diff --git a/ndn-cpp/encoding/binary-xml-wire-format.hpp b/ndn-cpp/encoding/binary-xml-wire-format.hpp
index c327d17..7266957 100644
--- a/ndn-cpp/encoding/binary-xml-wire-format.hpp
+++ b/ndn-cpp/encoding/binary-xml-wire-format.hpp
@@ -10,13 +10,41 @@
 
 namespace ndn {
 
+/**
+ * A BinaryXmlWireFormat extends WireFormat to override its virtual methods to implement encoding and decoding
+ * using binary XML.
+ */
 class BinaryXmlWireFormat : public WireFormat {
 public:
   virtual ptr_lib::shared_ptr<std::vector<unsigned char> > encodeInterest(const Interest &interest);
   virtual void decodeInterest(Interest &interest, const unsigned char *input, unsigned int inputLength);
 
-  virtual ptr_lib::shared_ptr<std::vector<unsigned char> > encodeData(const Data &data);
-  virtual void decodeData(Data &data, const unsigned char *input, unsigned int inputLength);
+  /**
+   * Encode data with binary XML and return the encoding.
+   * @param data The Data object to encode.
+   * @param signedFieldsBeginOffset Return the offset in the encoding of the beginning of the fields which are signed.
+   * If you are not encoding in order to sign, you can call encodeData(const Data &data) to ignore this returned value.
+   * @param signedFieldsEndOffset Return the offset in the encoding of the end of the fields which are signed.
+   * If you are not encoding in order to sign, you can call encodeData(const Data &data) to ignore this returned value.
+   * @return A shared_ptr with the vector<unsigned char> containing the encoding.
+   */
+  virtual ptr_lib::shared_ptr<std::vector<unsigned char> > encodeData
+    (const Data &data, unsigned int *signedFieldsBeginOffset, unsigned int *signedFieldsEndOffset);
+  
+  /**
+   * Decode input as a data packet in binary XML and set the fields in the data object.
+   * @param data The Data object whose fields are updated.
+   * @param input A pointer to the input buffer to decode.
+   * @param inputLength The number of bytes in input.
+   * @param signedFieldsBeginOffset Return the offset in the input buffer of the beginning of the fields which are signed.
+   * If you are not decoding in order to verify, you can call 
+   * decodeData(Data &data, const unsigned char *input, unsigned int inputLength) to ignore this returned value.
+   * @param signedFieldsEndOffset Return the offset in the input buffer of the end of the fields which are signed.
+   * If you are not decoding in order to verify, you can call 
+   * decodeData(Data &data, const unsigned char *input, unsigned int inputLength) to ignore this returned value.
+   */  
+  virtual void decodeData
+    (Data &data, const unsigned char *input, unsigned int inputLength, unsigned int *signedFieldsBeginOffset, unsigned int *signedFieldsEndOffset);
 };
   
 }