GlvMultiplier.cs missed in last commit

1 files changed, 40 insertions, 0 deletions

diff --git a/crypto/src/math/ec/multiplier/GlvMultiplier.cs b/crypto/src/math/ec/multiplier/GlvMultiplier.cs
new file mode 100644
index 000000000..f19049474
--- /dev/null
+++ b/crypto/src/math/ec/multiplier/GlvMultiplier.cs
@@ -0,0 +1,40 @@
+using System;
+
+using Org.BouncyCastle.Math.EC.Endo;
+
+namespace Org.BouncyCastle.Math.EC.Multiplier
+{
+    public class GlvMultiplier
+        :   AbstractECMultiplier
+    {
+        protected readonly ECCurve curve;
+        protected readonly GlvEndomorphism glvEndomorphism;
+
+        public GlvMultiplier(ECCurve curve, GlvEndomorphism glvEndomorphism)
+        {
+            if (curve == null || curve.Order == null)
+                throw new ArgumentException("Need curve with known group order", "curve");
+
+            this.curve = curve;
+            this.glvEndomorphism = glvEndomorphism;
+        }
+
+        protected override ECPoint MultiplyPositive(ECPoint p, BigInteger k)
+        {
+            if (!curve.Equals(p.Curve))
+                throw new InvalidOperationException();
+
+            BigInteger n = p.Curve.Order;
+            BigInteger[] ab = glvEndomorphism.DecomposeScalar(k.Mod(n));
+            BigInteger a = ab[0], b = ab[1];
+
+            ECPointMap pointMap = glvEndomorphism.PointMap;
+            if (glvEndomorphism.HasEfficientPointMap)
+            {
+                return ECAlgorithms.ImplShamirsTrickWNaf(p, a, pointMap, b);
+            }
+
+            return ECAlgorithms.ImplShamirsTrickWNaf(p, a, pointMap.Map(p), b);
+        }
+    }
+}