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-rw-r--r--src/pluto/dsa.c476
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diff --git a/src/pluto/dsa.c b/src/pluto/dsa.c
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--- a/src/pluto/dsa.c
+++ /dev/null
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-/* dsa.c - DSA signature scheme
- * 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
- */
-
-#ifdef PLUTO
-#include <gmp.h>
-#include <freeswan.h>
-#include "constants.h"
-#include "defs.h"
-#include "log.h"
-#include "rnd.h"
-#include "gcryptfix.h"
-#else /*! PLUTO */
-/* #include <config.h> */
-#endif /* !PLUTO */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-#ifndef PLUTO
-/* #include <assert.h> */
-/* #include "util.h" */
-/* #include "mpi.h" */
-/* #include "cipher.h" */
-#endif
-
-#include "dsa.h"
-
-typedef struct {
- MPI p; /* prime */
- MPI q; /* group order */
- MPI g; /* group generator */
- MPI y; /* g^x mod p */
-} DSA_public_key;
-
-
-typedef struct {
- MPI p; /* prime */
- MPI q; /* group order */
- MPI g; /* group generator */
- MPI y; /* g^x mod p */
- MPI x; /* secret exponent */
-} DSA_secret_key;
-
-
-static MPI gen_k( MPI q );
-static void test_keys( DSA_secret_key *sk, unsigned qbits );
-static int check_secret_key( DSA_secret_key *sk );
-static void generate( DSA_secret_key *sk, unsigned nbits, MPI **ret_factors );
-static void sign(MPI r, MPI s, MPI input, DSA_secret_key *skey);
-static int verify(MPI r, MPI s, MPI input, DSA_public_key *pkey);
-
-static void
-progress( int c )
-{
- fputc( c, stderr );
-}
-
-
-/****************
- * 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 int nbits = mpi_get_nbits(q);
- unsigned int nbytes = (nbits+7)/8;
- char *rndbuf = NULL;
-
- if( DBG_CIPHER )
- log_debug("choosing a random k ");
- for(;;) {
- if( DBG_CIPHER )
- progress('.');
-
- 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 );
- if( mpi_test_bit( k, nbits-1 ) )
- mpi_set_highbit( k, nbits-1 );
- else {
- mpi_set_highbit( k, nbits-1 );
- mpi_clear_bit( k, nbits-1 );
- }
-
- if( !(mpi_cmp( k, q ) < 0) ) { /* check: k < q */
- if( DBG_CIPHER )
- progress('+');
- continue; /* no */
- }
- if( !(mpi_cmp_ui( k, 0 ) > 0) ) { /* check: k > 0 */
- if( DBG_CIPHER )
- progress('-');
- continue; /* no */
- }
- break; /* okay */
- }
- m_free(rndbuf);
- if( DBG_CIPHER )
- progress('\n');
-
- return k;
-}
-
-
-static void
-test_keys( DSA_secret_key *sk, unsigned qbits )
-{
- DSA_public_key pk;
- MPI test = mpi_alloc( qbits / BITS_PER_MPI_LIMB );
- MPI out1_a = mpi_alloc( qbits / BITS_PER_MPI_LIMB );
- MPI out1_b = mpi_alloc( qbits / BITS_PER_MPI_LIMB );
-
- pk.p = sk->p;
- pk.q = sk->q;
- pk.g = sk->g;
- pk.y = sk->y;
- /*mpi_set_bytes( test, qbits, get_random_byte, 0 );*/
- { char *p = get_random_bits( qbits, 0, 0 );
- mpi_set_buffer( test, p, (qbits+7)/8, 0 );
- m_free(p);
- }
-
- sign( out1_a, out1_b, test, sk );
- if( !verify( out1_a, out1_b, test, &pk ) )
- log_fatal("DSA:: sign, verify failed\n");
-
- mpi_free( test );
- mpi_free( out1_a );
- mpi_free( out1_b );
-}
-
-
-
-/****************
- * Generate a DSA key pair with a key of size NBITS
- * Returns: 2 structures filled with all needed values
- * and an array with the n-1 factors of (p-1)
- */
-static void
-generate( DSA_secret_key *sk, unsigned nbits, MPI **ret_factors )
-{
- MPI p; /* the prime */
- MPI q; /* the 160 bit prime factor */
- MPI g; /* the generator */
- MPI y; /* g^x mod p */
- MPI x; /* the secret exponent */
- MPI h, e; /* helper */
- unsigned qbits;
- byte *rndbuf;
-
- assert( nbits >= 512 && nbits <= 1024 );
-
- qbits = 160;
- p = generate_elg_prime( 1, nbits, qbits, NULL, ret_factors );
- /* get q out of factors */
- q = mpi_copy((*ret_factors)[0]);
- if( mpi_get_nbits(q) != qbits )
- BUG();
-
- /* find a generator g (h and e are helpers)*/
- /* e = (p-1)/q */
- e = mpi_alloc( mpi_get_nlimbs(p) );
- mpi_sub_ui( e, p, 1 );
- mpi_fdiv_q( e, e, q );
- g = mpi_alloc( mpi_get_nlimbs(p) );
- h = mpi_alloc_set_ui( 1 ); /* we start with 2 */
- do {
- mpi_add_ui( h, h, 1 );
- /* g = h^e mod p */
- mpi_powm( g, h, e, p );
- } while( !mpi_cmp_ui( g, 1 ) ); /* continue until g != 1 */
-
- /* select a random number which has these properties:
- * 0 < x < q-1
- * This must be a very good random number because this
- * is the secret part. */
- if( DBG_CIPHER )
- log_debug("choosing a random x ");
- assert( qbits >= 160 );
- x = mpi_alloc_secure( mpi_get_nlimbs(q) );
- mpi_sub_ui( h, q, 1 ); /* put q-1 into h */
- rndbuf = NULL;
- do {
- if( DBG_CIPHER )
- progress('.');
- if( !rndbuf )
- rndbuf = get_random_bits( qbits, 2, 1 );
- else { /* change only some of the higher bits (= 2 bytes)*/
- char *r = get_random_bits( 16, 2, 1 );
- memcpy(rndbuf, r, 16/8 );
- m_free(r);
- }
- mpi_set_buffer( x, rndbuf, (qbits+7)/8, 0 );
- mpi_clear_highbit( x, qbits+1 );
- } while( !( mpi_cmp_ui( x, 0 )>0 && mpi_cmp( x, h )<0 ) );
- m_free(rndbuf);
- mpi_free( e );
- mpi_free( h );
-
- /* y = g^x mod p */
- y = mpi_alloc( mpi_get_nlimbs(p) );
- mpi_powm( y, g, x, p );
-
- if( DBG_CIPHER ) {
- progress('\n');
- log_mpidump("dsa p= ", p );
- log_mpidump("dsa q= ", q );
- log_mpidump("dsa g= ", g );
- log_mpidump("dsa y= ", y );
- log_mpidump("dsa x= ", x );
- }
-
- /* copy the stuff to the key structures */
- sk->p = p;
- sk->q = q;
- sk->g = g;
- sk->y = y;
- sk->x = x;
-
- /* now we can test our keys (this should never fail!) */
- test_keys( sk, qbits );
-}
-
-
-
-/****************
- * Test whether the secret key is valid.
- * Returns: if this is a valid key.
- */
-static int
-check_secret_key( DSA_secret_key *sk )
-{
- int rc;
- MPI y = mpi_alloc( mpi_get_nlimbs(sk->y) );
-
- mpi_powm( y, sk->g, sk->x, sk->p );
- rc = !mpi_cmp( y, sk->y );
- mpi_free( y );
- return rc;
-}
-
-
-
-/****************
- * Make a DSA signature from HASH and put it into r and s.
- */
-
-static void
-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);
-}
-
-
-/****************
- * Returns true if the signature composed from R and S is valid.
- */
-static int
-verify(MPI r, MPI s, MPI hash, DSA_public_key *pkey )
-{
- int rc;
- MPI w, u1, u2, v;
- MPI base[3];
- MPI exp[3];
-
-
- if( !(mpi_cmp_ui( r, 0 ) > 0 && mpi_cmp( r, pkey->q ) < 0) )
- return 0; /* assertion 0 < r < q failed */
- if( !(mpi_cmp_ui( s, 0 ) > 0 && mpi_cmp( s, pkey->q ) < 0) )
- return 0; /* assertion 0 < s < q failed */
-
- w = mpi_alloc( mpi_get_nlimbs(pkey->q) );
- u1 = mpi_alloc( mpi_get_nlimbs(pkey->q) );
- u2 = mpi_alloc( mpi_get_nlimbs(pkey->q) );
- v = mpi_alloc( mpi_get_nlimbs(pkey->p) );
-
- /* w = s^(-1) mod q */
- mpi_invm( w, s, 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 );
-
- /* v = g^u1 * y^u2 mod p mod q */
- base[0] = pkey->g; exp[0] = u1;
- base[1] = pkey->y; exp[1] = u2;
- base[2] = NULL; exp[2] = NULL;
- mpi_mulpowm( v, base, exp, pkey->p );
- mpi_fdiv_r( v, v, pkey->q );
-
- rc = !mpi_cmp( v, r );
-
- mpi_free(w);
- mpi_free(u1);
- mpi_free(u2);
- mpi_free(v);
- return rc;
-}
-
-
-/*********************************************
- ************** interface ******************
- *********************************************/
-
-int
-dsa_generate( int algo, unsigned nbits, MPI *skey, MPI **retfactors )
-{
- DSA_secret_key sk;
-
- if( algo != PUBKEY_ALGO_DSA )
- return G10ERR_PUBKEY_ALGO;
-
- generate( &sk, nbits, retfactors );
- skey[0] = sk.p;
- skey[1] = sk.q;
- skey[2] = sk.g;
- skey[3] = sk.y;
- skey[4] = sk.x;
- return 0;
-}
-
-
-int
-dsa_check_secret_key( int algo, MPI *skey )
-{
- DSA_secret_key sk;
-
- if( algo != PUBKEY_ALGO_DSA )
- return G10ERR_PUBKEY_ALGO;
- if( !skey[0] || !skey[1] || !skey[2] || !skey[3] || !skey[4] )
- return G10ERR_BAD_MPI;
-
- sk.p = skey[0];
- sk.q = skey[1];
- sk.g = skey[2];
- sk.y = skey[3];
- sk.x = skey[4];
- if( !check_secret_key( &sk ) )
- return G10ERR_BAD_SECKEY;
-
- return 0;
-}
-
-
-
-int
-dsa_sign( int algo, MPI *resarr, MPI data, MPI *skey )
-{
- DSA_secret_key sk;
-
- if( algo != PUBKEY_ALGO_DSA )
- return G10ERR_PUBKEY_ALGO;
- if( !data || !skey[0] || !skey[1] || !skey[2] || !skey[3] || !skey[4] )
- return G10ERR_BAD_MPI;
-
- sk.p = skey[0];
- sk.q = skey[1];
- sk.g = skey[2];
- sk.y = skey[3];
- sk.x = skey[4];
- resarr[0] = mpi_alloc( mpi_get_nlimbs( sk.p ) );
- resarr[1] = mpi_alloc( mpi_get_nlimbs( sk.p ) );
- sign( resarr[0], resarr[1], data, &sk );
- return 0;
-}
-
-int
-dsa_verify( int algo, MPI hash, MPI *data, MPI *pkey,
- int (*cmp)(void *, MPI) UNUSED, void *opaquev UNUSED)
-{
- DSA_public_key pk;
-
- if( algo != PUBKEY_ALGO_DSA )
- return G10ERR_PUBKEY_ALGO;
- if( !data[0] || !data[1] || !hash
- || !pkey[0] || !pkey[1] || !pkey[2] || !pkey[3] )
- return G10ERR_BAD_MPI;
-
- pk.p = pkey[0];
- pk.q = pkey[1];
- pk.g = pkey[2];
- pk.y = pkey[3];
- if( !verify( data[0], data[1], hash, &pk ) )
- return G10ERR_BAD_SIGN;
- return 0;
-}
-
-
-
-unsigned
-dsa_get_nbits( int algo, MPI *pkey )
-{
- if( algo != PUBKEY_ALGO_DSA )
- return 0;
- return mpi_get_nbits( pkey[0] );
-}
-
-
-/****************
- * Return some information about the algorithm. We need algo here to
- * distinguish different flavors of the algorithm.
- * Returns: A pointer to string describing the algorithm or NULL if
- * the ALGO is invalid.
- * Usage: Bit 0 set : allows signing
- * 1 set : allows encryption
- */
-const char *
-dsa_get_info( int algo, int *npkey, int *nskey, int *nenc, int *nsig,
- int *use )
-{
- *npkey = 4;
- *nskey = 5;
- *nenc = 0;
- *nsig = 2;
-
- switch( algo ) {
- case PUBKEY_ALGO_DSA: *use = PUBKEY_USAGE_SIG; return "DSA";
- default: *use = 0; return NULL;
- }
-}
-
-
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