xfnw/plan9fox
1
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity

libsec: remove affine coordinate point operations from ecc

Browse source 
we now just do point addtion in jacobian coordinate system, and
convert the result to affine when s->z == nil.
This commit is contained in:
cinap_lenrek 2016-04-21 20:41:19 +02:00
parent 2fa4c8ef66
commit 42c4cc75a6
1 changed files with 18 additions and 75 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

93
sys/src/libsec/port/ecc.c
View file

@ -35,8 +35,6 @@ ecassign(ECdomain *dom, ECpoint *a, ECpoint *b)
void
ecadd(ECdomain *dom, ECpoint *a, ECpoint *b, ECpoint *s)
{
mpint *l, *k, *sx, *sy;
if(a->inf && b->inf){
s->inf = 1;
return;
@ -50,81 +48,26 @@ ecadd(ECdomain *dom, ECpoint *a, ECpoint *b, ECpoint *s)
return;
}
if(s->z != nil){
if(a == b)
jacobian_dbl(dom->p, dom->a,
a->x, a->y, a->z != nil ? a->z : mpone,
s->x, s->y, s->z);
else
jacobian_add(dom->p, dom->a,
a->x, a->y, a->z != nil ? a->z : mpone,
b->x, b->y, b->z != nil ? b->z : mpone,
s->x, s->y, s->z);
s->inf = mpcmp(s->z, mpzero) == 0;
if(s->z == nil){
s->z = mpcopy(mpone);
ecadd(dom, a, b, s);
if(!s->inf)
jacobian_affine(dom->p, s->x, s->y, s->z);
mpfree(s->z);
s->z = nil;
return;
}
if(mpcmp(a->x, b->x) == 0 && (mpcmp(a->y, mpzero) == 0 || mpcmp(a->y, b->y) != 0)){
s->inf = 1;
return;
}
s->inf = 0;
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);
if(a == b)
jacobian_dbl(dom->p, dom->a,
a->x, a->y, a->z != nil ? a->z : mpone,
s->x, s->y, s->z);
else
jacobian_add(dom->p, dom->a,
a->x, a->y, a->z != nil ? a->z : mpone,
b->x, b->y, b->z != nil ? b->z : mpone,
s->x, s->y, s->z);
s->inf = mpcmp(s->z, mpzero) == 0;
}
void
@ -173,10 +116,10 @@ ecverify(ECdomain *dom, ECpoint *a)
mpint *p, *q;
int r;
assert(a->z == nil); /* need affine coordinates */
if(a->inf)
return 1;
assert(a->z == nil); /* need affine coordinates */
p = mpnew(0);
q = mpnew(0);
mpmodmul(a->y, a->y, dom->p, p);