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add DSA key generation

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This commit is contained in:
Werner Koch 1998-05-05 20:34:20 +00:00
parent 42b03f6ebd
commit 69cf10ffab
17 changed files with 324 additions and 29 deletions
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53
cipher/primegen.c
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@ -63,37 +63,49 @@ generate_public_prime( unsigned nbits )
* 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( unsigned pbits, unsigned qbits, MPI g, MPI **ret_factors )
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 */
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 )
if( !n || (mode==1 && n < 2) )
log_fatal("can't gen prime with pbits=%u qbits=%u\n", pbits, qbits );
fbits = (pbits - qbits -1) / n;
while( qbits + n*fbits < 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 n=%d\n",
pbits, qbits, fbits, n );
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 );
@ -139,6 +151,8 @@ generate_elg_prime( unsigned pbits, unsigned qbits, MPI g, MPI **ret_factors )
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 );
@ -171,18 +185,30 @@ generate_elg_prime( unsigned pbits, unsigned qbits, MPI g, MPI **ret_factors )
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+1) * sizeof **ret_factors );
for(i=0; i < n; i++ )
(*ret_factors)[i] = mpi_copy( factors[i] );
*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)*/
@ -190,6 +216,8 @@ generate_elg_prime( unsigned pbits, unsigned qbits, MPI g, MPI **ret_factors )
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 );
@ -230,6 +258,7 @@ generate_elg_prime( unsigned pbits, unsigned qbits, MPI g, MPI **ret_factors )
}
static MPI
gen_prime( unsigned nbits, int secret, int randomlevel )
{