1 files changed, 31 insertions, 0 deletions
diff --git a/libraries/spongycastle/core/src/main/java/org/spongycastle/math/ec/NafR2LMultiplier.java b/libraries/spongycastle/core/src/main/java/org/spongycastle/math/ec/NafR2LMultiplier.java
new file mode 100644
index 000000000..78aecb025
--- /dev/null
+++ b/libraries/spongycastle/core/src/main/java/org/spongycastle/math/ec/NafR2LMultiplier.java
@@ -0,0 +1,31 @@
+package org.spongycastle.math.ec;
+
+import java.math.BigInteger;
+
+/**
+ * Class implementing the NAF (Non-Adjacent Form) multiplication algorithm (right-to-left).
+ */
+public class NafR2LMultiplier extends AbstractECMultiplier
+{
+    protected ECPoint multiplyPositive(ECPoint p, BigInteger k)
+    {
+        int[] naf = WNafUtil.generateCompactNaf(k);
+
+        ECPoint R0 = p.getCurve().getInfinity(), R1 = p;
+
+        int zeroes = 0;
+        for (int i = 0; i < naf.length; ++i)
+        {
+            int ni = naf[i];
+            int digit = ni >> 16;
+            zeroes += ni & 0xFFFF;
+
+            R1 = R1.timesPow2(zeroes);
+            R0 = R0.add(digit < 0 ? R1.negate() : R1);
+
+            zeroes = 1;
+        }
+
+        return R0;
+    }
+}