Initial Commit

iTechSharp/srcbc/asn1/x9/X9FieldElement.cs

@@ -0,0 +1,69 @@
+using System;
+
+using Org.BouncyCastle.Math;
+using Org.BouncyCastle.Math.EC;
+
+namespace Org.BouncyCastle.Asn1.X9
+{
+    /**
+     * class for processing an FieldElement as a Der object.
+     */
+    public class X9FieldElement
+        : Asn1Encodable
+    {
+		private ECFieldElement f;
+
+		public X9FieldElement(
+			ECFieldElement f)
+		{
+			this.f = f;
+		}
+
+		public X9FieldElement(
+			BigInteger		p,
+			Asn1OctetString	s)
+			: this(new FpFieldElement(p, new BigInteger(1, s.GetOctets())))
+		{
+		}
+
+		public X9FieldElement(
+			int				m,
+			int				k1,
+			int				k2,
+			int				k3,
+			Asn1OctetString	s)
+			: this(new F2mFieldElement(m, k1, k2, k3, new BigInteger(1, s.GetOctets())))
+		{
+		}
+
+		public ECFieldElement Value
+        {
+            get { 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>
+		 * </p>
+		 */
+		public override Asn1Object ToAsn1Object()
+		{
+			int byteCount = X9IntegerConverter.GetByteLength(f);
+			byte[] paddedBigInteger = X9IntegerConverter.IntegerToBytes(f.ToBigInteger(), byteCount);
+
+			return new DerOctetString(paddedBigInteger);
+		}
+    }
+}