1 files changed, 64 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/asn1/x9/X9FieldElement.java b/core/src/main/java/org/spongycastle/asn1/x9/X9FieldElement.java
new file mode 100644
index 00000000..dd5b4dff
--- /dev/null
+++ b/core/src/main/java/org/spongycastle/asn1/x9/X9FieldElement.java
@@ -0,0 +1,64 @@
+package org.spongycastle.asn1.x9;
+
+import java.math.BigInteger;
+
+import org.spongycastle.asn1.ASN1Object;
+import org.spongycastle.asn1.ASN1OctetString;
+import org.spongycastle.asn1.ASN1Primitive;
+import org.spongycastle.asn1.DEROctetString;
+import org.spongycastle.math.ec.ECFieldElement;
+
+/**
+ * class for processing an FieldElement as a DER object.
+ */
+public class X9FieldElement
+    extends ASN1Object
+{
+    protected ECFieldElement  f;
+    
+    private static X9IntegerConverter converter = new X9IntegerConverter();
+
+    public X9FieldElement(ECFieldElement f)
+    {
+        this.f = f;
+    }
+    
+    public X9FieldElement(BigInteger p, ASN1OctetString s)
+    {
+        this(new ECFieldElement.Fp(p, new BigInteger(1, s.getOctets())));
+    }
+    
+    public X9FieldElement(int m, int k1, int k2, int k3, ASN1OctetString s)
+    {
+        this(new ECFieldElement.F2m(m, k1, k2, k3, new BigInteger(1, s.getOctets())));
+    }
+    
+    public ECFieldElement getValue()
+    {
+        return f;
+    }
+    
+    /**
+     * Produce an object suitable for an ASN1OutputStream.
+     * <pre>
+     *  FieldElement ::= OCTET STRING
+     * </pre>
+     * <p>
+     * <ol>
+     * <li> if <i>q</i> is an odd prime then the field element is
+     * processed as an Integer and converted to an octet string
+     * according to x 9.62 4.3.1.</li>
+     * <li> if <i>q</i> is 2<sup>m</sup> then the bit string
+     * contained in the field element is converted into an octet
+     * string with the same ordering padded at the front if necessary.
+     * </li>
+     * </ol>
+     */
+    public ASN1Primitive toASN1Primitive()
+    {
+        int byteCount = converter.getByteLength(f);
+        byte[] paddedBigInteger = converter.integerToBytes(f.toBigInteger(), byteCount);
+
+        return new DEROctetString(paddedBigInteger);
+    }
+}