1 files changed, 56 insertions, 0 deletions
diff --git a/libraries/spongycastle/prov/src/main/java/org/spongycastle/jce/ECPointUtil.java b/libraries/spongycastle/prov/src/main/java/org/spongycastle/jce/ECPointUtil.java
new file mode 100644
index 000000000..fa9fa62fb
--- /dev/null
+++ b/libraries/spongycastle/prov/src/main/java/org/spongycastle/jce/ECPointUtil.java
@@ -0,0 +1,56 @@
+package org.spongycastle.jce;
+
+import java.security.spec.ECFieldF2m;
+import java.security.spec.ECFieldFp;
+import java.security.spec.ECPoint;
+import java.security.spec.EllipticCurve;
+
+import org.spongycastle.math.ec.ECCurve;
+
+/**
+ * Utility class for handling EC point decoding.
+ */
+public class ECPointUtil
+{
+    /**
+     * Decode a point on this curve which has been encoded using point
+     * compression (X9.62 s 4.2.1 and 4.2.2) or regular encoding.
+     * 
+     * @param curve
+     *            The elliptic curve.
+     * @param encoded
+     *            The encoded point.
+     * @return the decoded point.
+     */
+    public static ECPoint decodePoint(
+       EllipticCurve curve, 
+       byte[] encoded)
+    {
+        ECCurve c = null;
+        
+        if (curve.getField() instanceof ECFieldFp)
+        {
+            c = new ECCurve.Fp(
+                    ((ECFieldFp)curve.getField()).getP(), curve.getA(), curve.getB());
+        }
+        else
+        {
+            int k[] = ((ECFieldF2m)curve.getField()).getMidTermsOfReductionPolynomial();
+            
+            if (k.length == 3)
+            {
+                c = new ECCurve.F2m(
+                        ((ECFieldF2m)curve.getField()).getM(), k[2], k[1], k[0], curve.getA(), curve.getB());
+            }
+            else
+            {
+                c = new ECCurve.F2m(
+                        ((ECFieldF2m)curve.getField()).getM(), k[0], curve.getA(), curve.getB());
+            }
+        }
+        
+        org.spongycastle.math.ec.ECPoint p = c.decodePoint(encoded);
+
+        return new ECPoint(p.getAffineXCoord().toBigInteger(), p.getAffineYCoord().toBigInteger());
+    }
+}