/* SU= 8 */
void FP12_conj(FP12 *w,FP12 *x)
{
FP12_copy(w,x);
FP4_conj(&(w->a),&(w->a));
FP4_nconj(&(w->b),&(w->b));
FP4_conj(&(w->c),&(w->c));
}
/* XTR xtr_d function */
void FP4_xtr_D(FP4 *r,FP4 *x)
{
FP4 w;
FP4_copy(r,x);
FP4_conj(&w,r);
FP4_add(&w,&w,&w);
FP4_sqr(r,r);
FP4_sub(r,r,&w);
FP4_reduce(r); /* reduce here as multiple calls trigger automatic reductions */
}
/* r=x^n using XTR method on traces of FP12s */
void FP4_xtr_pow(FP4 *r,FP4 *x,BIG n)
{
int i,par,nb;
BIG v;
FP2 w;
FP4 t,a,b,c;
BIG_zero(v); BIG_inc(v,3);
FP2_from_BIG(&w,v);
FP4_from_FP2(&a,&w);
FP4_copy(&b,x);
FP4_xtr_D(&c,x);
BIG_norm(n); par=BIG_parity(n); BIG_copy(v,n); BIG_shr(v,1);
if (par==0) {BIG_dec(v,1); BIG_norm(v);}
nb=BIG_nbits(v);
for (i=nb-1;i>=0;i--)
{
if (!BIG_bit(v,i))
{
FP4_copy(&t,&b);
FP4_conj(x,x);
FP4_conj(&c,&c);
FP4_xtr_A(&b,&a,&b,x,&c);
FP4_conj(x,x);
FP4_xtr_D(&c,&t);
FP4_xtr_D(&a,&a);
}
else
{
FP4_conj(&t,&a);
FP4_xtr_D(&a,&b);
FP4_xtr_A(&b,&c,&b,x,&t);
FP4_xtr_D(&c,&c);
}
}
if (par==0) FP4_copy(r,&c);
else FP4_copy(r,&b);
FP4_reduce(r);
}
/* SU= 600 */
void FP12_usqr(FP12 *w,FP12 *x)
{
FP4 A,B,C,D;
FP4_copy(&A,&(x->a));
FP4_sqr(&(w->a),&(x->a));
FP4_add(&D,&(w->a),&(w->a));
FP4_add(&(w->a),&D,&(w->a));
#if CHUNK<64
FP4_norm(&(w->a));
#endif
FP4_nconj(&A,&A);
FP4_add(&A,&A,&A);
FP4_add(&(w->a),&(w->a),&A);
FP4_sqr(&B,&(x->c));
FP4_times_i(&B);
FP4_add(&D,&B,&B);
FP4_add(&B,&B,&D);
#if CHUNK<64
FP4_norm(&B);
#endif
FP4_sqr(&C,&(x->b));
FP4_add(&D,&C,&C);
FP4_add(&C,&C,&D);
#if CHUNK<64
FP4_norm(&C);
#endif
FP4_conj(&(w->b),&(x->b));
FP4_add(&(w->b),&(w->b),&(w->b));
FP4_nconj(&(w->c),&(x->c));
FP4_add(&(w->c),&(w->c),&(w->c));
FP4_add(&(w->b),&B,&(w->b));
FP4_add(&(w->c),&C,&(w->c));
FP12_reduce(w); /* reduce here as in pow function repeated squarings would trigger multiple reductions */
}
/* r=ck^a.cl^n using XTR double exponentiation method on traces of FP12s. See Stam thesis. */
void FP4_xtr_pow2(FP4 *r,FP4 *ck,FP4 *cl,FP4 *ckml,FP4 *ckm2l,BIG a,BIG b)
{
int i,f2,nb;
BIG d,e,w;
FP4 t,cu,cv,cumv,cum2v;
BIG_norm(a);
BIG_norm(b);
BIG_copy(e,a);
BIG_copy(d,b);
FP4_copy(&cu,ck);
FP4_copy(&cv,cl);
FP4_copy(&cumv,ckml);
FP4_copy(&cum2v,ckm2l);
f2=0;
while (BIG_parity(d)==0 && BIG_parity(e)==0)
{
BIG_shr(d,1);
BIG_shr(e,1);
f2++;
}
while (BIG_comp(d,e)!=0)
{
if (BIG_comp(d,e)>0)
{
BIG_imul(w,e,4); BIG_norm(w);
if (BIG_comp(d,w)<=0)
{
BIG_copy(w,d);
BIG_copy(d,e);
BIG_sub(e,w,e); BIG_norm(e);
FP4_xtr_A(&t,&cu,&cv,&cumv,&cum2v);
FP4_conj(&cum2v,&cumv);
FP4_copy(&cumv,&cv);
FP4_copy(&cv,&cu);
FP4_copy(&cu,&t);
}
else if (BIG_parity(d)==0)
{
BIG_shr(d,1);
FP4_conj(r,&cum2v);
FP4_xtr_A(&t,&cu,&cumv,&cv,r);
FP4_xtr_D(&cum2v,&cumv);
FP4_copy(&cumv,&t);
FP4_xtr_D(&cu,&cu);
}
else if (BIG_parity(e)==1)
{
BIG_sub(d,d,e); BIG_norm(d);
BIG_shr(d,1);
FP4_xtr_A(&t,&cu,&cv,&cumv,&cum2v);
FP4_xtr_D(&cu,&cu);
FP4_xtr_D(&cum2v,&cv);
FP4_conj(&cum2v,&cum2v);
FP4_copy(&cv,&t);
}
else
{
BIG_copy(w,d);
BIG_copy(d,e); BIG_shr(d,1);
BIG_copy(e,w);
FP4_xtr_D(&t,&cumv);
FP4_conj(&cumv,&cum2v);
FP4_conj(&cum2v,&t);
FP4_xtr_D(&t,&cv);
FP4_copy(&cv,&cu);
FP4_copy(&cu,&t);
}
}
if (BIG_comp(d,e)<0)
{
BIG_imul(w,d,4); BIG_norm(w);
if (BIG_comp(e,w)<=0)
{
BIG_sub(e,e,d); BIG_norm(e);
FP4_xtr_A(&t,&cu,&cv,&cumv,&cum2v);
FP4_copy(&cum2v,&cumv);
FP4_copy(&cumv,&cu);
FP4_copy(&cu,&t);
}
else if (BIG_parity(e)==0)
{
BIG_copy(w,d);
BIG_copy(d,e); BIG_shr(d,1);
BIG_copy(e,w);
FP4_xtr_D(&t,&cumv);
FP4_conj(&cumv,&cum2v);
FP4_conj(&cum2v,&t);
FP4_xtr_D(&t,&cv);
FP4_copy(&cv,&cu);
FP4_copy(&cu,&t);
}
else if (BIG_parity(d)==1)
{
BIG_copy(w,e);
BIG_copy(e,d);
BIG_sub(w,w,d); BIG_norm(w);
BIG_copy(d,w); BIG_shr(d,1);
FP4_xtr_A(&t,&cu,&cv,&cumv,&cum2v);
FP4_conj(&cumv,&cumv);
FP4_xtr_D(&cum2v,&cu);
FP4_conj(&cum2v,&cum2v);
FP4_xtr_D(&cu,&cv);
FP4_copy(&cv,&t);
}
else
{
BIG_shr(d,1);
FP4_conj(r,&cum2v);
FP4_xtr_A(&t,&cu,&cumv,&cv,r);
FP4_xtr_D(&cum2v,&cumv);
FP4_copy(&cumv,&t);
FP4_xtr_D(&cu,&cu);
}
}
}
FP4_xtr_A(r,&cu,&cv,&cumv,&cum2v);
for (i=0;i<f2;i++) FP4_xtr_D(r,r);
FP4_xtr_pow(r,r,d);
}
