int elgv3sign(const mpbarrett* p, const mpbarrett* n, const mpnumber* g, randomGeneratorContext* rgc, const mpnumber* hm, const mpnumber* x, mpnumber* r, mpnumber* s)
{
register size_t size = p->size;
register mpw* temp = (mpw*) malloc((6*size+2)*sizeof(mpw));
if (temp)
{
/* get a random k */
mpbrnd_w(p, rgc, temp, temp+2*size);
/* compute r = g^k mod p */
mpnfree(r);
mpnsize(r, size);
mpbpowmod_w(p, g->size, g->data, size, temp, r->data, temp+2*size);
/* compute u1 = x*r mod n */
mpbmulmod_w(n, x->size, x->data, size, r->data, temp+size, temp+2*size);
/* compute u2 = k*h(m) mod n */
mpbmulmod_w(n, size, temp, hm->size, hm->data, temp, temp+2*size);
/* compute s = u1+u2 mod n */
mpnfree(s);
mpnsize(s, n->size);
mpbaddmod_w(n, size, temp, size, temp+size, s->data, temp+2*size);
free(temp);
return 0;
}
return -1;
}
int dldp_pgoqGenerator_w(dldp_p* dp, randomGeneratorContext* rgc, mpw* wksp)
{
/*
* Randomly determine a generator over the subgroup with order q
*/
register size_t size = dp->p.size;
mpnfree(&dp->g);
mpnsize(&dp->g, size);
while (1)
{
/* get a random value h (stored into g) */
mpbrnd_w(&dp->p, rgc, dp->g.data, wksp);
/* first compute h^r mod p (stored in g) */
mpbpowmod_w(&dp->p, size, dp->g.data, dp->r.size, dp->r.data, dp->g.data, wksp);
if (mpisone(size, dp->g.data))
continue;
return 0;
}
return -1;
}
int elgv1vrfy(const mpbarrett* p, const mpbarrett* n, const mpnumber* g, const mpnumber* hm, const mpnumber* y, const mpnumber* r, const mpnumber* s)
{
register size_t size = p->size;
register mpw* temp;
if (mpz(r->size, r->data))
return 0;
if (mpgex(r->size, r->data, size, p->modl))
return 0;
if (mpz(s->size, s->data))
return 0;
if (mpgex(s->size, s->data, n->size, n->modl))
return 0;
temp = (mpw*) malloc((6*size+2)*sizeof(mpw));
if (temp)
{
register int rc;
/* compute u1 = y^r mod p */
mpbpowmod_w(p, y->size, y->data, r->size, r->data, temp, temp+2*size);
/* compute u2 = r^s mod p */
mpbpowmod_w(p, r->size, r->data, s->size, s->data, temp+size, temp+2*size);
/* compute v1 = u1*u2 mod p */
mpbmulmod_w(p, size, temp, size, temp+size, temp+size, temp+2*size);
/* compute v2 = g^h(m) mod p */
mpbpowmod_w(p, g->size, g->data, hm->size, hm->data, temp, temp+2*size);
rc = mpeq(size, temp, temp+size);
free(temp);
return rc;
}
return 0;
}
void mpbnpowmod(const mpbarrett* b, const mpnumber* x, const mpnumber* pow, mpnumber* y)
{
register size_t size = b->size;
register mpw* temp = (mpw*) malloc((4*size+2) * sizeof(mpw));
mpnfree(y);
mpnsize(y, size);
mpbpowmod_w(b, x->size, x->data, pow->size, pow->data, y->data, temp);
free(temp);
}
/*
* needs workspace of (5*size+2) words
*/
int mppmilraba_w(const mpbarrett* p, const mpw* adata, int s, const mpw* rdata, const mpw* ndata, mpw* wksp)
{
register size_t size = p->size;
register int j = 0;
mpbpowmod_w(p, size, adata, size, rdata, wksp, wksp+size);
while (1)
{
if (mpisone(size, wksp))
return (j == 0);
if (mpeq(size, wksp, ndata))
return 1;
if (++j < s)
mpbsqrmod_w(p, size, wksp, wksp, wksp+size);
else
return 0;
}
}
int elgv1sign(const mpbarrett* p, const mpbarrett* n, const mpnumber* g, randomGeneratorContext* rgc, const mpnumber* hm, const mpnumber* x, mpnumber* r, mpnumber* s)
{
register size_t size = p->size;
register mpw* temp = (mpw*) malloc((8*size+6)*sizeof(mpw));
if (temp)
{
/* get a random k, invertible modulo (p-1) */
mpbrndinv_w(n, rgc, temp, temp+size, temp+2*size);
/* compute r = g^k mod p */
mpnfree(r);
mpnsize(r, size);
mpbpowmod_w(p, g->size, g->data, size, temp, r->data, temp+2*size);
/* compute x*r mod n */
mpbmulmod_w(n, x->size, x->data, r->size, r->data, temp, temp+2*size);
/* compute -(x*r) mod n */
mpneg(size, temp);
mpadd(size, temp, n->modl);
/* compute h(m) - x*r mod n */
mpbaddmod_w(n, hm->size, hm->data, size, temp, temp, temp+2*size);
/* compute s = inv(k)*(h(m) - x*r) mod n */
mpnfree(s);
mpnsize(s, size);
mpbmulmod_w(n, size, temp, size, temp+size, s->data, temp+2*size);
free(temp);
return 0;
}
return -1;
}
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;
/* h(m) shouldn't contain more bits than q */
if (mpbits(hm->size, hm->data) > mpbits(q->size, q->modl))
return rc;
/* check 0 < r < q */
if (mpz(r->size, r->data))
return rc;
if (mpgex(r->size, r->data, qsize, q->modl))
return rc;
/* check 0 < s < q */
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 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 dldp_pgonGenerator_w(dldp_p* dp, randomGeneratorContext* rgc, mpw* wksp)
{
register size_t size = dp->p.size;
mpnfree(&dp->g);
mpnsize(&dp->g, size);
while (1)
{
mpbrnd_w(&dp->p, rgc, dp->g.data, wksp);
if (mpistwo(dp->r.size, dp->r.data))
{
/*
* A little math here: the only element in the group which has order 2 is (p-1);
* the two group elements raised to power two which result in 1 (mod p) are thus (p-1) and 1
*
* mpbrnd_w doesn't return 1 or (p-1), so the test where g^2 mod p = 1 can be safely skipped
*/
/* check g^q mod p*/
mpbpowmod_w(&dp->p, size, dp->g.data, dp->q.size, dp->q.modl, wksp, wksp+size);
if (mpisone(size, wksp))
continue;
}
else
{
/* we can either compute g^r, g^2q and g^(qr/2) or
* we first compute s = r/2, and then compute g^2s, g^2q and g^qs
*
* hence we first compute t = g^s
* then compute t^2 mod p, and test if one
* then compute t^q mod p, and test if one
* then compute (g^q mod p)^2 mod p, and test if one
*/
/* compute s = r/2 */
mpsetx(size, wksp, dp->r.size, dp->r.data);
mpdivtwo(size, wksp);
/* compute t = g^s mod p */
mpbpowmod_w(&dp->p, size, dp->g.data, size, wksp, wksp+size, wksp+2*size);
/* compute t^2 mod p = g^2s mod p = g^r mod p*/
mpbsqrmod_w(&dp->p, size, wksp+size, wksp+size, wksp+2*size);
if (mpisone(size, wksp+size))
continue;
/* compute t^q mod p = g^qs mod p */
mpbpowmod_w(&dp->p, size, wksp, dp->q.size, dp->q.modl, wksp+size, wksp+2*size);
if (mpisone(size, wksp+size))
continue;
/* compute g^2q mod p */
mpbpowmod_w(&dp->p, size, dp->g.data, dp->q.size, dp->q.modl, wksp, wksp+size);
mpbsqrmod_w(&dp->p, size, wksp, wksp+size, wksp+2*size);
if (mpisone(size, wksp+size))
continue;
}
return 0;
}
return -1;
}
