Adding EncryptedContent class, for group-based encryption protocol

Change-Id: I661e110db8ca91420359d070c1bb74464117b8d9
diff --git a/src/encrypted-content.cpp b/src/encrypted-content.cpp
new file mode 100644
index 0000000..0a7c9e1
--- /dev/null
+++ b/src/encrypted-content.cpp
@@ -0,0 +1,162 @@
+#include "encrypted-content.hpp"
+#include <ndn-cxx/encoding/block-helpers.hpp>
+#include <ndn-cxx/util/concepts.hpp>
+
+#include <boost/lexical_cast.hpp>
+
+namespace ndn {
+namespace gep {
+
+BOOST_CONCEPT_ASSERT((boost::EqualityComparable<EncryptedContent>));
+BOOST_CONCEPT_ASSERT((WireEncodable<EncryptedContent>));
+BOOST_CONCEPT_ASSERT((WireDecodable<EncryptedContent>));
+static_assert(std::is_base_of<ndn::tlv::Error, EncryptedContent::Error>::value,
+              "EncryptedContent::Error must inherit from tlv::Error");
+
+EncryptedContent::EncryptedContent()
+  : m_type(-1)
+  , m_hasKeyLocator(false)
+{
+}
+
+EncryptedContent::EncryptedContent(tlv::AlgorithmTypeValue type, const KeyLocator& keyLocator, const ConstBufferPtr& payload)
+  : m_type(type)
+  , m_hasKeyLocator(true)
+  , m_keyLocator(keyLocator)
+  , m_payload(payload)
+{
+}
+
+EncryptedContent::EncryptedContent(const Block& block)
+{
+  wireDecode(block);
+}
+
+void
+EncryptedContent::setAlgorithmType(tlv::AlgorithmTypeValue type)
+{
+  m_wire.reset();
+  m_type = type;
+}
+
+void
+EncryptedContent::setKeyLocator(const KeyLocator& keyLocator)
+{
+  m_wire.reset();
+  m_keyLocator = keyLocator;
+  m_hasKeyLocator = true;
+}
+
+const KeyLocator&
+EncryptedContent::getKeyLocator() const
+{
+  if (m_hasKeyLocator)
+    return m_keyLocator;
+  else
+    throw Error("KeyLocator does not exist");
+}
+
+void
+EncryptedContent::setPayload(const ConstBufferPtr& payload)
+{
+  m_wire.reset();
+  m_payload = payload;
+}
+
+const ConstBufferPtr
+EncryptedContent::getPayload() const
+{
+  return m_payload;
+}
+
+template<encoding::Tag TAG>
+size_t
+EncryptedContent::wireEncode(EncodingImpl<TAG>& block) const
+{
+  size_t totalLength = 0;
+
+  totalLength += block.appendByteArrayBlock(tlv::EncryptedPayload, m_payload->buf(), m_payload->size());
+
+  if (m_type != -1)
+    totalLength += prependNonNegativeIntegerBlock(block, tlv::EncryptionAlgorithm, m_type);
+  else
+    throw Error("EncryptedContent does not have an encryption algorithm");
+
+  if (m_hasKeyLocator)
+    totalLength += m_keyLocator.wireEncode(block);
+  else
+    throw Error("EncryptedContent does not have key locator");
+
+  totalLength += block.prependVarNumber(totalLength);
+  totalLength += block.prependVarNumber(tlv::EncryptedContent);
+  return totalLength;
+}
+
+const Block&
+EncryptedContent::wireEncode() const
+{
+  if (m_wire.hasWire())
+    return m_wire;
+
+  EncodingEstimator estimator;
+  size_t estimatedSize = wireEncode(estimator);
+
+  EncodingBuffer buffer(estimatedSize, 0);
+  wireEncode(buffer);
+
+  m_wire = buffer.block();
+  return m_wire;
+}
+
+void
+EncryptedContent::wireDecode(const Block& wire)
+{
+  if (!wire.hasWire()) {
+    throw Error("The supplied block does not contain wire format");
+  }
+
+  m_hasKeyLocator = false;
+
+  m_wire = wire;
+  m_wire.parse();
+
+  if (m_wire.type() != tlv::EncryptedContent)
+    throw Error("Unexpected TLV type when decoding Name");
+
+  Block::element_const_iterator it = m_wire.elements_begin();
+
+  if (it != m_wire.elements_end() && it->type() == ndn::tlv::KeyLocator) {
+    m_keyLocator.wireDecode(*it);
+    m_hasKeyLocator = true;
+    it++;
+  }
+  else
+    throw Error("EncryptedContent does not have key locator");
+
+  if (it != m_wire.elements_end() && it->type() == tlv::EncryptionAlgorithm) {
+    m_type = readNonNegativeInteger(*it);
+    it++;
+  }
+  else
+    throw Error("EncryptedContent does not have encryption algorithm");
+
+  if (it != m_wire.elements_end() && it->type() == tlv::EncryptedPayload) {
+    m_payload = make_shared<Buffer>(it->value_begin(),it->value_end());
+    it++;
+  }
+  else
+    throw Error("EncryptedContent has missing payload");
+
+  if (it != m_wire.elements_end()) {
+    throw Error("EncryptedContent has extraneous sub-TLVs");
+  }
+}
+
+bool
+EncryptedContent::operator==(const EncryptedContent& rhs) const
+{
+  return (wireEncode() == rhs.wireEncode());
+}
+
+} // namespace gep
+} // namespace ndn