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package org.spongycastle.crypto.modes.gcm;
import org.spongycastle.util.Arrays;
public class BasicGCMExponentiator implements GCMExponentiator
{
private int[] x;
public void init(byte[] x)
{
this.x = GCMUtil.asInts(x);
}
public void exponentiateX(long pow, byte[] output)
{
// Initial value is little-endian 1
int[] y = GCMUtil.oneAsInts();
if (pow > 0)
{
int[] powX = Arrays.clone(x);
do
{
if ((pow & 1L) != 0)
{
GCMUtil.multiply(y, powX);
}
GCMUtil.multiply(powX, powX);
pow >>>= 1;
}
while (pow > 0);
}
GCMUtil.asBytes(y, output);
}
}
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