1 files changed, 151 insertions, 0 deletions
diff --git a/pg/src/main/java/org/spongycastle/bcpg/ECPublicBCPGKey.java b/pg/src/main/java/org/spongycastle/bcpg/ECPublicBCPGKey.java
new file mode 100644
index 00000000..5d4e74f9
--- /dev/null
+++ b/pg/src/main/java/org/spongycastle/bcpg/ECPublicBCPGKey.java
@@ -0,0 +1,151 @@
+package org.spongycastle.bcpg;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.math.BigInteger;
+
+import org.spongycastle.asn1.ASN1ObjectIdentifier;
+import org.spongycastle.asn1.ASN1Primitive;
+import org.spongycastle.asn1.x9.ECNamedCurveTable;
+import org.spongycastle.asn1.x9.X9ECParameters;
+import org.spongycastle.crypto.ec.CustomNamedCurves;
+import org.spongycastle.math.ec.ECAlgorithms;
+import org.spongycastle.math.ec.ECPoint;
+import org.spongycastle.util.BigIntegers;
+
+/**
+ * base class for an EC Public Key.
+ */
+public abstract class ECPublicBCPGKey
+    extends BCPGObject
+    implements BCPGKey
+{
+    ASN1ObjectIdentifier oid;
+    ECPoint point;
+
+    /**
+     * @param in the stream to read the packet from.
+     */
+    protected ECPublicBCPGKey(
+        BCPGInputStream in)
+        throws IOException
+    {
+        this.oid = ASN1ObjectIdentifier.getInstance(ASN1Primitive.fromByteArray(readBytesOfEncodedLength(in)));
+        this.point = decodePoint(new MPInteger(in).getValue(), oid);
+    }
+
+    protected ECPublicBCPGKey(
+        ASN1ObjectIdentifier oid,
+        ECPoint point)
+    {
+        this.point = point.normalize();
+        this.oid = oid;
+    }
+
+    protected ECPublicBCPGKey(
+        ASN1ObjectIdentifier oid,
+        BigInteger encodedPoint)
+        throws IOException
+    {
+        this.point = decodePoint(encodedPoint, oid);
+        this.oid = oid;
+    }
+
+    /**
+     * return "PGP"
+     *
+     * @see org.spongycastle.bcpg.BCPGKey#getFormat()
+     */
+    public String getFormat()
+    {
+        return "PGP";
+    }
+
+    /**
+     * return the standard PGP encoding of the key.
+     *
+     * @see org.spongycastle.bcpg.BCPGKey#getEncoded()
+     */
+    public byte[] getEncoded()
+    {
+        try
+        {
+            ByteArrayOutputStream bOut = new ByteArrayOutputStream();
+            BCPGOutputStream pgpOut = new BCPGOutputStream(bOut);
+
+            pgpOut.writeObject(this);
+
+            return bOut.toByteArray();
+        }
+        catch (IOException e)
+        {
+            return null;
+        }
+    }
+
+    public void encode(
+        BCPGOutputStream out)
+        throws IOException
+    {
+        byte[] oid = this.oid.getEncoded();
+        out.write(oid, 1, oid.length - 1);
+
+        MPInteger point = new MPInteger(new BigInteger(1, this.point.getEncoded()));
+        out.writeObject(point);
+    }
+
+    /**
+     * @return point
+     */
+    public ECPoint getPoint()
+    {
+        return point;
+    }
+
+    /**
+     * @return oid
+     */
+    public ASN1ObjectIdentifier getCurveOID()
+    {
+        return oid;
+    }
+
+    protected static byte[] readBytesOfEncodedLength(
+        BCPGInputStream in)
+        throws IOException
+    {
+        int length = in.read();
+        if (length == 0 || length == 0xFF)
+        {
+            throw new IOException("future extensions not yet implemented.");
+        }
+
+        byte[] buffer = new byte[length + 2];
+        in.readFully(buffer, 2, buffer.length - 2);
+        buffer[0] = (byte)0x06;
+        buffer[1] = (byte)length;
+
+        return buffer;
+    }
+
+    private static ECPoint decodePoint(
+        BigInteger encodedPoint,
+        ASN1ObjectIdentifier oid)
+        throws IOException
+    {
+        X9ECParameters x9 = CustomNamedCurves.getByOID(oid);
+        if (x9 == null)
+        {
+            x9 = ECNamedCurveTable.getByOID(oid);
+            if (x9 == null)
+            {
+                throw new IOException(oid.getId() + " does not match any known curve.");
+            }
+        }
+        if (!ECAlgorithms.isFpCurve(x9.getCurve()))
+        {
+            throw new IOException("Only prime field curves are supported.");
+        }
+        return x9.getCurve().decodePoint(BigIntegers.asUnsignedByteArray(encodedPoint));
+    }
+}