correctly encode EC points to bytes

Author: kares

src/main/java/org/jruby/ext/openssl/PKeyEC.java

@@ -907,15 +907,31 @@ static byte[] encode(final ECPublicKey pubKey) {
     }
 
     private static byte[] encode(final int bitLength, final ECPoint point) {
-        int keyLengthBytes = bitLength / 8;
-        byte[] encoded = new byte[1 + 2 * keyLengthBytes];
+        if ( point == ECPoint.POINT_INFINITY )  return new byte[1];
+
+        final int bytesLength = (bitLength + 7) / 8;
+        byte[] encoded = new byte[1 + bytesLength + bytesLength];
 
         encoded[0] = 0x04;
 
-        System.arraycopy(point.getAffineX().toByteArray(), 0, encoded, 1, keyLengthBytes);
-        System.arraycopy(point.getAffineY().toByteArray(), 0, encoded, 1 + keyLengthBytes, keyLengthBytes);
+        addIntBytes(point.getAffineX(), bytesLength, encoded, 1);
+        addIntBytes(point.getAffineY(), bytesLength, encoded, 1 + bytesLength);
 
         return encoded;
     }
 
+    private static void addIntBytes(BigInteger i, final int length, final byte[] dest, final int destOffset) {
+       final byte[] bytes = i.toByteArray();
+
+       if (length < bytes.length) {
+           System.arraycopy(bytes, bytes.length - length, dest, destOffset, length);
+        }
+        else if (length > bytes.length) {
+            System.arraycopy(bytes, 0, dest, destOffset + (length - bytes.length), bytes.length);
+        }
+        else {
+            System.arraycopy(bytes, 0, dest, destOffset, length);
+        }
+    }
+
 }

src/test/ruby/ec/test_ec.rb

@@ -51,6 +51,15 @@ def test_read_pem2
     #puts signature.inspect
   end
 
+  def test_point
+    group = OpenSSL::PKey::EC::Group.new('prime256v1')
+    client_public_key_bn = OpenSSL::BN.new('58089019511196532477248433747314139754458690644712400444716868601190212265537817278966641566813745621284958192417192818318052462970895792919572995957754854')
+
+    binary = "\x04U\x1D6|\xA9\x14\eC\x13\x99b\x96\x9B\x94f\x8F\xB0o\xE2\xD3\xBC%\x8E\xE0Xn\xF2|R\x99b\xBD\xBFB\x8FS\xCF\x13\x7F\x8C\x03N\x96\x9D&\xB2\xE1\xBDQ\b\xCE\x94!s\x06.\xC5?\x96\xC7q\xDA\x8B\xE6"
+    client_public_key = OpenSSL::PKey::EC::Point.new(group, client_public_key_bn)
+    assert_equal binary, client_public_key.to_bn.to_s(2)
+  end
+
   require File.expand_path('base64.rb', File.dirname(__FILE__))
 
   def test_encrypt