Add squareN to perform repeated modular squaring

2 files changed, 30 insertions, 0 deletions

diff --git a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256K1Field.java b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256K1Field.java
index 9299dcd9..3d1c45e1 100644
--- a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256K1Field.java
+++ b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256K1Field.java
@@ -113,6 +113,21 @@ public class SecP256K1Field
         reduce(tt, z);
     }
 
+    public static void squareN(int[] x, int n, int[] z)
+    {
+//        assert n > 0;
+
+        int[] tt = Nat256.createExt();
+        Nat256.square(x, tt);
+        reduce(tt, z);
+
+        while (--n > 0)
+        {
+            Nat256.square(z, tt);
+            reduce(tt, z);
+        }
+    }
+
     public static void subtract(int[] x, int[] y, int[] z)
     {
         int c = Nat256.sub(x, y, z);
diff --git a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256R1Field.java b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256R1Field.java
index 15412efe..94bbef69 100644
--- a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256R1Field.java
+++ b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256R1Field.java
@@ -146,6 +146,21 @@ public class SecP256R1Field
         reduce(tt, z);
     }
 
+    public static void squareN(int[] x, int n, int[] z)
+    {
+//        assert n > 0;
+
+        int[] tt = Nat256.createExt();
+        Nat256.square(x, tt);
+        reduce(tt, z);
+
+        while (--n > 0)
+        {
+            Nat256.square(z, tt);
+            reduce(tt, z);
+        }
+    }
+
     public static void subtract(int[] x, int[] y, int[] z)
     {
         int c = Nat256.sub(x, y, z);