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See ChangeLog: Wed Sep 13 18:12:34 CEST 2000 Werner Koch

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Werner Koch 2000-09-13 16:11:24 +00:00
parent 3c3ad064b6
commit 8f6b40ff1c
6 changed files with 122 additions and 9 deletions
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6
cipher/ChangeLog
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@ -1,3 +1,9 @@
Wed Sep 13 18:12:34 CEST 2000 Werner Koch <wk@openit.de>
* rsa.c (secret): Speed up by using the CRT. For a 2k keys this
is about 3 times faster.
(stronger_key_check): New but unused code to check the secret key.
Wed Sep 6 17:55:47 CEST 2000 Werner Koch <wk@openit.de>
* rsa.c: Changed the comment about the patent.

93
cipher/rsa.c
View file

@ -98,7 +98,7 @@ generate( RSA_secret_key *sk, unsigned nbits )
MPI t1, t2;
MPI n; /* the public key */
MPI e; /* the exponent */
MPI phi; /* helper: (p-a)(q-1) */
MPI phi; /* helper: (p-1)(q-1) */
MPI g;
MPI f;
@ -201,19 +201,106 @@ public(MPI output, MPI input, RSA_public_key *pkey )
mpi_powm( output, input, pkey->e, pkey->n );
}
#if 0
static void
stronger_key_check ( RSA_secret_key *skey )
{
MPI t = mpi_alloc_secure ( 0 );
MPI t1 = mpi_alloc_secure ( 0 );
MPI t2 = mpi_alloc_secure ( 0 );
MPI phi = mpi_alloc_secure ( 0 );
/* check that n == p * q */
mpi_mul( t, skey->p, skey->q);
if (mpi_cmp( t, skey->n) )
log_info ( "RSA Oops: n != p * q\n" );
/* check that p is less than q */
if( mpi_cmp( skey->p, skey->q ) > 0 )
log_info ("RSA Oops: p >= q\n");
/* check that e divides neither p-1 nor q-1 */
mpi_sub_ui(t, skey->p, 1 );
mpi_fdiv_r(t, t, skey->e );
if ( !mpi_cmp_ui( t, 0) )
log_info ( "RSA Oops: e divides p-1\n" );
mpi_sub_ui(t, skey->q, 1 );
mpi_fdiv_r(t, t, skey->e );
if ( !mpi_cmp_ui( t, 0) )
log_info ( "RSA Oops: e divides q-1\n" );
/* check that d is correct */
mpi_sub_ui( t1, skey->p, 1 );
mpi_sub_ui( t2, skey->q, 1 );
mpi_mul( phi, t1, t2 );
mpi_gcd(t, t1, t2);
mpi_fdiv_q(t, phi, t);
mpi_invm(t, skey->e, t );
if ( mpi_cmp(t, skey->d ) )
log_info ( "RSA Oops: d is wrong\n");
/* check for crrectness of u */
mpi_invm(t, skey->p, skey->q );
if ( mpi_cmp(t, skey->u ) )
log_info ( "RSA Oops: u is wrong\n");
log_info ( "RSA secret key check finished\n");
mpi_free (t);
mpi_free (t1);
mpi_free (t2);
mpi_free (phi);
}
#endif
/****************
* Secret key operation. Encrypt INPUT with SKEY and put result into OUTPUT.
*
* m = c^d mod n
*
* Where m is OUTPUT, c is INPUT and d,n are elements of PKEY.
* Or faster:
*
* FIXME: We should better use the Chinese Remainder Theorem
* m1 = c ^ (d mod (p-1)) mod p
* m2 = c ^ (d mod (q-1)) mod q
* h = u * (m2 - m1) mod q
* m = m1 + h * p
*
* Where m is OUTPUT, c is INPUT and d,n,p,q,u are elements of SKEY.
*/
static void
secret(MPI output, MPI input, RSA_secret_key *skey )
{
#if 0
mpi_powm( output, input, skey->d, skey->n );
#else
MPI m1 = mpi_alloc_secure( mpi_get_nlimbs(skey->n)+1 );
MPI m2 = mpi_alloc_secure( mpi_get_nlimbs(skey->n)+1 );
MPI h = mpi_alloc_secure( mpi_get_nlimbs(skey->n)+1 );
/* m1 = c ^ (d mod (p-1)) mod p */
mpi_sub_ui( h, skey->p, 1 );
mpi_fdiv_r( h, skey->d, h );
mpi_powm( m1, input, h, skey->p );
/* m2 = c ^ (d mod (q-1)) mod q */
mpi_sub_ui( h, skey->q, 1 );
mpi_fdiv_r( h, skey->d, h );
mpi_powm( m2, input, h, skey->q );
/* h = u * ( m2 - m1 ) mod q */
mpi_sub( h, m2, m1 );
if ( mpi_is_neg( h ) )
mpi_add ( h, h, skey->q );
mpi_mulm( h, skey->u, h, skey->q );
/* m = m2 + h * p */
mpi_mul ( h, h, skey->p );
mpi_add ( output, m1, h );
/* ready */
mpi_free ( h );
mpi_free ( m1 );
mpi_free ( m2 );
#endif
}