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/*
* Copyright (c) 2001, 2002 Virtual Unlimited B.V.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
/*!\file dsa.c
* \brief Digital Signature Algorithm.
* \ingroup DL_m DL_dsa_m
*/
#include "system.h"
#include "dsa.h"
#include "dldp.h"
#include "debug.h"
int dsasign(const mpbarrett* p, const mpbarrett* q, const mpnumber* g, randomGeneratorContext* rgc, const mpnumber* hm, const mpnumber* x, mpnumber* r, mpnumber* s)
{
register size_t psize = p->size;
register size_t qsize = q->size;
register mpw* ptemp;
register mpw* qtemp;
register mpw* pwksp;
register mpw* qwksp;
register int rc = -1;
ptemp = (mpw*) malloc((5*psize+2)*sizeof(mpw));
if (ptemp == (mpw*) 0)
return rc;
qtemp = (mpw*) malloc((9*qsize+6)*sizeof(mpw));
if (qtemp == (mpw*) 0)
{
free(ptemp);
return rc;
}
pwksp = ptemp+psize;
qwksp = qtemp+3*qsize;
/* allocate r */
mpnfree(r);
mpnsize(r, qsize);
/* get a random k, invertible modulo q; store k @ qtemp, inv(k) @ qtemp+qsize */
mpbrndinv_w(q, rgc, qtemp, qtemp+qsize, qwksp);
/* g^k mod p */
mpbpowmod_w(p, g->size, g->data, qsize, qtemp, ptemp, pwksp);
/* (g^k mod p) mod q - simple modulo */
mpmod(qtemp+2*qsize, psize, ptemp, qsize, q->modl, pwksp);
mpcopy(qsize, r->data, qtemp+psize+qsize);
/* allocate s */
mpnfree(s);
mpnsize(s, qsize);
/* x*r mod q */
mpbmulmod_w(q, x->size, x->data, r->size, r->data, qtemp, qwksp);
/* add h(m) mod q */
mpbaddmod_w(q, qsize, qtemp, hm->size, hm->data, qtemp+2*qsize, qwksp);
/* multiply inv(k) mod q */
mpbmulmod_w(q, qsize, qtemp+qsize, qsize, qtemp+2*qsize, s->data, qwksp);
rc = 0;
free(qtemp);
free(ptemp);
return rc;
}
int dsavrfy(const mpbarrett* p, const mpbarrett* q, const mpnumber* g, const mpnumber* hm, const mpnumber* y, const mpnumber* r, const mpnumber* s)
{
register size_t psize = p->size;
register size_t qsize = q->size;
register mpw* ptemp;
register mpw* qtemp;
register mpw* pwksp;
register mpw* qwksp;
register int rc = 0;
if (mpz(r->size, r->data))
return rc;
if (mpgex(r->size, r->data, qsize, q->modl))
return rc;
if (mpz(s->size, s->data))
return rc;
if (mpgex(s->size, s->data, qsize, q->modl))
return rc;
ptemp = (mpw*) malloc((6*psize+2)*sizeof(mpw));
if (ptemp == (mpw*) 0)
return rc;
qtemp = (mpw*) malloc((8*qsize+6)*sizeof(mpw));
if (qtemp == (mpw*) 0)
{
free(ptemp);
return rc;
}
pwksp = ptemp+2*psize;
qwksp = qtemp+2*qsize;
mpsetx(qsize, qtemp+qsize, s->size, s->data);
/* compute w = inv(s) mod q */
if (mpextgcd_w(qsize, q->modl, qtemp+qsize, qtemp, qwksp))
{
/* compute u1 = h(m)*w mod q */
mpbmulmod_w(q, hm->size, hm->data, qsize, qtemp, qtemp+qsize, qwksp);
/* compute u2 = r*w mod q */
mpbmulmod_w(q, r->size, r->data, qsize, qtemp, qtemp, qwksp);
/* compute g^u1 mod p */
mpbpowmod_w(p, g->size, g->data, qsize, qtemp+qsize, ptemp, pwksp);
/* compute y^u2 mod p */
mpbpowmod_w(p, y->size, y->data, qsize, qtemp, ptemp+psize, pwksp);
/* multiply mod p */
mpbmulmod_w(p, psize, ptemp, psize, ptemp+psize, ptemp, pwksp);
/* modulo q */
mpmod(ptemp+psize, psize, ptemp, qsize, q->modl, pwksp);
rc = mpeqx(r->size, r->data, psize, ptemp+psize);
}
free(qtemp);
free(ptemp);
return rc;
}
int dsaparamMake(dsaparam* dp, randomGeneratorContext* rgc, size_t psize)
{
/* psize must be >= 512 and <= 1024 */
if ((psize < 512) || (psize > 1024))
return -1;
/* psize must be a multiple of 64 */
if ((psize & 0x3f) != 0)
return -1;
return dldp_pgoqMake(dp, rgc, psize, 160, 1);
}
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