1 files changed, 24 insertions, 0 deletions
diff --git a/bcprov/src/main/java/org/bouncycastle/math/ec/DoubleAddMultiplier.java b/bcprov/src/main/java/org/bouncycastle/math/ec/DoubleAddMultiplier.java
new file mode 100644
index 0000000..aae2e00
--- /dev/null
+++ b/bcprov/src/main/java/org/bouncycastle/math/ec/DoubleAddMultiplier.java
@@ -0,0 +1,24 @@
+package org.bouncycastle.math.ec;
+
+import java.math.BigInteger;
+
+public class DoubleAddMultiplier extends AbstractECMultiplier
+{
+    /**
+     * Joye's double-add algorithm.
+     */
+    protected ECPoint multiplyPositive(ECPoint p, BigInteger k)
+    {
+        ECPoint[] R = new ECPoint[]{ p.getCurve().getInfinity(), p };
+
+        int n = k.bitLength();
+        for (int i = 0; i < n; ++i)
+        {
+            int b = k.testBit(i) ? 1 : 0;
+            int bp = 1 - b;
+            R[bp] = R[bp].twicePlus(R[b]);
+        }
+
+        return R[0];
+    }
+}