/* this+=this */ public int dbl() { if (INF) { return(-1); } if (y.iszilch()) { inf(); return(-1); } FP2 w1 = new FP2(x); FP2 w2 = new FP2(0); FP2 w3 = new FP2(x); FP2 w8 = new FP2(x); w1.sqr(); w8.copy(w1); w8.imul(3); w2.copy(y); w2.sqr(); w3.copy(x); w3.mul(w2); w3.imul(4); w1.copy(w3); w1.neg(); // w1.norm(); x.copy(w8); x.sqr(); x.add(w1); x.add(w1); x.norm(); z.mul(y); z.add(z); w2.add(w2); w2.sqr(); w2.add(w2); w3.sub(x); y.copy(w8); y.mul(w3); // w2.norm(); y.sub(w2); y.norm(); z.norm(); return(1); }
/* this*=c where c is int */ public void imul(int c) { a.imul(c); b.imul(c); }
/* Line function */ public static FP12 line(ECP2 A, ECP2 B, FP Qx, FP Qy) { ECP2 P = new ECP2(); FP4 a, b, c; P.copy(A); FP2 ZZ = new FP2(P.getz()); ZZ.sqr(); int D; if (A == B) { D = A.dbl(); // Check this return value in amcl_ec2.c } else { D = A.add(B); } if (D < 0) { return(new FP12(1)); } FP2 Z3 = new FP2(A.getz()); c = new FP4(0); if (D == 0) { // Addition FP2 X = new FP2(B.getx()); FP2 Y = new FP2(B.gety()); FP2 T = new FP2(P.getz()); T.mul(Y); ZZ.mul(T); FP2 NY = new FP2(P.gety()); NY.neg(); ZZ.add(NY); Z3.pmul(Qy); T.mul(P.getx()); X.mul(NY); T.add(X); a = new FP4(Z3, T); ZZ.neg(); ZZ.pmul(Qx); b = new FP4(ZZ); } else { // Doubling FP2 X = new FP2(P.getx()); FP2 Y = new FP2(P.gety()); FP2 T = new FP2(P.getx()); T.sqr(); T.imul(3); Y.sqr(); Y.add(Y); Z3.mul(ZZ); Z3.pmul(Qy); X.mul(T); X.sub(Y); a = new FP4(Z3, X); T.neg(); ZZ.mul(T); ZZ.pmul(Qx); b = new FP4(ZZ); } return(new FP12(a, b, c)); }