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-rw-r--r--cipher/primegen.c557
1 files changed, 0 insertions, 557 deletions
diff --git a/cipher/primegen.c b/cipher/primegen.c
deleted file mode 100644
index e9484218..00000000
--- a/cipher/primegen.c
+++ /dev/null
@@ -1,557 +0,0 @@
-/* primegen.c - prime number generator
- * Copyright (C) 1998 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
- */
-
-#include <config.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <assert.h>
-#include "util.h"
-#include "mpi.h"
-#include "cipher.h"
-
-static int no_of_small_prime_numbers;
-static MPI gen_prime( unsigned nbits, int mode, int randomlevel );
-static int check_prime( MPI prime );
-static int is_prime( MPI n, int steps, int *count );
-static void m_out_of_n( char *array, int m, int n );
-
-
-/****************
- * Generate a prime number (stored in secure memory)
- */
-MPI
-generate_secret_prime( unsigned nbits )
-{
- MPI prime;
-
- prime = gen_prime( nbits, 1, 2 );
- fputc('\n', stderr);
- return prime;
-}
-
-MPI
-generate_public_prime( unsigned nbits )
-{
- MPI prime;
-
- prime = gen_prime( nbits, 0, 2 );
- fputc('\n', stderr);
- 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 */
-
- /* 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, 1 );
- q_factor = mode==1? gen_prime( req_qbits, 0, 1 ) : NULL;
-
- /* allocate an array to hold the factors + 2 for later usage */
- factors = m_alloc_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 = m_alloc_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 = m_alloc_clear( m );
- for(i=0; i < n; i++ ) {
- perms[i] = 1;
- pool[i] = gen_prime( fbits, 0, 1 );
- 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, 1 );
- factors[j++] = pool[i];
- }
- if( i == n ) {
- m_free(perms); perms = NULL;
- fputc('!', stderr);
- 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++;
- fputc('>', stderr);
- q = gen_prime( qbits, 0, 1 );
- goto next_try;
- }
- }
- else
- count1 = 0;
- if( nprime > pbits ) {
- if( ++count2 > 20 ) {
- count2 = 0;
- qbits--;
- fputc('<', stderr);
- q = gen_prime( qbits, 0, 1 );
- goto next_try;
- }
- }
- else
- count2 = 0;
- } while( !(nprime == pbits && check_prime( prime )) );
-
- if( DBG_CIPHER ) {
- putc('\n', stderr);
- 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]) );
- putc('\n', stderr);
- }
-
- if( ret_factors ) { /* caller wants the factors */
- *ret_factors = m_alloc_clear( (n+2) * sizeof **ret_factors);
- if( mode == 1 ) {
- i = 0;
- (*ret_factors)[i++] = mpi_copy( q_factor );
- for(; i <= n; i++ )
- (*ret_factors)[i] = mpi_copy( factors[i] );
- }
- 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
- fputc('^', stderr);
- 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 )
- fputc('\n', stderr);
- } while( i < n+2 );
- mpi_free(factors[n+1]);
- mpi_free(tmp);
- mpi_free(b);
- mpi_free(pmin1);
- }
- if( !DBG_CIPHER )
- putc('\n', stderr);
-
- m_free( factors ); /* (factors are shallow copies) */
- for(i=0; i < m; i++ )
- mpi_free( pool[i] );
- m_free( pool );
- m_free(perms);
- return prime;
-}
-
-
-
-static MPI
-gen_prime( unsigned nbits, int secret, int randomlevel )
-{
- unsigned nlimbs;
- MPI prime, val_2, val_3, result;
- int i;
- unsigned x, step;
- unsigned count1, count2;
- int *mods;
-
- if( 0 && DBG_CIPHER )
- log_debug("generate a prime of %u bits ", nbits );
-
- if( !no_of_small_prime_numbers ) {
- for(i=0; small_prime_numbers[i]; i++ )
- no_of_small_prime_numbers++;
- }
- mods = m_alloc( 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( nlimbs );
- mpi_set_ui(val_2, 2);
- val_3 = mpi_alloc( nlimbs );
- mpi_set_ui(val_3, 3);
- result = mpi_alloc( nlimbs );
- prime = secret? mpi_alloc_secure( nlimbs ): mpi_alloc( nlimbs );
- count1 = count2 = 0;
- /* enter (endless) loop */
- for(;;) {
- int dotcount=0;
-
- /* generate a random number */
- /*mpi_set_bytes( prime, nbits, get_random_byte, randomlevel );*/
- { char *p = get_random_bits( nbits, randomlevel, secret );
- mpi_set_buffer( prime, p, (nbits+7)/8, 0 );
- m_free(p);
- }
-
- /* set high order bit to 1, set low order bit to 1 */
- mpi_set_highbit( prime, nbits-1 );
- 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);
-
- 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 a already known prime */
-
- mpi_add_ui( prime, prime, step );
-
- #if 0
- /* do a Fermat test */
- count2++;
- mpi_powm( result, val_2, prime, prime );
- if( mpi_cmp_ui(result, 2) )
- continue; /* stepping (fermat test failed) */
- fputc('+', stderr);
- #endif
-
- /* perform stronger tests */
- if( is_prime(prime, 5, &count2 ) ) {
- if( !mpi_test_bit( prime, nbits-1 ) ) {
- if( 0 && DBG_CIPHER ) {
- fputc('\n', stderr);
- log_debug("overflow in prime generation\n");
- break; /* step loop, cont with a new prime */
- }
- }
-
- if( 0 && DBG_CIPHER ) {
- log_debug("performed %u simple and %u stronger tests\n",
- count1, count2 );
- log_mpidump("found prime: ", prime );
- }
-
- mpi_free(val_2);
- mpi_free(val_3);
- mpi_free(result);
- m_free(mods);
- return prime;
- }
- if( ++dotcount == 10 ) {
- fputc('.', stderr);
- dotcount = 0;
- }
- }
- fputc(':', stderr); /* restart with a new random value */
- }
-}
-
-/****************
- * Returns: true if this may be a prime
- */
-static int
-check_prime( MPI prime )
-{
- 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;
- }
-
- #if 0
- result = mpi_alloc( mpi_get_nlimbs(prime) );
- val_2 = mpi_alloc_set_ui( 2 );
- mpi_powm( result, val_2, prime, prime );
- if( mpi_cmp_ui(result, 2) ) {
- mpi_free(result);
- mpi_free(val_2);
- return 0;
- }
- mpi_free(result);
- mpi_free(val_2);
- fputc('+', stderr);
- #endif
-
- /* perform stronger tests */
- if( is_prime(prime, 5, &count ) )
- return 1; /* is probably a prime */
- fputc('.', stderr);
- 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 {
- /*mpi_set_bytes( x, nbits-1, get_random_byte, 0 );*/
- { char *p = get_random_bits( nbits, 0, 0 );
- mpi_set_buffer( x, p, (nbits+7)/8, 0 );
- m_free(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 */
- }
- fputc('+', stderr);
- }
- rc = 1; /* may be a prime */
-
- leave:
- mpi_free( x );
- mpi_free( y );
- mpi_free( z );
- mpi_free( nminus1 );
- mpi_free( q );
-
- 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];
-}
-
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