| /* |
| 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. |
| */ |
| |
| /* Finite Field arithmetic Fp^16 functions */ |
| |
| /* FP16 elements are of the form a+ib, where i is sqrt(sqrt(sqrt(-1+sqrt(-1)))) */ |
| |
| package org.apache.milagro.amcl.XXX; |
| |
| public final class FP16 { |
| private final FP8 a; |
| private final FP8 b; |
| /* reduce all components of this mod Modulus */ |
| public void reduce() |
| { |
| a.reduce(); |
| b.reduce(); |
| } |
| /* normalise all components of this mod Modulus */ |
| public void norm() |
| { |
| a.norm(); |
| b.norm(); |
| } |
| /* test this==0 ? */ |
| public boolean iszilch() { |
| return (a.iszilch() && b.iszilch()); |
| } |
| |
| public void cmove(FP16 g,int d) |
| { |
| a.cmove(g.a,d); |
| b.cmove(g.b,d); |
| } |
| |
| /* test this==1 ? */ |
| public boolean isunity() { |
| FP8 one=new FP8(1); |
| return (a.equals(one) && b.iszilch()); |
| } |
| |
| /* test is w real? That is in a+ib test b is zero */ |
| public boolean isreal() |
| { |
| return b.iszilch(); |
| } |
| /* extract real part a */ |
| public FP8 real() |
| { |
| return a; |
| } |
| |
| public FP8 geta() |
| { |
| return a; |
| } |
| /* extract imaginary part b */ |
| public FP8 getb() |
| { |
| return b; |
| } |
| /* test this=x? */ |
| public boolean equals(FP16 x) |
| { |
| return (a.equals(x.a) && b.equals(x.b)); |
| } |
| /* constructors */ |
| public FP16(int c) |
| { |
| a=new FP8(c); |
| b=new FP8(0); |
| } |
| |
| public FP16(FP16 x) |
| { |
| a=new FP8(x.a); |
| b=new FP8(x.b); |
| } |
| |
| public FP16(FP8 c,FP8 d) |
| { |
| a=new FP8(c); |
| b=new FP8(d); |
| } |
| |
| public FP16(FP8 c) |
| { |
| a=new FP8(c); |
| b=new FP8(0); |
| } |
| /* copy this=x */ |
| public void copy(FP16 x) |
| { |
| a.copy(x.a); |
| b.copy(x.b); |
| } |
| /* set this=0 */ |
| public void zero() |
| { |
| a.zero(); |
| b.zero(); |
| } |
| |
| /* set this=1 */ |
| public void one() |
| { |
| a.one(); |
| b.zero(); |
| } |
| /* set this=-this */ |
| public void neg() |
| { |
| norm(); |
| FP8 m=new FP8(a); |
| FP8 t=new FP8(0); |
| m.add(b); |
| m.neg(); |
| t.copy(m); t.add(b); |
| b.copy(m); |
| b.add(a); |
| a.copy(t); |
| norm(); |
| } |
| |
| /* this=conjugate(this) */ |
| public void conj() |
| { |
| b.neg(); norm(); |
| } |
| /* this=-conjugate(this) */ |
| public void nconj() |
| { |
| a.neg(); norm(); |
| } |
| /* this+=x */ |
| public void add(FP16 x) |
| { |
| a.add(x.a); |
| b.add(x.b); |
| } |
| /* this-=x */ |
| public void sub(FP16 x) |
| { |
| FP16 m=new FP16(x); |
| m.neg(); |
| add(m); |
| } |
| |
| /* this=x-this */ |
| public void rsub(FP16 x) |
| { |
| neg(); |
| add(x); |
| } |
| |
| /* this*=s where s is FP8 */ |
| public void pmul(FP8 s) |
| { |
| a.mul(s); |
| b.mul(s); |
| } |
| /* this*=s where s is FP2 */ |
| public void qmul(FP2 s) |
| { |
| a.qmul(s); |
| b.qmul(s); |
| } |
| |
| /* this*=c where c is int */ |
| public void imul(int c) |
| { |
| a.imul(c); |
| b.imul(c); |
| } |
| |
| /* this*=this */ |
| public void sqr() |
| { |
| FP8 t1=new FP8(a); |
| FP8 t2=new FP8(b); |
| FP8 t3=new FP8(a); |
| |
| t3.mul(b); |
| t1.add(b); |
| t2.times_i(); |
| |
| t2.add(a); |
| |
| t1.norm(); |
| t2.norm(); |
| |
| a.copy(t1); |
| |
| a.mul(t2); |
| |
| t2.copy(t3); |
| t2.times_i(); |
| t2.add(t3); |
| t2.norm(); |
| t2.neg(); |
| a.add(t2); |
| |
| b.copy(t3); |
| b.add(t3); |
| |
| norm(); |
| } |
| |
| /* this*=y */ |
| public void mul(FP16 y) |
| { |
| FP8 t1=new FP8(a); |
| FP8 t2=new FP8(b); |
| FP8 t3=new FP8(0); |
| FP8 t4=new FP8(b); |
| |
| t1.mul(y.a); |
| t2.mul(y.b); |
| t3.copy(y.b); |
| t3.add(y.a); |
| t4.add(a); |
| |
| t3.norm(); |
| t4.norm(); |
| |
| t4.mul(t3); |
| |
| t3.copy(t1); |
| t3.neg(); |
| t4.add(t3); |
| t4.norm(); |
| |
| t3.copy(t2); |
| t3.neg(); |
| b.copy(t4); |
| b.add(t3); |
| |
| t2.times_i(); |
| a.copy(t2); |
| a.add(t1); |
| |
| norm(); |
| } |
| |
| /* convert this to hex string */ |
| public String toString() |
| { |
| return ("["+a.toString()+","+b.toString()+"]"); |
| } |
| |
| /* this=1/this */ |
| public void inverse() |
| { |
| FP8 t1=new FP8(a); |
| FP8 t2=new FP8(b); |
| |
| t1.sqr(); |
| t2.sqr(); |
| t2.times_i(); |
| t2.norm(); |
| t1.sub(t2); t1.norm(); |
| t1.inverse(); |
| a.mul(t1); |
| t1.neg(); |
| t1.norm(); |
| b.mul(t1); |
| } |
| |
| /* this*=i where i = sqrt(-1+sqrt(-1)) */ |
| public void times_i() |
| { |
| FP8 s=new FP8(b); |
| FP8 t=new FP8(a); |
| s.times_i(); |
| b.copy(t); |
| a.copy(s); |
| norm(); |
| } |
| |
| public void times_i2() |
| { |
| a.times_i(); |
| b.times_i(); |
| } |
| |
| public void times_i4() |
| { |
| a.times_i2(); |
| b.times_i2(); |
| } |
| |
| /* this=this^p using Frobenius */ |
| public void frob(FP2 f) |
| { |
| FP2 ff=new FP2(f); ff.sqr(); ff.norm(); |
| |
| a.frob(ff); |
| b.frob(ff); |
| b.qmul(f); |
| b.times_i(); |
| } |
| |
| /* this=this^e */ |
| public FP16 pow(BIG e) |
| { |
| FP16 w=new FP16(this); |
| w.norm(); |
| BIG z=new BIG(e); |
| FP16 r=new FP16(1); |
| z.norm(); |
| while (true) |
| { |
| int bt=z.parity(); |
| z.fshr(1); |
| if (bt==1) r.mul(w); |
| if (z.iszilch()) break; |
| w.sqr(); |
| } |
| r.reduce(); |
| return r; |
| } |
| |
| /* XTR xtr_a function */ |
| public void xtr_A(FP16 w,FP16 y,FP16 z) |
| { |
| FP16 r=new FP16(w); |
| FP16 t=new FP16(w); |
| |
| r.sub(y); |
| r.norm(); |
| r.pmul(a); |
| t.add(y); |
| t.norm(); |
| t.pmul(b); |
| t.times_i(); |
| |
| copy(r); |
| add(t); |
| add(z); |
| |
| norm(); |
| } |
| |
| /* XTR xtr_d function */ |
| public void xtr_D() { |
| FP16 w=new FP16(this); |
| sqr(); w.conj(); |
| w.add(w); |
| w.norm(); |
| sub(w); |
| reduce(); |
| } |
| |
| /* r=x^n using XTR method on traces of FP12s */ |
| public FP16 xtr_pow(BIG n) { |
| FP16 sf=new FP16(this); |
| sf.norm(); |
| FP16 a=new FP16(3); |
| FP16 b=new FP16(sf); |
| FP16 c=new FP16(b); |
| c.xtr_D(); |
| FP16 t=new FP16(0); |
| FP16 r=new FP16(0); |
| |
| |
| int par=n.parity(); |
| BIG v=new BIG(n); v.norm(); v.fshr(1); |
| if (par==0) {v.dec(1); v.norm();} |
| |
| int nb=v.nbits(); |
| for (int i=nb-1;i>=0;i--) |
| { |
| if (v.bit(i)!=1) |
| { |
| t.copy(b); |
| sf.conj(); |
| c.conj(); |
| b.xtr_A(a,sf,c); |
| sf.conj(); |
| c.copy(t); |
| c.xtr_D(); |
| a.xtr_D(); |
| } |
| else |
| { |
| t.copy(a); t.conj(); |
| a.copy(b); |
| a.xtr_D(); |
| b.xtr_A(c,sf,t); |
| c.xtr_D(); |
| } |
| } |
| if (par==0) r.copy(c); |
| else r.copy(b); |
| r.reduce(); |
| return r; |
| } |
| |
| /* r=ck^a.cl^n using XTR double exponentiation method on traces of FP12s. See Stam thesis. */ |
| public FP16 xtr_pow2(FP16 ck,FP16 ckml,FP16 ckm2l,BIG a,BIG b) |
| { |
| BIG e=new BIG(a); |
| BIG d=new BIG(b); |
| BIG w=new BIG(0); |
| d.norm(); d.norm(); |
| FP16 cu=new FP16(ck); // can probably be passed in w/o copying |
| FP16 cv=new FP16(this); |
| FP16 cumv=new FP16(ckml); |
| FP16 cum2v=new FP16(ckm2l); |
| FP16 r=new FP16(0); |
| FP16 t=new FP16(0); |
| |
| int f2=0; |
| while (d.parity()==0 && e.parity()==0) |
| { |
| d.fshr(1); |
| e.fshr(1); |
| f2++; |
| } |
| |
| while (BIG.comp(d,e)!=0) |
| { |
| if (BIG.comp(d,e)>0) |
| { |
| w.copy(e); w.imul(4); w.norm(); |
| if (BIG.comp(d,w)<=0) |
| { |
| w.copy(d); d.copy(e); |
| e.rsub(w); e.norm(); |
| |
| t.copy(cv); |
| t.xtr_A(cu,cumv,cum2v); |
| cum2v.copy(cumv); |
| cum2v.conj(); |
| cumv.copy(cv); |
| cv.copy(cu); |
| cu.copy(t); |
| |
| } |
| else if (d.parity()==0) |
| { |
| d.fshr(1); |
| r.copy(cum2v); r.conj(); |
| t.copy(cumv); |
| t.xtr_A(cu,cv,r); |
| cum2v.copy(cumv); |
| cum2v.xtr_D(); |
| cumv.copy(t); |
| cu.xtr_D(); |
| } |
| else if (e.parity()==1) |
| { |
| d.sub(e); d.norm(); |
| d.fshr(1); |
| t.copy(cv); |
| t.xtr_A(cu,cumv,cum2v); |
| cu.xtr_D(); |
| cum2v.copy(cv); |
| cum2v.xtr_D(); |
| cum2v.conj(); |
| cv.copy(t); |
| } |
| else |
| { |
| w.copy(d); |
| d.copy(e); d.fshr(1); |
| e.copy(w); |
| t.copy(cumv); |
| t.xtr_D(); |
| cumv.copy(cum2v); cumv.conj(); |
| cum2v.copy(t); cum2v.conj(); |
| t.copy(cv); |
| t.xtr_D(); |
| cv.copy(cu); |
| cu.copy(t); |
| } |
| } |
| if (BIG.comp(d,e)<0) |
| { |
| w.copy(d); w.imul(4); w.norm(); |
| if (BIG.comp(e,w)<=0) |
| { |
| e.sub(d); e.norm(); |
| t.copy(cv); |
| t.xtr_A(cu,cumv,cum2v); |
| cum2v.copy(cumv); |
| cumv.copy(cu); |
| cu.copy(t); |
| } |
| else if (e.parity()==0) |
| { |
| w.copy(d); |
| d.copy(e); d.fshr(1); |
| e.copy(w); |
| t.copy(cumv); |
| t.xtr_D(); |
| cumv.copy(cum2v); cumv.conj(); |
| cum2v.copy(t); cum2v.conj(); |
| t.copy(cv); |
| t.xtr_D(); |
| cv.copy(cu); |
| cu.copy(t); |
| } |
| else if (d.parity()==1) |
| { |
| w.copy(e); |
| e.copy(d); |
| w.sub(d); w.norm(); |
| d.copy(w); d.fshr(1); |
| t.copy(cv); |
| t.xtr_A(cu,cumv,cum2v); |
| cumv.conj(); |
| cum2v.copy(cu); |
| cum2v.xtr_D(); |
| cum2v.conj(); |
| cu.copy(cv); |
| cu.xtr_D(); |
| cv.copy(t); |
| } |
| else |
| { |
| d.fshr(1); |
| r.copy(cum2v); r.conj(); |
| t.copy(cumv); |
| t.xtr_A(cu,cv,r); |
| cum2v.copy(cumv); |
| cum2v.xtr_D(); |
| cumv.copy(t); |
| cu.xtr_D(); |
| } |
| } |
| } |
| r.copy(cv); |
| r.xtr_A(cu,cumv,cum2v); |
| for (int i=0;i<f2;i++) |
| r.xtr_D(); |
| r=r.xtr_pow(d); |
| return r; |
| } |
| } |