| /* |
| 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. |
| */ |
| |
| /* Elliptic Curve Point class */ |
| |
| public final class ECP { |
| private FP x; |
| private FP y; |
| private FP z; |
| private boolean INF; |
| |
| /* Constructor - set to O */ |
| public ECP() { |
| INF=true; |
| x=new FP(0); |
| y=new FP(1); |
| z=new FP(1); |
| } |
| /* test for O point-at-infinity */ |
| public boolean is_infinity() { |
| if (ROM.CURVETYPE==ROM.EDWARDS) |
| { |
| x.reduce(); y.reduce(); z.reduce(); |
| return (x.iszilch() && y.equals(z)); |
| } |
| else return INF; |
| } |
| /* Conditional swap of P and Q dependant on d */ |
| private void cswap(ECP Q,int d) |
| { |
| x.cswap(Q.x,d); |
| if (ROM.CURVETYPE!=ROM.MONTGOMERY) y.cswap(Q.y,d); |
| z.cswap(Q.z,d); |
| if (ROM.CURVETYPE!=ROM.EDWARDS) |
| { |
| boolean bd; |
| if (d==0) bd=false; |
| else bd=true; |
| bd=bd&(INF^Q.INF); |
| INF^=bd; |
| Q.INF^=bd; |
| } |
| } |
| |
| /* Conditional move of Q to P dependant on d */ |
| private void cmove(ECP Q,int d) |
| { |
| x.cmove(Q.x,d); |
| if (ROM.CURVETYPE!=ROM.MONTGOMERY) y.cmove(Q.y,d); |
| z.cmove(Q.z,d); |
| if (ROM.CURVETYPE!=ROM.EDWARDS) |
| { |
| boolean bd; |
| if (d==0) bd=false; |
| else bd=true; |
| INF^=(INF^Q.INF)&bd; |
| } |
| } |
| |
| /* return 1 if b==c, no branching */ |
| private static int teq(int b,int c) |
| { |
| int x=b^c; |
| x-=1; // if x=0, x now -1 |
| return ((x>>31)&1); |
| } |
| |
| /* Constant time select from pre-computed table */ |
| private void select(ECP W[],int b) |
| { |
| ECP MP=new ECP(); |
| int m=b>>31; |
| int babs=(b^m)-m; |
| |
| babs=(babs-1)/2; |
| |
| cmove(W[0],teq(babs,0)); // conditional move |
| cmove(W[1],teq(babs,1)); |
| cmove(W[2],teq(babs,2)); |
| cmove(W[3],teq(babs,3)); |
| cmove(W[4],teq(babs,4)); |
| cmove(W[5],teq(babs,5)); |
| cmove(W[6],teq(babs,6)); |
| cmove(W[7],teq(babs,7)); |
| |
| MP.copy(this); |
| MP.neg(); |
| cmove(MP,(int)(m&1)); |
| } |
| |
| /* Test P == Q */ |
| public boolean equals(ECP Q) { |
| if (is_infinity() && Q.is_infinity()) return true; |
| if (is_infinity() || Q.is_infinity()) return false; |
| if (ROM.CURVETYPE==ROM.WEIERSTRASS) |
| { |
| FP zs2=new FP(z); zs2.sqr(); |
| FP zo2=new FP(Q.z); zo2.sqr(); |
| FP zs3=new FP(zs2); zs3.mul(z); |
| FP zo3=new FP(zo2); zo3.mul(Q.z); |
| zs2.mul(Q.x); |
| zo2.mul(x); |
| if (!zs2.equals(zo2)) return false; |
| zs3.mul(Q.y); |
| zo3.mul(y); |
| if (!zs3.equals(zo3)) return false; |
| } |
| else |
| { |
| FP a=new FP(0); |
| FP b=new FP(0); |
| a.copy(x); a.mul(Q.z); a.reduce(); |
| b.copy(Q.x); b.mul(z); b.reduce(); |
| if (!a.equals(b)) return false; |
| if (ROM.CURVETYPE==ROM.EDWARDS) |
| { |
| a.copy(y); a.mul(Q.z); a.reduce(); |
| b.copy(Q.y); b.mul(z); b.reduce(); |
| if (!a.equals(b)) return false; |
| } |
| } |
| return true; |
| } |
| |
| /* this=P */ |
| public void copy(ECP P) |
| { |
| x.copy(P.x); |
| if (ROM.CURVETYPE!=ROM.MONTGOMERY) y.copy(P.y); |
| z.copy(P.z); |
| INF=P.INF; |
| } |
| /* this=-this */ |
| public void neg() { |
| if (is_infinity()) return; |
| if (ROM.CURVETYPE==ROM.WEIERSTRASS) |
| { |
| y.neg(); y.norm(); |
| } |
| if (ROM.CURVETYPE==ROM.EDWARDS) |
| { |
| x.neg(); x.norm(); |
| } |
| return; |
| } |
| /* set this=O */ |
| public void inf() { |
| INF=true; |
| x.zero(); |
| y.one(); |
| z.one(); |
| // y=new FP(1); |
| // z=new FP(1); |
| } |
| |
| /* Calculate RHS of curve equation */ |
| public static FP RHS(FP x) { |
| x.norm(); |
| FP r=new FP(x); |
| r.sqr(); |
| |
| if (ROM.CURVETYPE==ROM.WEIERSTRASS) |
| { // x^3+Ax+B |
| FP b=new FP(new BIG(ROM.CURVE_B)); |
| r.mul(x); |
| if (ROM.CURVE_A==-3) |
| { |
| FP cx=new FP(x); |
| cx.imul(3); |
| cx.neg(); cx.norm(); |
| r.add(cx); |
| } |
| r.add(b); |
| } |
| if (ROM.CURVETYPE==ROM.EDWARDS) |
| { // (Ax^2-1)/(Bx^2-1) |
| FP b=new FP(new BIG(ROM.CURVE_B)); |
| |
| FP one=new FP(1); |
| b.mul(r); |
| b.sub(one); |
| if (ROM.CURVE_A==-1) r.neg(); |
| r.sub(one); |
| |
| b.inverse(); |
| |
| r.mul(b); |
| } |
| if (ROM.CURVETYPE==ROM.MONTGOMERY) |
| { // x^3+Ax^2+x |
| FP x3=new FP(0); |
| x3.copy(r); |
| x3.mul(x); |
| r.imul(ROM.CURVE_A); |
| r.add(x3); |
| r.add(x); |
| } |
| r.reduce(); |
| return r; |
| } |
| |
| /* set (x,y) from two BIGs */ |
| public ECP(BIG ix,BIG iy) { |
| x=new FP(ix); |
| y=new FP(iy); |
| z=new FP(1); |
| FP rhs=RHS(x); |
| |
| if (ROM.CURVETYPE==ROM.MONTGOMERY) |
| { |
| if (rhs.jacobi()==1) INF=false; |
| else inf(); |
| } |
| else |
| { |
| FP y2=new FP(y); |
| y2.sqr(); |
| if (y2.equals(rhs)) INF=false; |
| else inf(); |
| } |
| } |
| /* set (x,y) from BIG and a bit */ |
| public ECP(BIG ix,int s) { |
| x=new FP(ix); |
| FP rhs=RHS(x); |
| y=new FP(0); |
| z=new FP(1); |
| if (rhs.jacobi()==1) |
| { |
| FP ny=rhs.sqrt(); |
| if (ny.redc().parity()!=s) ny.neg(); |
| y.copy(ny); |
| INF=false; |
| } |
| else inf(); |
| } |
| |
| /* set from x - calculate y from curve equation */ |
| public ECP(BIG ix) { |
| x=new FP(ix); |
| FP rhs=RHS(x); |
| y=new FP(0); |
| z=new FP(1); |
| if (rhs.jacobi()==1) |
| { |
| if (ROM.CURVETYPE!=ROM.MONTGOMERY) y.copy(rhs.sqrt()); |
| INF=false; |
| } |
| else INF=true; |
| } |
| |
| /* set to affine - from (x,y,z) to (x,y) */ |
| public void affine() { |
| if (is_infinity()) return; |
| FP one=new FP(1); |
| if (z.equals(one)) return; |
| z.inverse(); |
| if (ROM.CURVETYPE==ROM.WEIERSTRASS) |
| { |
| FP z2=new FP(z); |
| z2.sqr(); |
| x.mul(z2); x.reduce(); |
| y.mul(z2); |
| y.mul(z); y.reduce(); |
| } |
| if (ROM.CURVETYPE==ROM.EDWARDS) |
| { |
| x.mul(z); x.reduce(); |
| y.mul(z); y.reduce(); |
| } |
| if (ROM.CURVETYPE==ROM.MONTGOMERY) |
| { |
| x.mul(z); x.reduce(); |
| } |
| z.copy(one); |
| } |
| /* extract x as a BIG */ |
| public BIG getX() |
| { |
| affine(); |
| return x.redc(); |
| } |
| /* extract y as a BIG */ |
| public BIG getY() |
| { |
| affine(); |
| return y.redc(); |
| } |
| |
| /* get sign of Y */ |
| public int getS() |
| { |
| affine(); |
| BIG y=getY(); |
| return y.parity(); |
| } |
| /* extract x as an FP */ |
| public FP getx() |
| { |
| return x; |
| } |
| /* extract y as an FP */ |
| public FP gety() |
| { |
| return y; |
| } |
| /* extract z as an FP */ |
| public FP getz() |
| { |
| return z; |
| } |
| /* convert to byte array */ |
| public void toBytes(byte[] b) |
| { |
| byte[] t=new byte[ROM.MODBYTES]; |
| if (ROM.CURVETYPE!=ROM.MONTGOMERY) b[0]=0x04; |
| else b[0]=0x02; |
| |
| affine(); |
| x.redc().toBytes(t); |
| for (int i=0;i<ROM.MODBYTES;i++) b[i+1]=t[i]; |
| if (ROM.CURVETYPE!=ROM.MONTGOMERY) |
| { |
| y.redc().toBytes(t); |
| for (int i=0;i<ROM.MODBYTES;i++) b[i+ROM.MODBYTES+1]=t[i]; |
| } |
| } |
| /* convert from byte array to point */ |
| public static ECP fromBytes(byte[] b) |
| { |
| byte[] t=new byte[ROM.MODBYTES]; |
| BIG p=new BIG(ROM.Modulus); |
| |
| for (int i=0;i<ROM.MODBYTES;i++) t[i]=b[i+1]; |
| BIG px=BIG.fromBytes(t); |
| if (BIG.comp(px,p)>=0) return new ECP(); |
| |
| if (b[0]==0x04) |
| { |
| for (int i=0;i<ROM.MODBYTES;i++) t[i]=b[i+ROM.MODBYTES+1]; |
| BIG py=BIG.fromBytes(t); |
| if (BIG.comp(py,p)>=0) return new ECP(); |
| return new ECP(px,py); |
| } |
| else return new ECP(px); |
| } |
| /* convert to hex string */ |
| public String toString() { |
| if (is_infinity()) return "infinity"; |
| affine(); |
| if (ROM.CURVETYPE==ROM.MONTGOMERY) return "("+x.redc().toString()+")"; |
| else return "("+x.redc().toString()+","+y.redc().toString()+")"; |
| } |
| /* this*=2 */ |
| public void dbl() { |
| if (ROM.CURVETYPE==ROM.WEIERSTRASS) |
| { |
| if (INF) return; |
| if (y.iszilch()) |
| { |
| inf(); |
| return; |
| } |
| |
| FP w1=new FP(x); |
| FP w6=new FP(z); |
| FP w2=new FP(0); |
| FP w3=new FP(x); |
| FP w8=new FP(x); |
| |
| if (ROM.CURVE_A==-3) |
| { |
| w6.sqr(); |
| w1.copy(w6); |
| w1.neg(); |
| w3.add(w1); |
| w8.add(w6); |
| w3.mul(w8); |
| w8.copy(w3); |
| w8.imul(3); |
| } |
| else |
| { |
| 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); |
| y.sub(w2); |
| y.norm(); |
| z.norm(); |
| } |
| if (ROM.CURVETYPE==ROM.EDWARDS) |
| { |
| FP C=new FP(x); |
| FP D=new FP(y); |
| FP H=new FP(z); |
| FP J=new FP(0); |
| |
| x.mul(y); x.add(x); |
| C.sqr(); |
| D.sqr(); |
| if (ROM.CURVE_A==-1) C.neg(); |
| y.copy(C); y.add(D); |
| y.norm(); |
| H.sqr(); H.add(H); |
| z.copy(y); |
| J.copy(y); J.sub(H); |
| x.mul(J); |
| C.sub(D); |
| y.mul(C); |
| z.mul(J); |
| |
| x.norm(); |
| y.norm(); |
| z.norm(); |
| } |
| if (ROM.CURVETYPE==ROM.MONTGOMERY) |
| { |
| FP A=new FP(x); |
| FP B=new FP(x); |
| FP AA=new FP(0); |
| FP BB=new FP(0); |
| FP C=new FP(0); |
| |
| if (INF) return; |
| |
| A.add(z); |
| AA.copy(A); AA.sqr(); |
| B.sub(z); |
| BB.copy(B); BB.sqr(); |
| C.copy(AA); C.sub(BB); |
| |
| x.copy(AA); x.mul(BB); |
| |
| A.copy(C); A.imul((ROM.CURVE_A+2)/4); |
| |
| BB.add(A); |
| z.copy(BB); z.mul(C); |
| x.norm(); |
| z.norm(); |
| } |
| return; |
| } |
| |
| /* this+=Q */ |
| public void add(ECP Q) { |
| if (ROM.CURVETYPE==ROM.WEIERSTRASS) |
| { |
| if (INF) |
| { |
| copy(Q); |
| return; |
| } |
| if (Q.INF) return; |
| |
| boolean aff=false; |
| |
| FP one=new FP(1); |
| if (Q.z.equals(one)) aff=true; |
| |
| FP A,C; |
| FP B=new FP(z); |
| FP D=new FP(z); |
| if (!aff) |
| { |
| A=new FP(Q.z); |
| C=new FP(Q.z); |
| |
| A.sqr(); B.sqr(); |
| C.mul(A); D.mul(B); |
| |
| A.mul(x); |
| C.mul(y); |
| } |
| else |
| { |
| A=new FP(x); |
| C=new FP(y); |
| |
| B.sqr(); |
| D.mul(B); |
| } |
| |
| B.mul(Q.x); B.sub(A); |
| D.mul(Q.y); D.sub(C); |
| |
| if (B.iszilch()) |
| { |
| if (D.iszilch()) |
| { |
| dbl(); |
| return; |
| } |
| else |
| { |
| INF=true; |
| return; |
| } |
| } |
| |
| if (!aff) z.mul(Q.z); |
| z.mul(B); |
| |
| FP e=new FP(B); e.sqr(); |
| B.mul(e); |
| A.mul(e); |
| |
| e.copy(A); |
| e.add(A); e.add(B); |
| x.copy(D); x.sqr(); x.sub(e); |
| |
| A.sub(x); |
| y.copy(A); y.mul(D); |
| C.mul(B); y.sub(C); |
| |
| x.norm(); |
| y.norm(); |
| z.norm(); |
| } |
| if (ROM.CURVETYPE==ROM.EDWARDS) |
| { |
| FP b=new FP(new BIG(ROM.CURVE_B)); |
| FP A=new FP(z); |
| FP B=new FP(0); |
| FP C=new FP(x); |
| FP D=new FP(y); |
| FP E=new FP(0); |
| FP F=new FP(0); |
| FP G=new FP(0); |
| // FP H=new FP(0); |
| // FP I=new FP(0); |
| |
| A.mul(Q.z); |
| B.copy(A); B.sqr(); |
| C.mul(Q.x); |
| D.mul(Q.y); |
| |
| E.copy(C); E.mul(D); E.mul(b); |
| F.copy(B); F.sub(E); |
| G.copy(B); G.add(E); |
| |
| if (ROM.CURVE_A==1) |
| { |
| E.copy(D); E.sub(C); |
| } |
| C.add(D); |
| |
| B.copy(x); B.add(y); |
| D.copy(Q.x); D.add(Q.y); |
| B.mul(D); |
| B.sub(C); |
| B.mul(F); |
| x.copy(A); x.mul(B); |
| |
| if (ROM.CURVE_A==1) |
| { |
| C.copy(E); C.mul(G); |
| } |
| if (ROM.CURVE_A==-1) |
| { |
| C.mul(G); |
| } |
| y.copy(A); y.mul(C); |
| z.copy(F); z.mul(G); |
| x.norm(); y.norm(); z.norm(); |
| } |
| return; |
| } |
| |
| /* Differential Add for Montgomery curves. this+=Q where W is this-Q and is affine. */ |
| public void dadd(ECP Q,ECP W) { |
| FP A=new FP(x); |
| FP B=new FP(x); |
| FP C=new FP(Q.x); |
| FP D=new FP(Q.x); |
| FP DA=new FP(0); |
| FP CB=new FP(0); |
| |
| A.add(z); |
| B.sub(z); |
| |
| C.add(Q.z); |
| D.sub(Q.z); |
| |
| DA.copy(D); DA.mul(A); |
| CB.copy(C); CB.mul(B); |
| |
| A.copy(DA); A.add(CB); A.sqr(); |
| B.copy(DA); B.sub(CB); B.sqr(); |
| |
| x.copy(A); |
| z.copy(W.x); z.mul(B); |
| |
| if (z.iszilch()) inf(); |
| else INF=false; |
| |
| x.norm(); |
| } |
| /* this-=Q */ |
| public void sub(ECP Q) { |
| Q.neg(); |
| add(Q); |
| Q.neg(); |
| } |
| |
| public static void multiaffine(int m,ECP[] P) |
| { |
| int i; |
| FP t1=new FP(0); |
| FP t2=new FP(0); |
| |
| FP[] work=new FP[m]; |
| |
| for (i=0;i<m;i++) |
| work[i]=new FP(0); |
| |
| work[0].one(); |
| work[1].copy(P[0].z); |
| |
| for (i=2;i<m;i++) |
| { |
| work[i].copy(work[i-1]); |
| work[i].mul(P[i-1].z); |
| } |
| |
| t1.copy(work[m-1]); |
| t1.mul(P[m-1].z); |
| t1.inverse(); |
| t2.copy(P[m-1].z); |
| work[m-1].mul(t1); |
| |
| for (i=m-2;;i--) |
| { |
| if (i==0) |
| { |
| work[0].copy(t1); |
| work[0].mul(t2); |
| break; |
| } |
| work[i].mul(t2); |
| work[i].mul(t1); |
| t2.mul(P[i].z); |
| } |
| /* now work[] contains inverses of all Z coordinates */ |
| |
| for (i=0;i<m;i++) |
| { |
| P[i].z.one(); |
| t1.copy(work[i]); |
| t1.sqr(); |
| P[i].x.mul(t1); |
| t1.mul(work[i]); |
| P[i].y.mul(t1); |
| } |
| } |
| |
| /* constant time multiply by small integer of length bts - use ladder */ |
| public ECP pinmul(int e,int bts) { |
| if (ROM.CURVETYPE==ROM.MONTGOMERY) |
| return this.mul(new BIG(e)); |
| else |
| { |
| int nb,i,b; |
| ECP P=new ECP(); |
| ECP R0=new ECP(); |
| ECP R1=new ECP(); R1.copy(this); |
| |
| for (i=bts-1;i>=0;i--) |
| { |
| b=(e>>i)&1; |
| P.copy(R1); |
| P.add(R0); |
| R0.cswap(R1,b); |
| R1.copy(P); |
| R0.dbl(); |
| R0.cswap(R1,b); |
| } |
| P.copy(R0); |
| P.affine(); |
| return P; |
| } |
| } |
| |
| /* return e.this */ |
| |
| public ECP mul(BIG e) { |
| if (e.iszilch() || is_infinity()) return new ECP(); |
| ECP P=new ECP(); |
| if (ROM.CURVETYPE==ROM.MONTGOMERY) |
| { |
| /* use Ladder */ |
| int nb,i,b; |
| ECP D=new ECP(); |
| ECP R0=new ECP(); R0.copy(this); |
| ECP R1=new ECP(); R1.copy(this); |
| R1.dbl(); |
| D.copy(this); D.affine(); |
| nb=e.nbits(); |
| for (i=nb-2;i>=0;i--) |
| { |
| b=e.bit(i); |
| P.copy(R1); |
| P.dadd(R0,D); |
| R0.cswap(R1,b); |
| R1.copy(P); |
| R0.dbl(); |
| R0.cswap(R1,b); |
| } |
| P.copy(R0); |
| } |
| else |
| { |
| // fixed size windows |
| int i,b,nb,m,s,ns; |
| BIG mt=new BIG(); |
| BIG t=new BIG(); |
| ECP Q=new ECP(); |
| ECP C=new ECP(); |
| ECP[] W=new ECP[8]; |
| byte[] w=new byte[1+(ROM.NLEN*ROM.BASEBITS+3)/4]; |
| |
| affine(); |
| |
| // precompute table |
| Q.copy(this); |
| Q.dbl(); |
| W[0]=new ECP(); |
| W[0].copy(this); |
| |
| for (i=1;i<8;i++) |
| { |
| W[i]=new ECP(); |
| W[i].copy(W[i-1]); |
| W[i].add(Q); |
| } |
| |
| // convert the table to affine |
| if (ROM.CURVETYPE==ROM.WEIERSTRASS) |
| multiaffine(8,W); |
| |
| // make exponent odd - add 2P if even, P if odd |
| t.copy(e); |
| s=t.parity(); |
| t.inc(1); t.norm(); ns=t.parity(); mt.copy(t); mt.inc(1); mt.norm(); |
| t.cmove(mt,s); |
| Q.cmove(this,ns); |
| C.copy(Q); |
| |
| nb=1+(t.nbits()+3)/4; |
| |
| // convert exponent to signed 4-bit window |
| for (i=0;i<nb;i++) |
| { |
| w[i]=(byte)(t.lastbits(5)-16); |
| t.dec(w[i]); t.norm(); |
| t.fshr(4); |
| } |
| w[nb]=(byte)t.lastbits(5); |
| |
| P.copy(W[(w[nb]-1)/2]); |
| for (i=nb-1;i>=0;i--) |
| { |
| Q.select(W,w[i]); |
| P.dbl(); |
| P.dbl(); |
| P.dbl(); |
| P.dbl(); |
| P.add(Q); |
| } |
| P.sub(C); /* apply correction */ |
| } |
| P.affine(); |
| return P; |
| } |
| |
| /* Return e.this+f.Q */ |
| |
| public ECP mul2(BIG e,ECP Q,BIG f) { |
| BIG te=new BIG(); |
| BIG tf=new BIG(); |
| BIG mt=new BIG(); |
| ECP S=new ECP(); |
| ECP T=new ECP(); |
| ECP C=new ECP(); |
| ECP[] W=new ECP[8]; |
| byte[] w=new byte[1+(ROM.NLEN*ROM.BASEBITS+1)/2]; |
| int i,s,ns,nb; |
| byte a,b; |
| |
| affine(); |
| Q.affine(); |
| |
| te.copy(e); |
| tf.copy(f); |
| |
| // precompute table |
| W[1]=new ECP(); W[1].copy(this); W[1].sub(Q); |
| W[2]=new ECP(); W[2].copy(this); W[2].add(Q); |
| S.copy(Q); S.dbl(); |
| W[0]=new ECP(); W[0].copy(W[1]); W[0].sub(S); |
| W[3]=new ECP(); W[3].copy(W[2]); W[3].add(S); |
| T.copy(this); T.dbl(); |
| W[5]=new ECP(); W[5].copy(W[1]); W[5].add(T); |
| W[6]=new ECP(); W[6].copy(W[2]); W[6].add(T); |
| W[4]=new ECP(); W[4].copy(W[5]); W[4].sub(S); |
| W[7]=new ECP(); W[7].copy(W[6]); W[7].add(S); |
| |
| // convert the table to affine |
| if (ROM.CURVETYPE==ROM.WEIERSTRASS) |
| multiaffine(8,W); |
| |
| // if multiplier is odd, add 2, else add 1 to multiplier, and add 2P or P to correction |
| |
| s=te.parity(); |
| te.inc(1); te.norm(); ns=te.parity(); mt.copy(te); mt.inc(1); mt.norm(); |
| te.cmove(mt,s); |
| T.cmove(this,ns); |
| C.copy(T); |
| |
| s=tf.parity(); |
| tf.inc(1); tf.norm(); ns=tf.parity(); mt.copy(tf); mt.inc(1); mt.norm(); |
| tf.cmove(mt,s); |
| S.cmove(Q,ns); |
| C.add(S); |
| |
| mt.copy(te); mt.add(tf); mt.norm(); |
| nb=1+(mt.nbits()+1)/2; |
| |
| // convert exponent to signed 2-bit window |
| for (i=0;i<nb;i++) |
| { |
| a=(byte)(te.lastbits(3)-4); |
| te.dec(a); te.norm(); |
| te.fshr(2); |
| b=(byte)(tf.lastbits(3)-4); |
| tf.dec(b); tf.norm(); |
| tf.fshr(2); |
| w[i]=(byte)(4*a+b); |
| } |
| w[nb]=(byte)(4*te.lastbits(3)+tf.lastbits(3)); |
| S.copy(W[(w[nb]-1)/2]); |
| |
| for (i=nb-1;i>=0;i--) |
| { |
| T.select(W,w[i]); |
| S.dbl(); |
| S.dbl(); |
| S.add(T); |
| } |
| S.sub(C); /* apply correction */ |
| S.affine(); |
| return S; |
| } |
| |
| /* |
| public static void main(String[] args) { |
| |
| BIG Gx=new BIG(ROM.CURVE_Gx); |
| BIG Gy; |
| ECP P; |
| if (ROM.CURVETYPE!=ROM.MONTGOMERY) Gy=new BIG(ROM.CURVE_Gy); |
| BIG r=new BIG(ROM.CURVE_Order); |
| |
| //r.dec(7); |
| |
| System.out.println("Gx= "+Gx.toString()); |
| if (ROM.CURVETYPE!=ROM.MONTGOMERY) System.out.println("Gy= "+Gy.toString()); |
| |
| if (ROM.CURVETYPE!=ROM.MONTGOMERY) P=new ECP(Gx,Gy); |
| else P=new ECP(Gx); |
| |
| System.out.println("P= "+P.toString()); |
| |
| ECP R=P.mul(r); |
| //for (int i=0;i<10000;i++) |
| // R=P.mul(r); |
| |
| System.out.println("R= "+R.toString()); |
| } */ |
| } |
| |