/* sum = abs(b1) + abs(b2), i.e., add the magnitudes */
void
mpmagadd(mpint *b1, mpint *b2, mpint *sum)
{
int m, n;
mpint *t;
/* get the sizes right */
if(b2->top > b1->top){
t = b1;
b1 = b2;
b2 = t;
}
n = b1->top;
m = b2->top;
if(n == 0){
mpassign(mpzero, sum);
return;
}
if(m == 0){
mpassign(b1, sum);
return;
}
mpbits(sum, (n+1)*Dbits);
sum->top = n+1;
mpvecadd(b1->p, n, b2->p, m, sum->p);
sum->sign = 1;
mpnorm(sum);
}
ECpoint*
strtoec(ECdomain *dom, char *s, char **rptr, ECpoint *ret)
{
int allocd, o;
mpint *r;
allocd = 0;
if(ret == nil){
allocd = 1;
ret = mallocz(sizeof(*ret), 1);
if(ret == nil)
return nil;
ret->x = mpnew(0);
ret->y = mpnew(0);
}
o = 0;
switch(octet(&s)){
case 0:
ret->inf = 1;
return ret;
case 3:
o = 1;
case 2:
if(halfpt(dom, s, &s, ret->x) == nil)
goto err;
r = mpnew(0);
mpmul(ret->x, ret->x, r);
mpadd(r, dom->a, r);
mpmul(r, ret->x, r);
mpadd(r, dom->b, r);
if(!mpsqrt(r, dom->p, r)){
mpfree(r);
goto err;
}
if((r->p[0] & 1) != o)
mpsub(dom->p, r, r);
mpassign(r, ret->y);
mpfree(r);
if(!ecverify(dom, ret))
goto err;
return ret;
case 4:
if(halfpt(dom, s, &s, ret->x) == nil)
goto err;
if(halfpt(dom, s, &s, ret->y) == nil)
goto err;
if(!ecverify(dom, ret))
goto err;
return ret;
}
err:
if(rptr)
*rptr = s;
if(allocd){
mpfree(ret->x);
mpfree(ret->y);
free(ret);
}
return nil;
}
/*
* this code assumes that a vlong is an integral number of
* mpdigits long.
*/
mpint*
vtomp(vlong v, mpint *b)
{
int s;
uvlong uv;
if(b == nil)
b = mpnew(VLDIGITS*sizeof(mpdigit));
else
mpbits(b, VLDIGITS*sizeof(mpdigit));
mpassign(mpzero, b);
if(v == 0)
return b;
if(v < 0){
b->sign = -1;
uv = -v;
} else
uv = v;
for(s = 0; s < VLDIGITS && uv != 0; s++){
b->p[s] = uv;
uv >>= sizeof(mpdigit)*8;
}
b->top = s;
return b;
}
mpint*
uitomp(uint i, mpint *b)
{
if(b == nil)
b = mpnew(0);
mpassign(mpzero, b);
if(i != 0)
b->top = 1;
*b->p = i;
return b;
}
/*
* this code assumes that a vlong is an integral number of
* mpdigits long.
*/
mpint*
uvtomp(uint64_t v, mpint *b)
{
int s;
if(b == nil)
b = mpnew(VLDIGITS*sizeof(mpdigit));
else
mpbits(b, VLDIGITS*sizeof(mpdigit));
mpassign(mpzero, b);
if(v == 0)
return b;
for(s = 0; s < VLDIGITS && v != 0; s++){
b->p[s] = v;
v >>= sizeof(mpdigit)*8;
}
b->top = s;
return b;
}
/* garners algorithm for converting residue form to linear */
void
crtout(CRTpre *crt, CRTres *res, mpint *x)
{
mpint *u;
int i;
u = mpnew(0);
mpassign(res->r[0], x);
for(i = 1; i < crt->n; i++){
mpsub(res->r[i], x, u);
mpmul(u, crt->c[i], u);
mpmod(u, crt->m[i], u);
mpmul(u, crt->p[i-1], u);
mpadd(x, u, x);
}
mpfree(u);
}
void
mpmul(mpint *b1, mpint *b2, mpint *prod)
{
mpint *oprod;
oprod = nil;
if(prod == b1 || prod == b2){
oprod = prod;
prod = mpnew(0);
}
prod->top = 0;
mpbits(prod, (b1->top+b2->top+1)*Dbits);
mpvecmul(b1->p, b1->top, b2->p, b2->top, prod->p);
prod->top = b1->top+b2->top+1;
prod->sign = b1->sign*b2->sign;
mpnorm(prod);
if(oprod != nil){
mpassign(prod, oprod);
mpfree(prod);
}
}
mpint*
mpfactorial(ulong n)
{
int i;
ulong k;
unsigned cnt;
int max, mmax;
mpdigit p, pp[2];
mpint *r, *s, *stk[31];
cnt = 0;
max = mmax = -1;
p = 1;
r = mpnew(0);
for(k=2; k<=n; k++) {
pp[0] = 0;
pp[1] = 0;
mpvecdigmuladd(&p, 1, (mpdigit)k, pp);
if(pp[1] == 0) /* !overflow */
p = pp[0];
else {
cnt++;
if((cnt & 1) == 0) {
s = stk[max];
mpbits(r, Dbits*(s->top+1+1));
memset(r->p, 0, Dbytes*(s->top+1+1));
mpvecmul(s->p, s->top, &p, 1, r->p);
r->sign = 1;
r->top = s->top+1+1; /* XXX: norm */
mpassign(r, s);
for(i=4; (cnt & (i-1)) == 0; i=i<<1) {
mpmul(stk[max], stk[max-1], r);
mpassign(r, stk[max-1]);
max--;
}
} else {
max++;
if(max > mmax) {
mmax++;
if(max > nelem(stk))
abort();
stk[max] = mpnew(Dbits);
}
stk[max]->top = 1;
stk[max]->p[0] = p;
}
p = (mpdigit)k;
}
}
if(max < 0) {
mpbits(r, Dbits);
r->top = 1;
r->sign = 1;
r->p[0] = p;
} else {
s = stk[max--];
mpbits(r, Dbits*(s->top+1+1));
memset(r->p, 0, Dbytes*(s->top+1+1));
mpvecmul(s->p, s->top, &p, 1, r->p);
r->sign = 1;
r->top = s->top+1+1; /* XXX: norm */
}
while(max >= 0)
mpmul(r, stk[max--], r);
for(max=mmax; max>=0; max--)
mpfree(stk[max]);
mpnorm(r);
return r;
}
static int
mpsqrt(mpint *n, mpint *p, mpint *r)
{
mpint *a, *t, *s, *xp, *xq, *yp, *yq, *zp, *zq, *N;
if(mpleg(n, p) == -1)
return 0;
a = mpnew(0);
t = mpnew(0);
s = mpnew(0);
N = mpnew(0);
xp = mpnew(0);
xq = mpnew(0);
yp = mpnew(0);
yq = mpnew(0);
zp = mpnew(0);
zq = mpnew(0);
for(;;){
for(;;){
mprand(mpsignif(p), genrandom, a);
if(mpcmp(a, mpzero) > 0 && mpcmp(a, p) < 0)
break;
}
mpmul(a, a, t);
mpsub(t, n, t);
mpmod(t, p, t);
if(mpleg(t, p) == -1)
break;
}
mpadd(p, mpone, N);
mpright(N, 1, N);
mpmul(a, a, t);
mpsub(t, n, t);
mpassign(a, xp);
uitomp(1, xq);
uitomp(1, yp);
uitomp(0, yq);
while(mpcmp(N, mpzero) != 0){
if(N->p[0] & 1){
mpmul(xp, yp, zp);
mpmul(xq, yq, zq);
mpmul(zq, t, zq);
mpadd(zp, zq, zp);
mpmod(zp, p, zp);
mpmul(xp, yq, zq);
mpmul(xq, yp, s);
mpadd(zq, s, zq);
mpmod(zq, p, yq);
mpassign(zp, yp);
}
mpmul(xp, xp, zp);
mpmul(xq, xq, zq);
mpmul(zq, t, zq);
mpadd(zp, zq, zp);
mpmod(zp, p, zp);
mpmul(xp, xq, zq);
mpadd(zq, zq, zq);
mpmod(zq, p, xq);
mpassign(zp, xp);
mpright(N, 1, N);
}
if(mpcmp(yq, mpzero) != 0)
abort();
mpassign(yp, r);
mpfree(a);
mpfree(t);
mpfree(s);
mpfree(N);
mpfree(xp);
mpfree(xq);
mpfree(yp);
mpfree(yq);
mpfree(zp);
mpfree(zq);
return 1;
}
void
ecadd(ECdomain *dom, ECpoint *a, ECpoint *b, ECpoint *s)
{
mpint *l, *k, *sx, *sy;
if(a->inf && b->inf){
s->inf = 1;
return;
}
if(a->inf){
ecassign(dom, b, s);
return;
}
if(b->inf){
ecassign(dom, a, s);
return;
}
if(mpcmp(a->x, b->x) == 0 && (mpcmp(a->y, mpzero) == 0 || mpcmp(a->y, b->y) != 0)){
s->inf = 1;
return;
}
l = mpnew(0);
k = mpnew(0);
sx = mpnew(0);
sy = mpnew(0);
if(mpcmp(a->x, b->x) == 0 && mpcmp(a->y, b->y) == 0){
mpadd(mpone, mptwo, k);
mpmul(a->x, a->x, l);
mpmul(l, k, l);
mpadd(l, dom->a, l);
mpleft(a->y, 1, k);
mpmod(k, dom->p, k);
mpinvert(k, dom->p, k);
mpmul(k, l, l);
mpmod(l, dom->p, l);
mpleft(a->x, 1, k);
mpmul(l, l, sx);
mpsub(sx, k, sx);
mpmod(sx, dom->p, sx);
mpsub(a->x, sx, sy);
mpmul(l, sy, sy);
mpsub(sy, a->y, sy);
mpmod(sy, dom->p, sy);
mpassign(sx, s->x);
mpassign(sy, s->y);
mpfree(sx);
mpfree(sy);
mpfree(l);
mpfree(k);
return;
}
mpsub(b->y, a->y, l);
mpmod(l, dom->p, l);
mpsub(b->x, a->x, k);
mpmod(k, dom->p, k);
mpinvert(k, dom->p, k);
mpmul(k, l, l);
mpmod(l, dom->p, l);
mpmul(l, l, sx);
mpsub(sx, a->x, sx);
mpsub(sx, b->x, sx);
mpmod(sx, dom->p, sx);
mpsub(a->x, sx, sy);
mpmul(sy, l, sy);
mpsub(sy, a->y, sy);
mpmod(sy, dom->p, sy);
mpassign(sx, s->x);
mpassign(sy, s->y);
mpfree(sx);
mpfree(sy);
mpfree(l);
mpfree(k);
}
// extended binary gcd
//
// For a anv b it solves, v = gcd(a,b) and finds x and y s.t.
// ax + by = v
//
// Handbook of Applied Cryptography, Menezes et al, 1997, pg 608.
void
mpextendedgcd(mpint *a, mpint *b, mpint *v, mpint *x, mpint *y)
{
mpint *u, *A, *B, *C, *D;
int g;
if(a->top == 0){
mpassign(b, v);
mpassign(mpone, y);
mpassign(mpzero, x);
return;
}
if(b->top == 0){
mpassign(a, v);
mpassign(mpone, x);
mpassign(mpzero, y);
return;
}
g = 0;
a = mpcopy(a);
b = mpcopy(b);
while(iseven(a) && iseven(b)){
mpright(a, 1, a);
mpright(b, 1, b);
g++;
}
u = mpcopy(a);
mpassign(b, v);
A = mpcopy(mpone);
B = mpcopy(mpzero);
C = mpcopy(mpzero);
D = mpcopy(mpone);
for(;;) {
// print("%B %B %B %B %B %B\n", u, v, A, B, C, D);
while(iseven(u)){
mpright(u, 1, u);
if(!iseven(A) || !iseven(B)) {
mpadd(A, b, A);
mpsub(B, a, B);
}
mpright(A, 1, A);
mpright(B, 1, B);
}
// print("%B %B %B %B %B %B\n", u, v, A, B, C, D);
while(iseven(v)){
mpright(v, 1, v);
if(!iseven(C) || !iseven(D)) {
mpadd(C, b, C);
mpsub(D, a, D);
}
mpright(C, 1, C);
mpright(D, 1, D);
}
// print("%B %B %B %B %B %B\n", u, v, A, B, C, D);
if(mpcmp(u, v) >= 0){
mpsub(u, v, u);
mpsub(A, C, A);
mpsub(B, D, B);
} else {
mpsub(v, u, v);
mpsub(C, A, C);
mpsub(D, B, D);
}
if(u->top == 0)
break;
}
mpassign(C, x);
mpassign(D, y);
mpleft(v, g, v);
mpfree(A);
mpfree(B);
mpfree(C);
mpfree(D);
mpfree(u);
mpfree(a);
mpfree(b);
}
void
mpexp(mpint *b, mpint *e, mpint *m, mpint *res)
{
mpint *t[2];
int tofree;
mpdigit d, bit;
int i, j;
t[0] = mpcopy(b);
t[1] = res;
tofree = 0;
if(res == b){
b = mpcopy(b);
tofree |= Freeb;
}
if(res == e){
e = mpcopy(e);
tofree |= Freee;
}
if(res == m){
m = mpcopy(m);
tofree |= Freem;
}
// skip first bit
i = e->top-1;
d = e->p[i];
for(bit = mpdighi; (bit & d) == 0; bit >>= 1)
;
bit >>= 1;
j = 0;
for(;;){
for(; bit != 0; bit >>= 1){
mpmul(t[j], t[j], t[j^1]);
if(bit & d)
mpmul(t[j^1], b, t[j]);
else
j ^= 1;
if(m != nil && t[j]->top > m->top){
mpmod(t[j], m, t[j^1]);
j ^= 1;
}
}
if(--i < 0)
break;
bit = mpdighi;
d = e->p[i];
}
if(m != nil){
mpmod(t[j], m, t[j^1]);
j ^= 1;
}
if(t[j] == res){
mpfree(t[j^1]);
} else {
mpassign(t[j], res);
mpfree(t[j]);
}
if(tofree){
if(tofree & Freeb)
mpfree(b);
if(tofree & Freee)
mpfree(e);
if(tofree & Freem)
mpfree(m);
}
}
void
mpeuclid(mpint *a, mpint *b, mpint *d, mpint *x, mpint *y)
{
mpint *tmp, *x0, *x1, *x2, *y0, *y1, *y2, *q, *r;
if(a->sign<0 || b->sign<0)
sysfatal("mpeuclid: negative arg");
if(mpcmp(a, b) < 0){
tmp = a;
a = b;
b = tmp;
tmp = x;
x = y;
y = tmp;
}
if(b->top == 0){
mpassign(a, d);
mpassign(mpone, x);
mpassign(mpzero, y);
return;
}
a = mpcopy(a);
b = mpcopy(b);
x0 = mpnew(0);
x1 = mpcopy(mpzero);
x2 = mpcopy(mpone);
y0 = mpnew(0);
y1 = mpcopy(mpone);
y2 = mpcopy(mpzero);
q = mpnew(0);
r = mpnew(0);
while(b->top != 0 && b->sign > 0){
// q = a/b
// r = a mod b
mpdiv(a, b, q, r);
// x0 = x2 - qx1
mpmul(q, x1, x0);
mpsub(x2, x0, x0);
// y0 = y2 - qy1
mpmul(q, y1, y0);
mpsub(y2, y0, y0);
// rotate values
tmp = a;
a = b;
b = r;
r = tmp;
tmp = x2;
x2 = x1;
x1 = x0;
x0 = tmp;
tmp = y2;
y2 = y1;
y1 = y0;
y0 = tmp;
}
mpassign(a, d);
mpassign(x2, x);
mpassign(y2, y);
mpfree(x0);
mpfree(x1);
mpfree(x2);
mpfree(y0);
mpfree(y1);
mpfree(y2);
mpfree(q);
mpfree(r);
mpfree(a);
mpfree(b);
}
void
mpdiv(mpint *dividend, mpint *divisor, mpint *quotient, mpint *remainder)
{
int j, s, vn, sign;
mpdigit qd, *up, *vp, *qp;
mpint *u, *v, *t;
// divide bv zero
if(divisor->top == 0)
sysfatal("mpdiv: divide by zero");
// quick check
if(mpmagcmp(dividend, divisor) < 0){
if(remainder != nil)
mpassign(dividend, remainder);
if(quotient != nil)
mpassign(mpzero, quotient);
return;
}
// D1: shift until divisor, v, has hi bit set (needed to make trial
// divisor accurate)
qd = divisor->p[divisor->top-1];
for(s = 0; (qd & mpdighi) == 0; s++)
qd <<= 1;
u = mpnew((dividend->top+2)*Dbits + s);
if(s == 0 && divisor != quotient && divisor != remainder) {
mpassign(dividend, u);
v = divisor;
} else {
mpleft(dividend, s, u);
v = mpnew(divisor->top*Dbits);
mpleft(divisor, s, v);
}
up = u->p+u->top-1;
vp = v->p+v->top-1;
vn = v->top;
// D1a: make sure high digit of dividend is less than high digit of divisor
if(*up >= *vp){
*++up = 0;
u->top++;
}
// storage for multiplies
t = mpnew(4*Dbits);
qp = nil;
if(quotient != nil){
mpbits(quotient, (u->top - v->top)*Dbits);
quotient->top = u->top - v->top;
qp = quotient->p+quotient->top-1;
}
// D2, D7: loop on length of dividend
for(j = u->top; j > vn; j--){
// D3: calculate trial divisor
mpdigdiv(up-1, *vp, &qd);
// D3a: rule out trial divisors 2 greater than real divisor
if(vn > 1) for(;;){
memset(t->p, 0, 3*Dbytes); // mpvecdigmuladd adds to what's there
mpvecdigmuladd(vp-1, 2, qd, t->p);
if(mpveccmp(t->p, 3, up-2, 3) > 0)
qd--;
else
break;
}
// D4: u -= v*qd << j*Dbits
sign = mpvecdigmulsub(v->p, vn, qd, up-vn);
if(sign < 0){
// D6: trial divisor was too high, add back borrowed
// value and decrease divisor
mpvecadd(up-vn, vn+1, v->p, vn, up-vn);
qd--;
}
// D5: save quotient digit
if(qp != nil)
*qp-- = qd;
// push top of u down one
u->top--;
*up-- = 0;
}
if(qp != nil){
mpnorm(quotient);
if(dividend->sign != divisor->sign)
quotient->sign = -1;
}
if(remainder != nil){
mpright(u, s, remainder); // u is the remainder shifted
remainder->sign = dividend->sign;
}
mpfree(t);
mpfree(u);
if(v != divisor)
mpfree(v);
}
