/*
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.
*/

/* AMCL Weierstrass elliptic curve functions over FP2 */
/* SU=m, m is Stack Usage */

#include "ecp2_ZZZ.h"

int ECP2_ZZZ_isinf(const ECP2_ZZZ *P)
{
    return (FP2_YYY_iszilch(&(P->x)) & FP2_YYY_iszilch(&(P->z)));
}

/* Set P=Q */
/* SU= 16 */
void ECP2_ZZZ_copy(ECP2_ZZZ *P,const ECP2_ZZZ *Q)
{
    FP2_YYY_copy(&(P->x),&(Q->x));
    FP2_YYY_copy(&(P->y),&(Q->y));
    FP2_YYY_copy(&(P->z),&(Q->z));
}

/* set P to Infinity */
/* SU= 8 */
void ECP2_ZZZ_inf(ECP2_ZZZ *P)
{
    FP2_YYY_zero(&(P->x));
    FP2_YYY_one(&(P->y));
    FP2_YYY_zero(&(P->z));
}

/* Conditional move Q to P dependant on d */
static void ECP2_ZZZ_cmove(ECP2_ZZZ *P,const ECP2_ZZZ *Q,int d)
{
    FP2_YYY_cmove(&(P->x),&(Q->x),d);
    FP2_YYY_cmove(&(P->y),&(Q->y),d);
    FP2_YYY_cmove(&(P->z),&(Q->z),d);
}

/* return 1 if b==c, no branching */
static int teq(sign32 b,sign32 c)
{
    sign32 x=b^c;
    x-=1;  // if x=0, x now -1
    return (x>>31)&1;
}

/* Constant time select from pre-computed table */
static void ECP2_ZZZ_select(ECP2_ZZZ *P,const ECP2_ZZZ W[],sign32 b)
{
    ECP2_ZZZ MP;
    sign32 m=b>>31;
    sign32 babs=(b^m)-m;

    babs=(babs-1)/2;

    ECP2_ZZZ_cmove(P,&W[0],teq(babs,0));  // conditional move
    ECP2_ZZZ_cmove(P,&W[1],teq(babs,1));
    ECP2_ZZZ_cmove(P,&W[2],teq(babs,2));
    ECP2_ZZZ_cmove(P,&W[3],teq(babs,3));
    ECP2_ZZZ_cmove(P,&W[4],teq(babs,4));
    ECP2_ZZZ_cmove(P,&W[5],teq(babs,5));
    ECP2_ZZZ_cmove(P,&W[6],teq(babs,6));
    ECP2_ZZZ_cmove(P,&W[7],teq(babs,7));

    ECP2_ZZZ_copy(&MP,P);
    ECP2_ZZZ_neg(&MP);  // minus P
    ECP2_ZZZ_cmove(P,&MP,m&1);
}

/* return 1 if P==Q, else 0 */
/* SU= 312 */
int ECP2_ZZZ_equals(ECP2_ZZZ *P,ECP2_ZZZ *Q)
{
    FP2_YYY a;
    FP2_YYY b;

    FP2_YYY_mul(&a,&(P->x),&(Q->z));
    FP2_YYY_mul(&b,&(Q->x),&(P->z));
    if (!FP2_YYY_equals(&a,&b)) return 0;

    FP2_YYY_mul(&a,&(P->y),&(Q->z));
    FP2_YYY_mul(&b,&(Q->y),&(P->z));
    if (!FP2_YYY_equals(&a,&b)) return 0;
    return 1;
}

/* Make P affine (so z=1) */
/* SU= 232 */
void ECP2_ZZZ_affine(ECP2_ZZZ *P)
{
    FP2_YYY one;
    FP2_YYY iz;
    if (ECP2_ZZZ_isinf(P)) return;

    FP2_YYY_one(&one);
    if (FP2_YYY_isunity(&(P->z)))
    {
        FP2_YYY_reduce(&(P->x));
        FP2_YYY_reduce(&(P->y));
        return;
    }

    FP2_YYY_inv(&iz,&(P->z));
    FP2_YYY_mul(&(P->x),&(P->x),&iz);
    FP2_YYY_mul(&(P->y),&(P->y),&iz);

    FP2_YYY_reduce(&(P->x));
    FP2_YYY_reduce(&(P->y));
    FP2_YYY_copy(&(P->z),&one);
}

/* extract x, y from point P */
/* SU= 16 */
int ECP2_ZZZ_get(FP2_YYY *x,FP2_YYY *y,const ECP2_ZZZ *P)
{
    ECP2_ZZZ W;
    ECP2_ZZZ_copy(&W,P);
    ECP2_ZZZ_affine(&W);
    if (ECP2_ZZZ_isinf(&W)) return -1;
    FP2_YYY_copy(y,&(W.y));
    FP2_YYY_copy(x,&(W.x));
    return 0;
}

/* SU= 152 */
/* Output point P */
void ECP2_ZZZ_output(const ECP2_ZZZ *P)
{
    FP2_YYY x;
    FP2_YYY y;
    if (ECP2_ZZZ_isinf(P))
    {
        printf("Infinity\n");
        return;
    }
    ECP2_ZZZ_get(&x,&y,P);
    printf("(");
    FP2_YYY_output(&x);
    printf(",");
    FP2_YYY_output(&y);
    printf(")\n");
}

/* SU= 232 */
void ECP2_ZZZ_outputxyz(const ECP2_ZZZ *P)
{
    ECP2_ZZZ Q;
    if (ECP2_ZZZ_isinf(P))
    {
        printf("Infinity\n");
        return;
    }
    ECP2_ZZZ_copy(&Q,P);
    printf("(");
    FP2_YYY_output(&(Q.x));
    printf(",");
    FP2_YYY_output(&(Q.y));
    printf(",");
    FP2_YYY_output(&(Q.z));
    printf(")\n");
}

/* SU= 168 */
/* Convert Q to octet string */
void ECP2_ZZZ_toOctet(octet *W,const ECP2_ZZZ *Q)
{
    BIG_XXX b;
    FP2_YYY qx;
    FP2_YYY qy;
    ECP2_ZZZ_get(&qx,&qy,Q);

    FP_YYY_redc(b,&(qx.a));
    BIG_XXX_toBytes(&(W->val[0]),b);
    FP_YYY_redc(b,&(qx.b));
    BIG_XXX_toBytes(&(W->val[MODBYTES_XXX]),b);
    FP_YYY_redc(b,&(qy.a));
    BIG_XXX_toBytes(&(W->val[2*MODBYTES_XXX]),b);
    FP_YYY_redc(b,&(qy.b));
    BIG_XXX_toBytes(&(W->val[3*MODBYTES_XXX]),b);

    W->len=4*MODBYTES_XXX;

}

/* SU= 176 */
/* restore Q from octet string */
int ECP2_ZZZ_fromOctet(ECP2_ZZZ *Q,const octet *W)
{
    BIG_XXX b;
    FP2_YYY qx;
    FP2_YYY qy;
    BIG_XXX_fromBytes(b,&(W->val[0]));
    FP_YYY_nres(&(qx.a),b);
    BIG_XXX_fromBytes(b,&(W->val[MODBYTES_XXX]));
    FP_YYY_nres(&(qx.b),b);
    BIG_XXX_fromBytes(b,&(W->val[2*MODBYTES_XXX]));
    FP_YYY_nres(&(qy.a),b);
    BIG_XXX_fromBytes(b,&(W->val[3*MODBYTES_XXX]));
    FP_YYY_nres(&(qy.b),b);

    if (ECP2_ZZZ_set(Q,&qx,&qy)) return 1;
    return 0;
}

/* SU= 128 */
/* Calculate RHS of twisted curve equation x^3+B/i or x^3+Bi*/
void ECP2_ZZZ_rhs(FP2_YYY *rhs,const FP2_YYY *x)
{
    /* calculate RHS of elliptic curve equation */
    FP2_YYY t;
    BIG_XXX b;
    FP2_YYY_sqr(&t,x);

    FP2_YYY_mul(rhs,&t,x);

    /* Assuming CURVE_A=0 */

    BIG_XXX_rcopy(b,CURVE_B_ZZZ);

    FP2_YYY_from_BIG(&t,b);

#if SEXTIC_TWIST_ZZZ == D_TYPE
    FP2_YYY_div_ip(&t);   /* IMPORTANT - here we use the correct SEXTIC twist of the curve */
#endif

#if SEXTIC_TWIST_ZZZ == M_TYPE
    FP2_YYY_norm(&t);
    FP2_YYY_mul_ip(&t);   /* IMPORTANT - here we use the correct SEXTIC twist of the curve */
    FP2_YYY_norm(&t);

#endif


    FP2_YYY_add(rhs,&t,rhs);
    FP2_YYY_reduce(rhs);
}

/* SU= 232 */
int ECP2_ZZZ_set(ECP2_ZZZ *P,const FP2_YYY *x,const FP2_YYY *y)
{
    FP2_YYY rhs;
    FP2_YYY y2;

    FP2_YYY_sqr(&y2,y);
    ECP2_ZZZ_rhs(&rhs,x);

    if (!FP2_YYY_equals(&y2,&rhs))
    {
        ECP2_ZZZ_inf(P);
        return 0;
    }

    FP2_YYY_copy(&(P->x),x);
    FP2_YYY_copy(&(P->y),y);

    FP2_YYY_one(&(P->z));
    return 1;
}
/* `Set P=(x,y). Return 1 if (x,.) is on the curve, else return 0` */
/* SU= 232 */
int ECP2_ZZZ_setx(ECP2_ZZZ *P,const FP2_YYY *x)
{
    FP2_YYY y;
    ECP2_ZZZ_rhs(&y,x);

    if (!FP2_YYY_sqrt(&y,&y))
    {
        ECP2_ZZZ_inf(P);
        return 0;
    }

    FP2_YYY_copy(&(P->x),x);
    FP2_YYY_copy(&(P->y),&y);
    FP2_YYY_one(&(P->z));
    return 1;
}

/* Set P=-P */
/* SU= 8 */
void ECP2_ZZZ_neg(ECP2_ZZZ *P)
{
    FP2_YYY_norm(&(P->y));
    FP2_YYY_neg(&(P->y),&(P->y));
    FP2_YYY_norm(&(P->y));
}

/* R+=R */
/* return -1 for Infinity, 0 for addition, 1 for doubling */
/* SU= 448 */
int ECP2_ZZZ_dbl(ECP2_ZZZ *P)
{
    FP2_YYY t0;
    FP2_YYY t1;
    FP2_YYY t2;
    FP2_YYY iy;
    FP2_YYY x3;
    FP2_YYY y3;

    FP2_YYY_copy(&iy,&(P->y));		                //FP2 iy=new FP2(y)
#if SEXTIC_TWIST_ZZZ==D_TYPE
    FP2_YYY_mul_ip(&iy);			                //iy.mul_ip()
    FP2_YYY_norm(&iy);				                //iy.norm()
#endif
    FP2_YYY_sqr(&t0,&(P->y));			            //t0.sqr()
#if SEXTIC_TWIST_ZZZ==D_TYPE
    FP2_YYY_mul_ip(&t0);			                //t0.mul_ip()
#endif
    FP2_YYY_mul(&t1,&iy,&(P->z));	                //t1.mul(z)
    FP2_YYY_sqr(&t2,&(P->z));			        	//t2.sqr()

    FP2_YYY_add(&(P->z),&t0,&t0);	                //z.add(t0)
    FP2_YYY_norm(&(P->z));				            //z.norm()
    FP2_YYY_add(&(P->z),&(P->z),&(P->z));	        //z.add(z)
    FP2_YYY_add(&(P->z),&(P->z),&(P->z));	        //z.add(z)
    FP2_YYY_norm(&(P->z));			                //z.norm()

    FP2_YYY_imul(&t2,&t2,3*CURVE_B_I_ZZZ);	        //t2.imul(3*ROM.CURVE_B_I)
#if SEXTIC_TWIST_ZZZ==M_TYPE
    FP2_YYY_mul_ip(&t2);
    FP2_YYY_norm(&t2);
#endif

    FP2_YYY_mul(&x3,&t2,&(P->z));	                //x3.mul(z)

    FP2_YYY_add(&y3,&t0,&t2);		                //y3.add(t2)
    FP2_YYY_norm(&y3);				                //y3.norm()
    FP2_YYY_mul(&(P->z),&(P->z),&t1);	            //z.mul(t1)

    FP2_YYY_add(&t1,&t2,&t2);	                	//t1.add(t2)
    FP2_YYY_add(&t2,&t2,&t1);	                	//t2.add(t1)
    FP2_YYY_norm(&t2);			                	//t2.norm()
    FP2_YYY_sub(&t0,&t0,&t2);		                //t0.sub(t2)
    FP2_YYY_norm(&t0);				                //t0.norm()         //y^2-9bz^2
    FP2_YYY_mul(&y3,&y3,&t0);		                //y3.mul(t0)
    FP2_YYY_add(&(P->y),&y3,&x3);		            //y3.add(x3)        //(y^2+3z*2)(y^2-9z^2)+3b.z^2.8y^2
    FP2_YYY_mul(&t1,&(P->x),&iy);		            //t1.mul(iy)
    FP2_YYY_norm(&t0);			                    //x.norm()
    FP2_YYY_mul(&(P->x),&t0,&t1);	                //x.mul(t1)
    FP2_YYY_add(&(P->x),&(P->x),&(P->x));	        //x.add(x)          //(y^2-9bz^2)xy2

    FP2_YYY_norm(&(P->x));			                //x.norm()
    FP2_YYY_norm(&(P->y));			                //y.norm()

    return 1;
}

/* Set P+=Q */
/* SU= 400 */
int ECP2_ZZZ_add(ECP2_ZZZ *P,const ECP2_ZZZ *Q)
{
    FP2_YYY t0;
    FP2_YYY t1;
    FP2_YYY t2;
    FP2_YYY t3;
    FP2_YYY t4;
    FP2_YYY x3;
    FP2_YYY y3;
    FP2_YYY z3;
    int b3=3*CURVE_B_I_ZZZ;

    FP2_YYY_mul(&t0,&(P->x),&(Q->x));	            //t0.mul(Q.x)       // x.Q.x
    FP2_YYY_mul(&t1,&(P->y),&(Q->y));	            //t1.mul(Q.y)		// y.Q.y

    FP2_YYY_mul(&t2,&(P->z),&(Q->z));	            //t2.mul(Q.z)
    FP2_YYY_add(&t3,&(P->x),&(P->y));	            //t3.add(y)
    FP2_YYY_norm(&t3);				                //t3.norm()         //t3=X1+Y1

    FP2_YYY_add(&t4,&(Q->x),&(Q->y));	            //t4.add(Q.y)
    FP2_YYY_norm(&t4);				                //t4.norm()			//t4=X2+Y2
    FP2_YYY_mul(&t3,&t3,&t4);		                //t3.mul(t4)	    //t3=(X1+Y1)(X2+Y2)
    FP2_YYY_add(&t4,&t0,&t1);		                //t4.add(t1)		//t4=X1.X2+Y1.Y2

    FP2_YYY_sub(&t3,&t3,&t4);		                //t3.sub(t4)
    FP2_YYY_norm(&t3);				                //t3.norm()
#if SEXTIC_TWIST_ZZZ==D_TYPE
    FP2_YYY_mul_ip(&t3);			                //t3.mul_ip()
    FP2_YYY_norm(&t3);				                //t3.norm()         //t3=(X1+Y1)(X2+Y2)-(X1.X2+Y1.Y2) = X1.Y2+X2.Y1
#endif
    FP2_YYY_add(&t4,&(P->y),&(P->z));	            //t4.add(z)
    FP2_YYY_norm(&t4);				                //t4.norm()			//t4=Y1+Z1
    FP2_YYY_add(&x3,&(Q->y),&(Q->z));	            //x3.add(Q.z)
    FP2_YYY_norm(&x3);				                //x3.norm()			//x3=Y2+Z2

    FP2_YYY_mul(&t4,&t4,&x3);		                //t4.mul(x3)		//t4=(Y1+Z1)(Y2+Z2)
    FP2_YYY_add(&x3,&t1,&t2);		                //x3.add(t2)		//X3=Y1.Y2+Z1.Z2

    FP2_YYY_sub(&t4,&t4,&x3);		                //t4.sub(x3)
    FP2_YYY_norm(&t4);				                //t4.norm()
#if SEXTIC_TWIST_ZZZ==D_TYPE
    FP2_YYY_mul_ip(&t4);		                	//t4.mul_ip()
    FP2_YYY_norm(&t4);			                	//t4.norm()         //t4=(Y1+Z1)(Y2+Z2) - (Y1.Y2+Z1.Z2) = Y1.Z2+Y2.Z1
#endif
    FP2_YYY_add(&x3,&(P->x),&(P->z));	            //x3.add(z)
    FP2_YYY_norm(&x3);				                //x3.norm()	        // x3=X1+Z1
    FP2_YYY_add(&y3,&(Q->x),&(Q->z));	            //y3.add(Q.z)
    FP2_YYY_norm(&y3);				                //y3.norm()			// y3=X2+Z2
    FP2_YYY_mul(&x3,&x3,&y3);		                //x3.mul(y3)		// x3=(X1+Z1)(X2+Z2)
    FP2_YYY_add(&y3,&t0,&t2);		                //y3.add(t2)		// y3=X1.X2+Z1+Z2
    FP2_YYY_sub(&y3,&x3,&y3);		                //y3.rsub(x3)
    FP2_YYY_norm(&y3);			                	//y3.norm()			// y3=(X1+Z1)(X2+Z2) - (X1.X2+Z1.Z2) = X1.Z2+X2.Z1
#if SEXTIC_TWIST_ZZZ==D_TYPE
    FP2_YYY_mul_ip(&t0);		                   	//t0.mul_ip()
    FP2_YYY_norm(&t0);		                		//t0.norm()         // x.Q.x
    FP2_YYY_mul_ip(&t1);		                	//t1.mul_ip()
    FP2_YYY_norm(&t1);			                	//t1.norm()         // y.Q.y
#endif
    FP2_YYY_add(&x3,&t0,&t0);	                	//x3.add(t0)
    FP2_YYY_add(&t0,&t0,&x3);	                	//t0.add(x3)
    FP2_YYY_norm(&t0);			                	//t0.norm()
    FP2_YYY_imul(&t2,&t2,b3);		                //t2.imul(b)
#if SEXTIC_TWIST_ZZZ==M_TYPE
    FP2_YYY_mul_ip(&t2);
    FP2_YYY_norm(&t2);
#endif
    FP2_YYY_add(&z3,&t1,&t2);		                //z3.add(t2)
    FP2_YYY_norm(&z3);			                	//z3.norm()
    FP2_YYY_sub(&t1,&t1,&t2);	                	//t1.sub(t2)
    FP2_YYY_norm(&t1);			                	//t1.norm()
    FP2_YYY_imul(&y3,&y3,b3);		                //y3.imul(b)
#if SEXTIC_TWIST_ZZZ==M_TYPE
    FP2_YYY_mul_ip(&y3);
    FP2_YYY_norm(&y3);
#endif
    FP2_YYY_mul(&x3,&y3,&t4);		                //x3.mul(t4)
    FP2_YYY_mul(&t2,&t3,&t1);		                //t2.mul(t1)
    FP2_YYY_sub(&(P->x),&t2,&x3);	            	//x3.rsub(t2)
    FP2_YYY_mul(&y3,&y3,&t0);		                //y3.mul(t0)
    FP2_YYY_mul(&t1,&t1,&z3);		                //t1.mul(z3)
    FP2_YYY_add(&(P->y),&y3,&t1);	               	//y3.add(t1)
    FP2_YYY_mul(&t0,&t0,&t3);		                //t0.mul(t3)
    FP2_YYY_mul(&z3,&z3,&t4);		                //z3.mul(t4)
    FP2_YYY_add(&(P->z),&z3,&t0);	            	//z3.add(t0)

    FP2_YYY_norm(&(P->x));			                //x.norm()
    FP2_YYY_norm(&(P->y));			                //y.norm()
    FP2_YYY_norm(&(P->z));			                //z.norm()

    return 0;
}

/* Set P-=Q */
/* SU= 16 */
void ECP2_ZZZ_sub(ECP2_ZZZ *P,const ECP2_ZZZ *Q)
{
    ECP2_ZZZ NQ;
    ECP2_ZZZ_copy(&NQ,Q);
    ECP2_ZZZ_neg(&NQ);
    ECP2_ZZZ_add(P,&NQ);
}

/* P*=e */
/* SU= 280 */
void ECP2_ZZZ_mul(ECP2_ZZZ *P,const BIG_XXX e)
{
    /* fixed size windows */
    int i;
    int nb;
    int s;
    int ns;
    BIG_XXX mt;
    BIG_XXX t;
    ECP2_ZZZ Q;
    ECP2_ZZZ W[8];
    ECP2_ZZZ C;
    sign8 w[1+(NLEN_XXX*BASEBITS_XXX+3)/4];

    if (ECP2_ZZZ_isinf(P)) return;

    /* precompute table */

    ECP2_ZZZ_copy(&Q,P);
    ECP2_ZZZ_dbl(&Q);
    ECP2_ZZZ_copy(&W[0],P);

    for (i=1; i<8; i++)
    {
        ECP2_ZZZ_copy(&W[i],&W[i-1]);
        ECP2_ZZZ_add(&W[i],&Q);
    }

    /* make exponent odd - add 2P if even, P if odd */
    BIG_XXX_copy(t,e);
    s=BIG_XXX_parity(t);
    BIG_XXX_inc(t,1);
    BIG_XXX_norm(t);
    ns=BIG_XXX_parity(t);
    BIG_XXX_copy(mt,t);
    BIG_XXX_inc(mt,1);
    BIG_XXX_norm(mt);
    BIG_XXX_cmove(t,mt,s);
    ECP2_ZZZ_cmove(&Q,P,ns);
    ECP2_ZZZ_copy(&C,&Q);

    nb=1+(BIGBITS_XXX+3)/4;

    /* convert exponent to signed 4-bit window */
    for (i=0; i<nb; i++)
    {
        w[i]=(signed char)(BIG_XXX_lastbits(t,5)-16);
        BIG_XXX_dec(t,w[i]);
        BIG_XXX_norm(t);
        BIG_XXX_fshr(t,4);
    }
    w[nb]=(signed char)BIG_XXX_lastbits(t,5);

    ECP2_ZZZ_copy(P,&W[(w[nb]-1)/2]);
    for (i=nb-1; i>=0; i--)
    {
        ECP2_ZZZ_select(&Q,W,w[i]);
        ECP2_ZZZ_dbl(P);
        ECP2_ZZZ_dbl(P);
        ECP2_ZZZ_dbl(P);
        ECP2_ZZZ_dbl(P);
        ECP2_ZZZ_add(P,&Q);
    }
    ECP2_ZZZ_sub(P,&C); /* apply correction */
    ECP2_ZZZ_affine(P);
}

/* Calculates q.P using Frobenius constant X */
/* SU= 96 */
void ECP2_ZZZ_frob(ECP2_ZZZ *P,FP2_YYY *X)
{
    FP2_YYY X2;

    FP2_YYY_sqr(&X2,X);
    FP2_YYY_conj(&(P->x),&(P->x));
    FP2_YYY_conj(&(P->y),&(P->y));
    FP2_YYY_conj(&(P->z),&(P->z));
    FP2_YYY_reduce(&(P->z));

    FP2_YYY_mul(&(P->x),&X2,&(P->x));
    FP2_YYY_mul(&(P->y),&X2,&(P->y));
    FP2_YYY_mul(&(P->y),X,&(P->y));

}


// Bos & Costello https://eprint.iacr.org/2013/458.pdf
// Faz-Hernandez & Longa & Sanchez  https://eprint.iacr.org/2013/158.pdf
// Side channel attack secure

void ECP2_ZZZ_mul4(ECP2_ZZZ *P,const ECP2_ZZZ Q[4],const BIG_XXX u[4])
{
    int i;
    int k;
    int nb;
    int pb;
    int bt;
    ECP2_ZZZ T[8];
    ECP2_ZZZ W;
    BIG_XXX t[4];
    BIG_XXX mt;
    sign8 w[NLEN_XXX*BASEBITS_XXX+1] = {0};
    sign8 s[NLEN_XXX*BASEBITS_XXX+1];

    for (i=0; i<4; i++)
    {
        BIG_XXX_copy(t[i],u[i]);
    }

// Precomputed table
    ECP2_ZZZ_copy(&T[0],&Q[0]); // Q[0]
    ECP2_ZZZ_copy(&T[1],&T[0]);
    ECP2_ZZZ_add(&T[1],&Q[1]);	// Q[0]+Q[1]
    ECP2_ZZZ_copy(&T[2],&T[0]);
    ECP2_ZZZ_add(&T[2],&Q[2]);	// Q[0]+Q[2]
    ECP2_ZZZ_copy(&T[3],&T[1]);
    ECP2_ZZZ_add(&T[3],&Q[2]);	// Q[0]+Q[1]+Q[2]
    ECP2_ZZZ_copy(&T[4],&T[0]);
    ECP2_ZZZ_add(&T[4],&Q[3]);  // Q[0]+Q[3]
    ECP2_ZZZ_copy(&T[5],&T[1]);
    ECP2_ZZZ_add(&T[5],&Q[3]);	// Q[0]+Q[1]+Q[3]
    ECP2_ZZZ_copy(&T[6],&T[2]);
    ECP2_ZZZ_add(&T[6],&Q[3]);	// Q[0]+Q[2]+Q[3]
    ECP2_ZZZ_copy(&T[7],&T[3]);
    ECP2_ZZZ_add(&T[7],&Q[3]);	// Q[0]+Q[1]+Q[2]+Q[3]

// Make it odd
    pb=1-BIG_XXX_parity(t[0]);
    BIG_XXX_inc(t[0],pb);
    BIG_XXX_norm(t[0]);

// Number of bits
    BIG_XXX_zero(mt);
    for (i=0; i<4; i++)
    {
        BIG_XXX_or(mt,mt,t[i]);
    }
    nb=1+BIGBITS_XXX;

// Sign pivot
    s[nb-1]=1;
    for (i=0; i<nb-1; i++)
    {
        BIG_XXX_fshr(t[0],1);
        s[i]=(signed char)(2*BIG_XXX_parity(t[0])-1);
    }

// Recoded exponent
    for (i=0; i<nb; i++)
    {
        k=1;
        for (int j=1; j<4; j++)
        {
            bt=s[i]*BIG_XXX_parity(t[j]);
            BIG_XXX_fshr(t[j],1);

            BIG_XXX_dec(t[j],(bt>>1));
            BIG_XXX_norm(t[j]);
            w[i]+=bt*k;
            k*=2;
        }
    }

// Main loop
    ECP2_ZZZ_select(P,T,2*w[nb-1]+1);
    for (i=nb-2; i>=0; i--)
    {
        ECP2_ZZZ_select(&W,T,2*w[i]+s[i]);
        ECP2_ZZZ_dbl(P);
        ECP2_ZZZ_add(P,&W);
    }

// apply correction
    ECP2_ZZZ_copy(&W,P);
    ECP2_ZZZ_sub(&W,&Q[0]);
    ECP2_ZZZ_cmove(P,&W,pb);

    ECP2_ZZZ_affine(P);

    // zeroization
    for (i=0; i<4; i++)
        BIG_XXX_zero(t[i]);
}

/* Map to hash value to point on G2 from random BIG */
void ECP2_ZZZ_mapit(ECP2_ZZZ *Q,const octet *W)
{
    BIG_XXX q;
    BIG_XXX one;
    BIG_XXX Fx;
    BIG_XXX Fy;
    BIG_XXX x;
    BIG_XXX hv;
    FP2_YYY X;
#if (PAIRING_FRIENDLY_ZZZ == BN)
    ECP2_ZZZ T;
    ECP2_ZZZ K;
#elif (PAIRING_FRIENDLY_ZZZ == BLS)
    ECP2_ZZZ xQ;
    ECP2_ZZZ x2Q;
#endif
    BIG_XXX_fromBytes(hv,W->val);
    BIG_XXX_rcopy(q,Modulus_ZZZ);
    BIG_XXX_one(one);
    BIG_XXX_mod(hv,q);

    for (;;)
    {
        FP2_YYY_from_BIGs(&X,one,hv);
        if (ECP2_ZZZ_setx(Q,&X)) break;
        BIG_XXX_inc(hv,1);
        BIG_XXX_norm(hv);
    }

    BIG_XXX_rcopy(Fx,Fra_YYY);
    BIG_XXX_rcopy(Fy,Frb_YYY);
    FP2_YYY_from_BIGs(&X,Fx,Fy);

#if SEXTIC_TWIST_ZZZ==M_TYPE
    FP2_YYY_inv(&X,&X);
    FP2_YYY_norm(&X);
#endif

    BIG_XXX_rcopy(x,CURVE_Bnx_ZZZ);

#if (PAIRING_FRIENDLY_ZZZ == BN)

    /* Faster Hashing to G2 - Fuentes-Castaneda, Knapp and Rodriguez-Henriquez */
    /* Q -> xQ + F(3xQ) + F(F(xQ)) + F(F(F(Q))). */
    ECP2_ZZZ_copy(&T,Q);
    ECP2_ZZZ_mul(&T,x);
#if SIGN_OF_X_ZZZ==NEGATIVEX
    ECP2_ZZZ_neg(&T);   // our x is negative
#endif
    ECP2_ZZZ_copy(&K,&T);
    ECP2_ZZZ_dbl(&K);
    ECP2_ZZZ_add(&K,&T);

    ECP2_ZZZ_frob(&K,&X);
    ECP2_ZZZ_frob(Q,&X);
    ECP2_ZZZ_frob(Q,&X);
    ECP2_ZZZ_frob(Q,&X);
    ECP2_ZZZ_add(Q,&T);
    ECP2_ZZZ_add(Q,&K);
    ECP2_ZZZ_frob(&T,&X);
    ECP2_ZZZ_frob(&T,&X);
    ECP2_ZZZ_add(Q,&T);
    ECP2_ZZZ_affine(Q);

#elif (PAIRING_FRIENDLY_ZZZ == BLS)

    /* Efficient hash maps to G2 on BLS curves - Budroni, Pintore */
    /* Q -> x2Q -xQ -Q +F(xQ -Q) +F(F(2Q)) */

    ECP2_ZZZ_copy(&xQ,Q);
    ECP2_ZZZ_mul(&xQ,x);

    ECP2_ZZZ_copy(&x2Q,&xQ);
    ECP2_ZZZ_mul(&x2Q,x);

#if SIGN_OF_X_ZZZ==NEGATIVEX
    ECP2_ZZZ_neg(&xQ);
#endif

    ECP2_ZZZ_sub(&x2Q,&xQ);
    ECP2_ZZZ_sub(&x2Q,Q);

    ECP2_ZZZ_sub(&xQ,Q);
    ECP2_ZZZ_frob(&xQ,&X);

    ECP2_ZZZ_dbl(Q);
    ECP2_ZZZ_frob(Q,&X);
    ECP2_ZZZ_frob(Q,&X);

    ECP2_ZZZ_add(Q,&x2Q);
    ECP2_ZZZ_add(Q,&xQ);

    ECP2_ZZZ_affine(Q);

#endif
}

void ECP2_ZZZ_generator(ECP2_ZZZ *G)
{
    FP2_YYY wx;
    FP2_YYY wy;

    FP_YYY_rcopy(&(wx.a),CURVE_Pxa_ZZZ);
    FP_YYY_rcopy(&(wx.b),CURVE_Pxb_ZZZ);
    FP_YYY_rcopy(&(wy.a),CURVE_Pya_ZZZ);
    FP_YYY_rcopy(&(wy.b),CURVE_Pyb_ZZZ);

    ECP2_ZZZ_set(G,&wx,&wy);
}


// The following functions are specific for hashing to curve on BLS12-381
#if (PAIRING_FRIENDLY_ZZZ == BLS && CURVE_SECURITY_ZZZ == 128)

static int sgn0_fp2(const FP2_YYY y)
{
    int sign_0;
    int sign_1;
    int zero_0;

    BIG_XXX x_0;
    BIG_XXX x_1;

    FP_YYY_redc(x_0, &(y.a));
    FP_YYY_redc(x_1, &(y.b));

    sign_0 = BIG_XXX_parity(x_0);
    sign_1 = BIG_XXX_parity(x_1);
    zero_0 = 0 - BIG_XXX_iszilch(x_0);

    return (sign_0 | (zero_0 & sign_1));
}

int ECP2_ZZZ_sswu(FP2_YYY *x, FP2_YYY *y, FP2_YYY u)
{
    if (x == NULL || y == NULL)
        return -1;

    FP2_YYY a;
    FP2_YYY b;
    FP2_YYY z;
    FP2_YYY gx;
    FP2_YYY tv1;
    FP2_YYY tmp;

    FP2_YYY_from_BIGs(&a, SSWU_A2re_ZZZ, SSWU_A2im_ZZZ);
    FP2_YYY_from_BIGs(&b, SSWU_B2re_ZZZ, SSWU_B2im_ZZZ);
    FP2_YYY_from_BIGs(&z, SSWU_Z2re_ZZZ, SSWU_Z2im_ZZZ);
    FP2_YYY_one(&gx);

    // tv1 = 1 / (Z^2 * u^4 + Z * u^2)
    FP2_YYY_sqr(&tmp, &u);
    FP2_YYY_mul(&tmp, &tmp, &z);
    FP2_YYY_sqr(&tv1, &tmp);
    FP2_YYY_add(&tv1, &tv1, &tmp);
    FP2_YYY_inv(&tv1, &tv1);

    // x = (-B / A) * (1 + tv1)
    FP2_YYY_add(x, &tv1, &gx);
    FP2_YYY_mul(x, x, &b);
    FP2_YYY_neg(x, x);
    FP2_YYY_inv(&gx, &a);
    FP2_YYY_mul(x, x, &gx);

    // if tv1 == 0, set x = B / (Z * A)
    if (FP2_YYY_iszilch(&tv1)) {
        FP2_YYY_mul(x, &b, &gx);
        FP2_YYY_inv(&gx, &z);
        FP2_YYY_mul(x, x, &gx);
    }

    // gx = x^3 + A * x + B
    FP2_YYY_sqr(&gx, x);
    FP2_YYY_add(&gx, &gx, &a);
    FP2_YYY_mul(&gx, &gx, x);
    FP2_YYY_add(&gx, &gx, &b);
    // y = sqrt(gx)
    FP2_YYY_sqrt(y, &gx);
    // tv1 = y^2
    FP2_YYY_sqr(&tv1, y);

    // If !(is_square(gx)), set x = Z * u^2 * x1 and y = sqrt(x2^3 + A * x2 + B)
    if (!FP2_YYY_equals(&gx, &tv1)) {
        FP2_YYY_mul(x, x, &tmp);
        FP2_YYY_sqr(&gx, x);
        FP2_YYY_add(&gx, &gx, &a);
        FP2_YYY_mul(&gx, &gx, x);
        FP2_YYY_add(&gx, &gx, &b);
        FP2_YYY_sqrt(y, &gx);
    }

    if (sgn0_fp2(*y) != sgn0_fp2(u))
        FP2_YYY_neg(y, y);

    return SUCCESS;
}

// Fast cofactor clearing as defined in https://www.ietf.org/archive/id/draft-irtf-cfrg-hash-to-curve-16.html#name-cofactor-clearing-for-bls12
int ECP2_ZZZ_clearcofactor(ECP2_ZZZ *Q)
{
    if (Q == NULL)
        return -1;

    ECP2_ZZZ xQ;
    ECP2_ZZZ x2Q;
    FP2_YYY X;
    FP2_YYY_from_BIGs(&X, Fra_BLS381, Frb_BLS381);

#if SEXTIC_TWIST_ZZZ==M_TYPE
    FP2_YYY_inv(&X,&X);
    FP2_YYY_norm(&X);
#endif

    ECP2_ZZZ_copy(&xQ, Q);
    ECP2_ZZZ_mul(&xQ, CURVE_Bnx_ZZZ);
    ECP2_ZZZ_copy(&x2Q, &xQ);
    ECP2_ZZZ_mul(&x2Q, CURVE_Bnx_ZZZ);

#if SIGN_OF_X_ZZZ == NEGATIVEX
    ECP2_ZZZ_neg(&xQ);
#endif

    ECP2_ZZZ_sub(&x2Q, &xQ);
    ECP2_ZZZ_sub(&x2Q, Q);
    ECP2_ZZZ_sub(&xQ, Q);
    ECP2_ZZZ_frob(&xQ, &X);
    ECP2_ZZZ_dbl(Q);
    ECP2_ZZZ_frob(Q, &X);
    ECP2_ZZZ_frob(Q, &X);
    ECP2_ZZZ_add(Q, &xQ);
    ECP2_ZZZ_add(Q, &x2Q);
    ECP2_ZZZ_affine(Q);

    return SUCCESS;
}

#endif