Git initHEAD2.0_alphamaster2.0alpha1.0_post

1 files changed, 594 insertions, 0 deletions

diff --git a/cipher/primegen.c b/cipher/primegen.c
new file mode 100644
index 0000000..0662d39
--- /dev/null
+++ b/cipher/primegen.c
@@ -0,0 +1,594 @@
+/* primegen.c - prime number generator
+ *	Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+ * USA.
+ *
+ * ***********************************************************************
+ * The algorithm used to generate practically save primes is due to
+ * Lim and Lee as described in the CRYPTO '97 proceedings (ISBN3540633847)
+ * page 260.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include "util.h"
+#include "mpi.h"
+#include "cipher.h"
+#include "i18n.h"
+
+static int no_of_small_prime_numbers;
+static MPI gen_prime( unsigned	nbits, int mode, int randomlevel );
+static int check_prime( MPI prime, MPI val_2 );
+static int is_prime( MPI n, int steps, int *count );
+static void m_out_of_n( char *array, int m, int n );
+
+static void (*progress_cb) ( void *, int );
+static void *progress_cb_data;
+
+void
+register_primegen_progress ( void (*cb)( void *, int), void *cb_data )
+{
+    progress_cb = cb;
+    progress_cb_data = cb_data;
+}
+
+
+static void
+progress( int c )
+{
+    if ( progress_cb )
+	progress_cb ( progress_cb_data, c );
+    else
+	fputc( c, stderr );
+}
+
+
+/****************
+ * Generate a prime number (stored in secure memory)
+ */
+MPI
+generate_secret_prime( unsigned  nbits )
+{
+    MPI prime;
+
+    prime = gen_prime( nbits, 1, 2 );
+    progress('\n');
+    return prime;
+}
+
+MPI
+generate_public_prime( unsigned  nbits )
+{
+    MPI prime;
+
+    prime = gen_prime( nbits, 0, 2 );
+    progress('\n');
+    return prime;
+}
+
+
+/****************
+ * We do not need to use the strongest RNG because we gain no extra
+ * security from it - The prime number is public and we could also
+ * offer the factors for those who are willing to check that it is
+ * indeed a strong prime.
+ *
+ * mode 0: Standard
+ *	1: Make sure that at least one factor is of size qbits.
+ */
+MPI
+generate_elg_prime( int mode, unsigned pbits, unsigned qbits,
+		    MPI g, MPI **ret_factors )
+{
+    int n;  /* number of factors */
+    int m;  /* number of primes in pool */
+    unsigned fbits; /* length of prime factors */
+    MPI *factors; /* current factors */
+    MPI *pool;	/* pool of primes */
+    MPI q;	/* first prime factor (variable)*/
+    MPI prime;	/* prime test value */
+    MPI q_factor; /* used for mode 1 */
+    byte *perms = NULL;
+    int i, j;
+    int count1, count2;
+    unsigned nprime;
+    unsigned req_qbits = qbits; /* the requested q bits size */
+    MPI val_2  = mpi_alloc_set_ui( 2 );
+
+    /* find number of needed prime factors */
+    for(n=1; (pbits - qbits - 1) / n  >= qbits; n++ )
+	;
+    n--;
+    if( !n || (mode==1 && n < 2) )
+	log_fatal(_("can't gen prime with pbits=%u qbits=%u\n"),
+                  pbits, qbits );
+    if( mode == 1 ) {
+	n--;
+	fbits = (pbits - 2*req_qbits -1) / n;
+	qbits =  pbits - req_qbits - n*fbits;
+    }
+    else {
+	fbits = (pbits - req_qbits -1) / n;
+	qbits = pbits - n*fbits;
+    }
+    if( DBG_CIPHER )
+	log_debug("gen prime: pbits=%u qbits=%u fbits=%u/%u n=%d\n",
+		    pbits, req_qbits, qbits, fbits, n  );
+    prime = mpi_alloc( (pbits + BITS_PER_MPI_LIMB - 1) /  BITS_PER_MPI_LIMB );
+    q = gen_prime( qbits, 0, 0 );
+    q_factor = mode==1? gen_prime( req_qbits, 0, 0 ) : NULL;
+
+    /* allocate an array to hold the factors + 2 for later usage */
+    factors = xmalloc_clear( (n+2) * sizeof *factors );
+
+    /* make a pool of 3n+5 primes (this is an arbitrary value) */
+    m = n*3+5;
+    if( mode == 1 )
+	m += 5; /* need some more for DSA */
+    if( m < 25 )
+	m = 25;
+    pool = xmalloc_clear( m * sizeof *pool );
+
+    /* permutate over the pool of primes */
+    count1=count2=0;
+    do {
+      next_try:
+	if( !perms ) {
+	    /* allocate new primes */
+	    for(i=0; i < m; i++ ) {
+		mpi_free(pool[i]);
+		pool[i] = NULL;
+	    }
+	    /* init m_out_of_n() */
+	    perms = xmalloc_clear( m );
+	    for(i=0; i < n; i++ ) {
+		perms[i] = 1;
+		pool[i] = gen_prime( fbits, 0, 0 );
+		factors[i] = pool[i];
+	    }
+	}
+	else {
+	    m_out_of_n( perms, n, m );
+	    for(i=j=0; i < m && j < n ; i++ )
+		if( perms[i] ) {
+		    if( !pool[i] )
+			pool[i] = gen_prime( fbits, 0, 0 );
+		    factors[j++] = pool[i];
+		}
+	    if( i == n ) {
+		xfree(perms); perms = NULL;
+		progress('!');
+		goto next_try;	/* allocate new primes */
+	    }
+	}
+
+	mpi_set( prime, q );
+	mpi_mul_ui( prime, prime, 2 );
+	if( mode == 1 )
+	    mpi_mul( prime, prime, q_factor );
+	for(i=0; i < n; i++ )
+	    mpi_mul( prime, prime, factors[i] );
+	mpi_add_ui( prime, prime, 1 );
+	nprime = mpi_get_nbits(prime);
+	if( nprime < pbits ) {
+	    if( ++count1 > 20 ) {
+		count1 = 0;
+		qbits++;
+		progress('>');
+                mpi_free (q);
+		q = gen_prime( qbits, 0, 0 );
+		goto next_try;
+	    }
+	}
+	else
+	    count1 = 0;
+	if( nprime > pbits ) {
+	    if( ++count2 > 20 ) {
+		count2 = 0;
+		qbits--;
+		progress('<');
+                mpi_free (q);
+		q = gen_prime( qbits, 0, 0 );
+		goto next_try;
+	    }
+	}
+	else
+	    count2 = 0;
+    } while( !(nprime == pbits && check_prime( prime, val_2 )) );
+
+    if( DBG_CIPHER ) {
+	progress('\n');
+	log_mpidump( "prime    : ", prime );
+	log_mpidump( "factor  q: ", q );
+	if( mode == 1 )
+	    log_mpidump( "factor q0: ", q_factor );
+	for(i=0; i < n; i++ )
+	    log_mpidump( "factor pi: ", factors[i] );
+	log_debug("bit sizes: prime=%u, q=%u", mpi_get_nbits(prime), mpi_get_nbits(q) );
+	if( mode == 1 )
+	    fprintf(stderr, ", q0=%u", mpi_get_nbits(q_factor) );
+	for(i=0; i < n; i++ )
+	    fprintf(stderr, ", p%d=%u", i, mpi_get_nbits(factors[i]) );
+	progress('\n');
+    }
+
+    if( ret_factors ) { /* caller wants the factors */
+	*ret_factors = xmalloc_clear( (n+2) * sizeof **ret_factors);
+        i = 0;
+	if( mode == 1 ) {
+	    (*ret_factors)[i++] = mpi_copy( q_factor );
+	    for(; i <= n; i++ )
+		(*ret_factors)[i] = mpi_copy( factors[i-1] );
+	}
+	else {
+	    for(; i < n; i++ )
+		(*ret_factors)[i] = mpi_copy( factors[i] );
+	}
+    }
+
+    if( g ) { /* create a generator (start with 3)*/
+	MPI tmp   = mpi_alloc( mpi_get_nlimbs(prime) );
+	MPI b	  = mpi_alloc( mpi_get_nlimbs(prime) );
+	MPI pmin1 = mpi_alloc( mpi_get_nlimbs(prime) );
+
+	if( mode == 1 )
+	    BUG(); /* not yet implemented */
+	factors[n] = q;
+	factors[n+1] = mpi_alloc_set_ui(2);
+	mpi_sub_ui( pmin1, prime, 1 );
+	mpi_set_ui(g,2);
+	do {
+	    mpi_add_ui(g, g, 1);
+	    if( DBG_CIPHER ) {
+		log_debug("checking g: ");
+		mpi_print( stderr, g, 1 );
+	    }
+	    else
+		progress('^');
+	    for(i=0; i < n+2; i++ ) {
+		/*fputc('~', stderr);*/
+		mpi_fdiv_q(tmp, pmin1, factors[i] );
+		/* (no mpi_pow(), but it is okay to use this with mod prime) */
+		mpi_powm(b, g, tmp, prime );
+		if( !mpi_cmp_ui(b, 1) )
+		    break;
+	    }
+	    if( DBG_CIPHER )
+		progress('\n');
+	} while( i < n+2 );
+	mpi_free(factors[n+1]);
+	mpi_free(tmp);
+	mpi_free(b);
+	mpi_free(pmin1);
+    }
+    if( !DBG_CIPHER )
+	progress('\n');
+
+    xfree( factors );	/* (factors are shallow copies) */
+    for(i=0; i < m; i++ )
+	mpi_free( pool[i] );
+    xfree( pool );
+    xfree(perms);
+    mpi_free(val_2);
+    mpi_free(q);
+    return prime;
+}
+
+
+
+static MPI
+gen_prime( unsigned int nbits, int secret, int randomlevel )
+{
+    unsigned  nlimbs;
+    MPI prime, ptest, pminus1, val_2, val_3, result;
+    int i;
+    unsigned x, step;
+    int count1, count2;
+    int *mods;
+
+    if( 0 && DBG_CIPHER )
+	log_debug("generate a prime of %u bits ", nbits );
+
+    if (nbits < 16)
+      {
+        log_error (_("can't generate a prime with less than %d bits\n"), 16);
+        exit (2);
+      }
+
+    if( !no_of_small_prime_numbers ) {
+	for(i=0; small_prime_numbers[i]; i++ )
+	    no_of_small_prime_numbers++;
+    }
+    mods = xmalloc( no_of_small_prime_numbers * sizeof *mods );
+    /* make nbits fit into MPI implementation */
+    nlimbs = (nbits + BITS_PER_MPI_LIMB - 1) /	BITS_PER_MPI_LIMB;
+    val_2  = mpi_alloc_set_ui( 2 );
+    val_3 = mpi_alloc_set_ui( 3);
+    prime  = secret? mpi_alloc_secure( nlimbs ): mpi_alloc( nlimbs );
+    result = mpi_alloc_like( prime );
+    pminus1= mpi_alloc_like( prime );
+    ptest  = mpi_alloc_like( prime );
+    count1 = count2 = 0;
+    for(;;) {  /* try forvever */
+	int dotcount=0;
+
+	/* generate a random number */
+	{   char *p = get_random_bits( nbits, randomlevel, secret );
+	    mpi_set_buffer( prime, p, (nbits+7)/8, 0 );
+	    xfree(p);
+	}
+
+	/* Set high order bit to 1, set low order bit to 0.
+           If we are generating a secret prime we are most probably
+           doing that for RSA, to make sure that the modulus does have
+           the requested keysize we set the 2 high order bits */
+	mpi_set_highbit( prime, nbits-1 );
+        if (secret)
+          mpi_set_bit (prime, nbits-2);
+	mpi_set_bit( prime, 0 );
+
+	/* calculate all remainders */
+	for(i=0; (x = small_prime_numbers[i]); i++ )
+	    mods[i] = mpi_fdiv_r_ui(NULL, prime, x);
+
+	/* now try some primes starting with prime */
+	for(step=0; step < 20000; step += 2 ) {
+	    /* check against all the small primes we have in mods */
+	    count1++;
+	    for(i=0; (x = small_prime_numbers[i]); i++ ) {
+		while( mods[i] + step >= x )
+		    mods[i] -= x;
+		if( !(mods[i] + step) )
+		    break;
+	    }
+	    if( x )
+		continue;   /* found a multiple of an already known prime */
+
+	    mpi_add_ui( ptest, prime, step );
+
+	    /* do a faster Fermat test */
+	    count2++;
+	    mpi_sub_ui( pminus1, ptest, 1);
+	    mpi_powm( result, val_2, pminus1, ptest );
+	    if( !mpi_cmp_ui( result, 1 ) ) { /* not composite */
+		/* perform stronger tests */
+		if( is_prime(ptest, 5, &count2 ) ) {
+		    if( !mpi_test_bit( ptest, nbits-1 ) ) {
+			progress('\n');
+			log_debug("overflow in prime generation\n");
+			break; /* step loop, continue with a new prime */
+		    }
+
+		    mpi_free(val_2);
+		    mpi_free(val_3);
+		    mpi_free(result);
+		    mpi_free(pminus1);
+		    mpi_free(prime);
+		    xfree(mods);
+		    return ptest;
+		}
+	    }
+	    if( ++dotcount == 10 ) {
+		progress('.');
+		dotcount = 0;
+	    }
+	}
+	progress(':'); /* restart with a new random value */
+    }
+}
+
+/****************
+ * Returns: true if this may be a prime
+ */
+static int
+check_prime( MPI prime, MPI val_2 )
+{
+    int i;
+    unsigned x;
+    int count=0;
+
+    /* check against small primes */
+    for(i=0; (x = small_prime_numbers[i]); i++ ) {
+	if( mpi_divisible_ui( prime, x ) )
+	    return 0;
+    }
+
+    /* a quick fermat test */
+    {
+	MPI result = mpi_alloc_like( prime );
+	MPI pminus1 = mpi_alloc_like( prime );
+	mpi_sub_ui( pminus1, prime, 1);
+	mpi_powm( result, val_2, pminus1, prime );
+	mpi_free( pminus1 );
+	if( mpi_cmp_ui( result, 1 ) ) { /* if composite */
+	    mpi_free( result );
+	    progress('.');
+	    return 0;
+	}
+	mpi_free( result );
+    }
+
+    /* perform stronger tests */
+    if( is_prime(prime, 5, &count ) )
+	return 1; /* is probably a prime */
+    progress('.');
+    return 0;
+}
+
+
+/****************
+ * Return true if n is probably a prime
+ */
+static int
+is_prime( MPI n, int steps, int *count )
+{
+    MPI x = mpi_alloc( mpi_get_nlimbs( n ) );
+    MPI y = mpi_alloc( mpi_get_nlimbs( n ) );
+    MPI z = mpi_alloc( mpi_get_nlimbs( n ) );
+    MPI nminus1 = mpi_alloc( mpi_get_nlimbs( n ) );
+    MPI a2 = mpi_alloc_set_ui( 2 );
+    MPI q;
+    unsigned i, j, k;
+    int rc = 0;
+    unsigned nbits = mpi_get_nbits( n );
+
+    mpi_sub_ui( nminus1, n, 1 );
+
+    /* find q and k, so that n = 1 + 2^k * q */
+    q = mpi_copy( nminus1 );
+    k = mpi_trailing_zeros( q );
+    mpi_tdiv_q_2exp(q, q, k);
+
+    for(i=0 ; i < steps; i++ ) {
+	++*count;
+	if( !i ) {
+	    mpi_set_ui( x, 2 );
+	}
+	else {
+            char *p;
+            
+            p = get_random_bits( nbits, 0, 0 );
+            mpi_set_buffer( x, p, (nbits+7)/8, 0 );
+            xfree(p);
+
+	    /* Make sure that the number is smaller than the prime
+	     * and keep the randomness of the high bit.  */
+	    if( mpi_test_bit( x, nbits-2 ) ) {
+		mpi_set_highbit( x, nbits-2 ); /* Clear all higher bits */
+	    }
+	    else {
+		mpi_set_highbit( x, nbits-2 );
+		mpi_clear_bit( x, nbits-2 );
+	    }
+	    assert( mpi_cmp( x, nminus1 ) < 0 && mpi_cmp_ui( x, 1 ) > 0 );
+	}
+	mpi_powm( y, x, q, n);
+	if( mpi_cmp_ui(y, 1) && mpi_cmp( y, nminus1 ) ) {
+	    for( j=1; j < k && mpi_cmp( y, nminus1 ); j++ ) {
+		mpi_powm(y, y, a2, n);
+		if( !mpi_cmp_ui( y, 1 ) )
+		    goto leave; /* not a prime */
+	    }
+	    if( mpi_cmp( y, nminus1 ) )
+		goto leave; /* not a prime */
+	}
+	progress('+');
+    }
+    rc = 1; /* may be a prime */
+
+  leave:
+    mpi_free( x );
+    mpi_free( y );
+    mpi_free( z );
+    mpi_free( nminus1 );
+    mpi_free( q );
+    mpi_free (a2);
+
+    return rc;
+}
+
+
+static void
+m_out_of_n( char *array, int m, int n )
+{
+    int i=0, i1=0, j=0, jp=0,  j1=0, k1=0, k2=0;
+
+    if( !m || m >= n )
+	return;
+
+    if( m == 1 ) { /* special case */
+	for(i=0; i < n; i++ )
+	    if( array[i] ) {
+		array[i++] = 0;
+		if( i >= n )
+		    i = 0;
+		array[i] = 1;
+		return;
+	    }
+	BUG();
+    }
+
+    for(j=1; j < n; j++ ) {
+	if( array[n-1] == array[n-j-1] )
+	    continue;
+	j1 = j;
+	break;
+    }
+
+    if( m & 1 ) { /* m is odd */
+	if( array[n-1] ) {
+	    if( j1 & 1 ) {
+		k1 = n - j1;
+		k2 = k1+2;
+		if( k2 > n )
+		    k2 = n;
+		goto leave;
+	    }
+	    goto scan;
+	}
+	k2 = n - j1 - 1;
+	if( k2 == 0 ) {
+	    k1 = i;
+	    k2 = n - j1;
+	}
+	else if( array[k2] && array[k2-1] )
+	    k1 = n;
+	else
+	    k1 = k2 + 1;
+    }
+    else { /* m is even */
+	if( !array[n-1] ) {
+	    k1 = n - j1;
+	    k2 = k1 + 1;
+	    goto leave;
+	}
+
+	if( !(j1 & 1) ) {
+	    k1 = n - j1;
+	    k2 = k1+2;
+	    if( k2 > n )
+		k2 = n;
+	    goto leave;
+	}
+      scan:
+	jp = n - j1 - 1;
+	for(i=1; i <= jp; i++ ) {
+	    i1 = jp + 2 - i;
+	    if( array[i1-1]  ) {
+		if( array[i1-2] ) {
+		    k1 = i1 - 1;
+		    k2 = n - j1;
+		}
+		else {
+		    k1 = i1 - 1;
+		    k2 = n + 1 - j1;
+		}
+		goto leave;
+	    }
+	}
+	k1 = 1;
+	k2 = n + 1 - m;
+    }
+  leave:
+    array[k1-1] = !array[k1-1];
+    array[k2-1] = !array[k2-1];
+}
+