rsa_gen.c

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/* crypto/rsa/rsa_gen.c */
/* Copyright (C) 1995-1998 Eric Young ([email protected])
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young ([email protected]).
 * 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 ([email protected]).
 * 
 * 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 ([email protected])"
 *    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 ([email protected])"
 * 
 * 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>
#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_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;

    BN_copy(rsa->e, e_value);

    /* 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;
    }