) == NULL))

        goto err;

    if (!rsa->e && ((rsa->e = BN_new()) == NULL))

        goto err;

    if (!rsa->p && ((rsa->p = BN_new()) == NULL))

        goto err;

    if (!rsa->q && ((rsa->q = BN_new()) == NULL))

        goto err;

    if (!rsa->dmp1 && ((rsa->dmp1 = BN_new()) == NULL))

        goto err;

    if (!rsa->dmq1 && ((rsa->dmq1 = BN_new()) == NULL))

        goto err;

    if (!rsa->iqmp && ((rsa->iqmp = BN_new()) == NULL))

        goto err;

    if (BN_copy(rsa->e, e_value) == NULL)

        goto err;

    /* generate p and q */

    for (;;) {

        if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb))

            goto err;

        if (!BN_sub(r2, rsa->p, BN_value_one()))

            goto err;

        if (!BN_gcd(r1, r2, rsa->e, ctx))

            goto err;

        if (BN_is_one(r1))

            break;

        if (!BN_GENCB_call(cb, 2, n++))

            goto err;

    }

    if (!BN_GENCB_call(cb, 3, 0))

        goto err;

    for (;;) {

        /*

         * When generating ridiculously small keys, we can get stuck

         * continually regenerating the same prime values. Check for this and

         * bail if it happens 3 times.

         */

        unsigned int degenerate = 0;

        do {

            if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, cb))

                goto err;

        } while ((BN_cmp(rsa->p, rsa->q) == 0) && (++degenerate < 3));

        if (degenerate == 3) {

            ok = 0;             /* we set our own err */

            RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL);

            goto err;

        }

        if (!BN_sub(r2, rsa->q, BN_value_one()))

            goto err;

        if (!BN_gcd(r1, r2, rsa->e, ctx))

            goto err;

        if (BN_is_one(r1))

            break;

        if (!BN_GENCB_call(cb, 2, n++))

            goto err;

    }

    if (!BN_GENCB_call(cb, 3, 1))

        goto err;

    if (BN_cmp(rsa->p, rsa->q) < 0) {

        tmp = rsa->p;

        rsa->p = rsa->q;

        rsa->q = tmp;

    }

    /* calculate n */

    if (!BN_mul(rsa->n, rsa->p, rsa->q, ctx))

        goto err;

    /* calculate d */

    if (!BN_sub(r1, rsa->p, BN_value_one()))

        goto err;               /* p-1 */

    if (!BN_sub(r2, rsa->q, BN_value_one()))

        goto err;               /* q-1 */

    if (!BN_mul(r0, r1, r2, ctx))

        goto err;               /* (p-1)(q-1) */

    if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {

        pr0 = &local_r0;

        BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);

    } else

        pr0 = r0;

    if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx))

        goto err;               /* d */

    /* set up d for correct BN_FLG_CONSTTIME flag */

    if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {

        d = &local_d;

        BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);

    } else

        d = rsa->d;

    /* calculate d mod (p-1) */

    if (!BN_mod(rsa->dmp1, d, r1, ctx))

        goto err;

    /* calculate d mod (q-1) */

    if (!BN_mod(rsa->dmq1, d, r2, ctx))

        goto err;

    /* calculate inverse of q mod p */

    if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {

        p = &local_p;

        BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);

    } else

        p = rsa->p;

    if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx))

        goto err;

    ok = 1;

 err:

    if (ok == -1) {

        RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN);

        ok = 0;

    }

    if (ctx != NULL) {

        BN_CTX_end(ctx);

        BN_CTX_free(ctx);

    }

    return ok;

}