How to use

salsaCore

method

in

org.spongycastle.crypto.engines.Salsa20Engine

private void generateKeyStream(byte[] output)
{
  salsaCore(20, engineState, x);
  Pack.intToLittleEndian(x, output, 0);
}

protected void generateKeyStream(byte[] output)
{
  salsaCore(rounds, engineState, x);
  Pack.intToLittleEndian(x, output, 0);
}

private static void blockMix(int[] B, int[] X1, int[] X2, int[] Y, int r) {
  System.arraycopy(B, B.length - 16, X1, 0, 16);
  int BOff = 0, YOff = 0, halfLen = B.length >>> 1;
  for (int i = 2 * r; i > 0; --i) {
    xor(X1, B, BOff, X2);
    Salsa20Engine.salsaCore(8, X2, X1);
    System.arraycopy(X1, 0, Y, YOff, 16);
    YOff = halfLen + BOff - YOff;
    BOff += 16;
  }
  System.arraycopy(Y, 0, B, 0, Y.length);
}

private static void BlockMix(int[] B, int[] X1, int[] X2, int[] Y, int r)
{
  System.arraycopy(B, B.length - 16, X1, 0, 16);
  int BOff = 0, YOff = 0, halfLen = B.length >>> 1;
  for (int i = 2 * r; i > 0; --i)
  {
    Xor(X1, B, BOff, X2);
    Salsa20Engine.salsaCore(8, X2, X1);
    System.arraycopy(X1, 0, Y, YOff, 16);
    YOff = halfLen + BOff - YOff;
    BOff += 16;
  }
  System.arraycopy(Y, 0, B, 0, Y.length);
}

private static void BlockMix(int[] B, int[] X1, int[] X2, int[] Y, int r)
{
  System.arraycopy(B, B.length - 16, X1, 0, 16);
  int BOff = 0, YOff = 0, halfLen = B.length >>> 1;
  for (int i = 2 * r; i > 0; --i)
  {
    Xor(X1, B, BOff, X2);
    Salsa20Engine.salsaCore(8, X2, X1);
    System.arraycopy(X1, 0, Y, YOff, 16);
    YOff = halfLen + BOff - YOff;
    BOff += 16;
  }
  System.arraycopy(Y, 0, B, 0, Y.length);
}