/* Create random BIG in portable way, one bit at a time */
public static BIG randomnum(BIG q, RAND rng)
{
DBIG d = new DBIG(0);
int i, b, j = 0, r = 0;
for (i = 0; i < 2 * ROM.MODBITS; i++)
{
if (j == 0)
{
r = rng.Byte;
}
else
{
r >>= 1;
}
b = r & 1;
d.shl(1);
d.w[0] += b; // m.inc(b);
j++;
j &= 7;
}
BIG m = d.mod(q);
return(m);
}
/* return a^2 mod m */
public static BIG modsqr(BIG a, BIG m)
{
a.mod(m);
DBIG d = sqr(a);
return(d.mod(m));
}
/* this*=c mod Modulus, where c is a small int */
public void imul(int c)
{
norm();
bool s = false;
if (c < 0)
{
c = -c;
s = true;
}
long afx = (BIG.EXCESS(x) + 1) * (c + 1) + 1;
if (c < ROM.NEXCESS && afx < ROM.FEXCESS)
{
x.imul(c);
}
else
{
if (afx < ROM.FEXCESS)
{
x.pmul(c);
}
else
{
DBIG d = x.pxmul(c);
x.copy(d.mod(p));
}
}
if (s)
{
neg();
}
norm();
}
/* return a*b mod m */
public static BIG modmul(BIG a, BIG b, BIG m)
{
a.mod(m);
b.mod(m);
DBIG d = mul(a, b);
return(d.mod(m));
}
/* convert to Montgomery n-residue form */
public void nres()
{
if (ROM.MODTYPE != ROM.PSEUDO_MERSENNE)
{
DBIG d = new DBIG(x);
d.shl(ROM.NLEN * ROM.BASEBITS);
x.copy(d.mod(p));
}
}
