security-and-privacy/gnupg
security-and-privacy/gnupg
1
0
Fork 0
mirror of git://git.gnupg.org/gnupg.git synced 2025-07-02 22:46:30 +02:00
Code Activity

some cleanups

Browse source
This commit is contained in:
Werner Koch 1998-03-19 15:27:29 +00:00
parent 98211af4a7
commit 6b91e7762c
49 changed files with 1737 additions and 452 deletions
Download patch file Download diff file Expand all files Collapse all files

60
cipher/dsa.c
View file

@ -27,6 +27,32 @@
#include "cipher.h"
#include "dsa.h"
/****************
* Generate a random secret exponent k less than q
*/
static MPI
gen_k( MPI q )
{
MPI k = mpi_alloc_secure( mpi_get_nlimbs(q) );
unsigned nbits = mpi_get_nbits(q);
if( DBG_CIPHER )
log_debug("choosing a random k ");
for(;;) {
if( DBG_CIPHER )
fputc('.', stderr);
mpi_set_bytes( k, nbits , get_random_byte, 1 );
if( !(mpi_cmp( k, q ) < 0) ) /* check: k < q */
continue; /* no */
if( !(mpi_cmp_ui( k, 0 ) > 0) ) /* check: k > 0 */
continue; /* no */
break; /* okay */
}
if( DBG_CIPHER )
fputc('\n', stderr);
return k;
}
void
dsa_free_public_key( DSA_public_key *pk )
@ -67,12 +93,36 @@ dsa_check_secret_key( DSA_secret_key *sk )
/****************
* Make a DSA signature out of INPUT
* Make a DSA signature from HASH and put it into r and s.
*/
void
dsa_sign(MPI r, MPI s, MPI input, DSA_secret_key *skey )
dsa_sign(MPI r, MPI s, MPI hash, DSA_secret_key *skey )
{
MPI k;
MPI kinv;
MPI tmp;
/* select a random k with 0 < k < q */
k = gen_k( skey->q );
/* r = (a^k mod p) mod q */
mpi_powm( r, skey->g, k, skey->p );
mpi_fdiv_r( r, r, skey->q );
/* kinv = k^(-1) mod q */
kinv = mpi_alloc( mpi_get_nlimbs(k) );
mpi_invm(kinv, k, skey->q );
/* s = (kinv * ( hash + x * r)) mod q */
tmp = mpi_alloc( mpi_get_nlimbs(skey->p) );
mpi_mul( tmp, skey->x, r );
mpi_add( tmp, tmp, hash );
mpi_mulm( s , kinv, tmp, skey->q );
mpi_free(k);
mpi_free(kinv);
mpi_free(tmp);
}
@ -80,7 +130,7 @@ dsa_sign(MPI r, MPI s, MPI input, DSA_secret_key *skey )
* Returns true if the signature composed from R and S is valid.
*/
int
dsa_verify(MPI r, MPI s, MPI input, DSA_public_key *pkey )
dsa_verify(MPI r, MPI s, MPI hash, DSA_public_key *pkey )
{
int rc;
MPI w, u1, u2, v;
@ -100,8 +150,8 @@ dsa_verify(MPI r, MPI s, MPI input, DSA_public_key *pkey )
/* w = s^(-1) mod q */
mpi_invm( w, s, pkey->q );
/* u1 = (input * w) mod q */
mpi_mulm( u1, input, w, pkey->q );
/* u1 = (hash * w) mod q */
mpi_mulm( u1, hash, w, pkey->q );
/* u2 = r * w mod q */
mpi_mulm( u2, r, w, pkey->q );