\\
\\---------------------------------------------------------------------------------
\\	input: NO  -  phb()
\\---------------------------------------------------------------------------------
\\
\\ The program encrypts and decrypts a random word
\\
\\---------------------------------------------------------------------------------
\\
\\	allocatemem(1024000000);
\\
phb()={
\\
	local();
\\	
	NRAND=100000000000;
	NREX=3000;
\\
	p=randomprime(NRAND);
	q=randomprime(NRAND);
	N=p*q;
	print("\nN=",N);
	print("\np=",p,"  q=",q);
	if(p%4==1,ep=p-1,ep=p+1);
	if(q%4==1,eq=q-1,eq=q+1);
	epq=ep*eq;
	print("\nepq=",epq);
	print("\nep=",ep,"  eq=",eq);
	print("\nN%=",N%4,"  p%=",p%4,"  q%=",q%4);
	fl0=1;
	while(fl0,
		kex=random(NREX);
		if(kex<3,kex=3);
		mkex=Mod(kex,epq);
		if(gcd(kex,epq)==1,mdex=mkex^(-1);fl0=0);
	);
\\	print("\n1=",mkex*mdex,"  mkex=",mkex,"  mdex=",mdex);
\\
	cc=2;		\\cc=1,2,4,8...	
\\	D=-(2*cc*N)^2;
\\
	print("\nThe number of words generated - ? ");
	iw=input();
	kex=component(mkex,2);
	dex=component(mdex,2);
\\
	chyba=0;
	for(i=1,iw,
		w=random(N);			\\	Originally the word
		cw=moc(N,cc,w,kex);		\\	Encrypted word
		dw=moc(N,cc,cw,dex);		\\	Decrypted word
\\
\\		print(w);
\\		print(cw);
\\		print(dw);
\\		print(" ");
\\
		if(w==dw, ,chyba++);
	);
\\
	print("\n  kex=",kex);
	print("\n  dex=",dex);
	print("\nerror=",chyba);
	print(" ");
\\
	return();
\\
}
\\-------------------------------------------------------------------------------------------

\\---------------------------------------------------------------------------------
qcomp(x1,x2,N,cc)={
	local(xsuma,gc);
	xsuma=x1+x2;
	gc=gcd(xsuma,N);
	if(gc==1, ,return(-gc));
	return(((x1*x2-cc^2)/xsuma)%N);
}
\\---------------------------------------------------------------------------------
\\---------------------------------------------------------------------------------
moc(N,cc,y,ex)={
	local(i,bex,y0);
\\
	bex=binary(ex);
	y0=y;
	for(i=2,matsize(bex)[2],
		if(bex[i],
			y=qcomp(y,y,N,cc);
			if(y<0,printf("i=%5d  factorizacia-y0  %35d\n\n",i,-y);return());
			y=qcomp(y,y0,N,cc);
			if(y<0,printf("i=%5d  factorizacia-y1  %35d\n\n",i,-y);return());
		,
			y=qcomp(y,y,N,cc);
			if(y<0,printf("i=%5d  factorizacia-y2  %35d\n\n",i,-y);return());
		);
	);
\\
	return(y);
}
\\---------------------------------------------------------------------------------