1 files changed, 39 insertions, 0 deletions
diff --git a/Crypto/src/math/ec/multiplier/FpNafMultiplier.cs b/Crypto/src/math/ec/multiplier/FpNafMultiplier.cs
new file mode 100644
index 000000000..f5a98501a
--- /dev/null
+++ b/Crypto/src/math/ec/multiplier/FpNafMultiplier.cs
@@ -0,0 +1,39 @@
+namespace Org.BouncyCastle.Math.EC.Multiplier
+{
+ /**
+ * Class implementing the NAF (Non-Adjacent Form) multiplication algorithm.
+ */
+ internal class FpNafMultiplier
+ : ECMultiplier
+ {
+ /**
+ * D.3.2 pg 101
+ * @see org.bouncycastle.math.ec.multiplier.ECMultiplier#multiply(org.bouncycastle.math.ec.ECPoint, java.math.BigInteger)
+ */
+ public ECPoint Multiply(ECPoint p, BigInteger k, PreCompInfo preCompInfo)
+ {
+ // TODO Probably should try to add this
+ // BigInteger e = k.Mod(n); // n == order of p
+ BigInteger e = k;
+ BigInteger h = e.Multiply(BigInteger.Three);
+
+ ECPoint neg = p.Negate();
+ ECPoint R = p;
+
+ for (int i = h.BitLength - 2; i > 0; --i)
+ {
+ R = R.Twice();
+
+ bool hBit = h.TestBit(i);
+ bool eBit = e.TestBit(i);
+
+ if (hBit != eBit)
+ {
+ R = R.Add(hBit ? p : neg);
+ }
+ }
+
+ return R;
+ }
+ }
+}
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