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See ChangeLog: Fri Jul 2 11:45:54 CEST 1999 Werner Koch

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This commit is contained in:
Werner Koch 1999-07-02 09:50:57 +00:00
parent 28eb86c006
commit 86abac78a2
15 changed files with 366 additions and 64 deletions
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41
cipher/elgamal.c
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@ -108,7 +108,9 @@ gen_k( MPI p )
MPI k = mpi_alloc_secure( 0 );
MPI temp = mpi_alloc( mpi_get_nlimbs(p) );
MPI p_1 = mpi_copy(p);
unsigned nbits = mpi_get_nbits(p);
unsigned int nbits = mpi_get_nbits(p);
unsigned int nbytes = (nbits+7)/8;
char *rndbuf = NULL;
if( DBG_CIPHER )
log_debug("choosing a random k ");
@ -116,9 +118,21 @@ gen_k( MPI p )
for(;;) {
if( DBG_CIPHER )
progress('.');
{ char *pp = get_random_bits( nbits, 1, 1 );
mpi_set_buffer( k, pp, (nbits+7)/8, 0 );
if( !rndbuf || nbits < 32 ) {
m_free(rndbuf);
rndbuf = get_random_bits( nbits, 1, 1 );
}
else { /* change only some of the higher bits */
/* we could imporove this by directly requesting more memory
* at the first call to get_random_bits() and use this the here
* maybe it is easier to do this directly in random.c */
char *pp = get_random_bits( 32, 1, 1 );
memcpy( rndbuf,pp, 4 );
m_free(pp);
}
mpi_set_buffer( k, rndbuf, nbytes, 0 );
for(;;) {
/* make sure that the number is of the exact lenght */
if( mpi_test_bit( k, nbits-1 ) )
mpi_set_highbit( k, nbits-1 );
@ -126,14 +140,23 @@ gen_k( MPI p )
mpi_set_highbit( k, nbits-1 );
mpi_clear_bit( k, nbits-1 );
}
if( !(mpi_cmp( k, p_1 ) < 0) ) { /* check: k < (p-1) */
if( DBG_CIPHER )
progress('+');
break; /* no */
}
if( !(mpi_cmp_ui( k, 0 ) > 0) ) { /* check: k > 0 */
if( DBG_CIPHER )
progress('-');
break; /* no */
}
if( mpi_gcd( temp, k, p_1 ) )
goto found; /* okay, k is relatively prime to (p-1) */
mpi_add_ui( k, k, 1 );
}
if( !(mpi_cmp( k, p_1 ) < 0) ) /* check: k < (p-1) */
continue; /* no */
if( !(mpi_cmp_ui( k, 0 ) > 0) ) /* check: k > 0 */
continue; /* no */
if( mpi_gcd( temp, k, p_1 ) )
break; /* okay, k is relatively prime to (p-1) */
}
found:
m_free(rndbuf);
if( DBG_CIPHER )
progress('\n');
mpi_free(p_1);