Added BinaryXMLKey
diff --git a/ndn-cpp/c/encoding/BinaryXMLKey.c b/ndn-cpp/c/encoding/BinaryXMLKey.c
new file mode 100644
index 0000000..8d51b4d
--- /dev/null
+++ b/ndn-cpp/c/encoding/BinaryXMLKey.c
@@ -0,0 +1,98 @@
+/**
+ * @author: Jeff Thompson
+ * Derived from Key.js by Meki Cheraoui.
+ * See COPYING for copyright and distribution information.
+ */
+
+#include "BinaryXML.h"
+#include "BinaryXMLKey.h"
+
+ndn_Error ndn_encodeBinaryXMLKeyLocator(struct ndn_KeyLocator *keyLocator, struct ndn_BinaryXMLEncoder *encoder)
+{
+  if (keyLocator->type < 0)
+    return 0;
+
+  ndn_Error error;
+  if (error = ndn_BinaryXMLEncoder_writeElementStartDTag(encoder, ndn_BinaryXML_DTag_KeyLocator))
+    return error;
+
+  if (keyLocator->type == ndn_KeyLocatorType_KEY) {
+    if (error = ndn_BinaryXMLEncoder_writeBlobDTagElement
+        (encoder, ndn_BinaryXML_DTag_Key, keyLocator->keyOrCertificate, keyLocator->keyOrCertificateLength))
+      return error;    
+  }
+  else if (keyLocator->type == ndn_KeyLocatorType_CERTIFICATE) {
+    if (error = ndn_BinaryXMLEncoder_writeBlobDTagElement
+        (encoder, ndn_BinaryXML_DTag_Certificate, keyLocator->keyOrCertificate, keyLocator->keyOrCertificateLength))
+      return error;    
+  }
+  else if (keyLocator->type == ndn_KeyLocatorType_KEYNAME) {
+    // TODO: Implement keyName
+  }
+  else
+    return NDN_ERROR_unrecognized_ndn_KeyLocatorType;
+  
+	if (error = ndn_BinaryXMLEncoder_writeElementClose(encoder))
+    return error;
+  
+  return 0;
+}
+
+ndn_Error ndn_decodeBinaryXMLKeyLocator(struct ndn_KeyLocator *keyLocator, struct ndn_BinaryXMLDecoder *decoder)
+{
+  ndn_Error error;
+  if (error = ndn_BinaryXMLDecoder_readElementStartDTag(decoder, ndn_BinaryXML_DTag_KeyLocator))
+    return error;
+
+  int gotExpectedTag;
+  if (error = ndn_BinaryXMLDecoder_peekDTag(decoder, ndn_BinaryXML_DTag_Key, &gotExpectedTag))
+    return error;
+  if (gotExpectedTag) {
+    keyLocator->type = ndn_KeyLocatorType_KEY;
+    
+    if (error = ndn_BinaryXMLDecoder_readBinaryDTagElement
+        (decoder, ndn_BinaryXML_DTag_Key, 0, &keyLocator->keyOrCertificate, &keyLocator->keyOrCertificateLength))
+      return error;
+  }
+  else {
+    if (error = ndn_BinaryXMLDecoder_peekDTag(decoder, ndn_BinaryXML_DTag_Certificate, &gotExpectedTag))
+      return error;
+    if (gotExpectedTag) {
+      keyLocator->type = ndn_KeyLocatorType_CERTIFICATE;
+    
+      if (error = ndn_BinaryXMLDecoder_readBinaryDTagElement
+          (decoder, ndn_BinaryXML_DTag_Certificate, 0, &keyLocator->keyOrCertificate, &keyLocator->keyOrCertificateLength))
+        return error;
+    }
+    else {
+      if (error = ndn_BinaryXMLDecoder_peekDTag(decoder, ndn_BinaryXML_DTag_KeyName, &gotExpectedTag))
+        return error;
+      if (gotExpectedTag) {
+        // TODO: Implement keyName
+      }
+      else
+        return NDN_ERROR_decodeBinaryXMLKeyLocator_unrecognized_key_locator_type;
+    }
+  }
+
+  if (error = ndn_BinaryXMLDecoder_readElementClose(decoder))
+    return error;
+  
+  return 0;
+}
+
+ndn_Error ndn_decodeOptionalBinaryXMLKeyLocator(struct ndn_KeyLocator *keyLocator, struct ndn_BinaryXMLDecoder *decoder)
+{
+  int gotExpectedTag;
+  ndn_Error error; 
+  if (error = ndn_BinaryXMLDecoder_peekDTag(decoder, ndn_BinaryXML_DTag_KeyLocator, &gotExpectedTag))
+    return error;
+  if (gotExpectedTag) {
+    if (error = ndn_decodeBinaryXMLKeyLocator(keyLocator, decoder))
+      return error;
+  }
+  else
+    ndn_KeyLocator_init(keyLocator);
+  
+  return 0;
+}