diff --git a/ndn-cpp/security/identity/private-key-storage.cpp b/ndn-cpp/security/identity/private-key-storage.cpp
index 4f2d0aa..8ed3cb3 100644
--- a/ndn-cpp/security/identity/private-key-storage.cpp
+++ b/ndn-cpp/security/identity/private-key-storage.cpp
@@ -1,8 +1,13 @@
 /**
+ * @author: Yingdi Yu <yingdi@cs.ucla.edu>
  * @author: Jeff Thompson
  * See COPYING for copyright and distribution information.
  */
 
+#if 1
+#include <stdexcept>
+#include "../../c/util/crypto.h"
+#endif
 #include "private-key-storage.hpp"
 
 using namespace std;
@@ -13,11 +18,68 @@
 {
 }
 
+#if 1
+static unsigned char DEFAULT_PRIVATE_KEY_DER[] = {
+0x30, 0x82, 0x02, 0x5d, 0x02, 0x01, 0x00, 0x02, 0x81, 0x81, 0x00, 0xe1, 0x7d, 0x30, 0xa7, 0xd8, 0x28, 0xab, 0x1b, 0x84,
+0x0b, 0x17, 0x54, 0x2d, 0xca, 0xf6, 0x20, 0x7a, 0xfd, 0x22, 0x1e, 0x08, 0x6b, 0x2a, 0x60, 0xd1, 0x6c, 0xb7, 0xf5, 0x44,
+0x48, 0xba, 0x9f, 0x3f, 0x08, 0xbc, 0xd0, 0x99, 0xdb, 0x21, 0xdd, 0x16, 0x2a, 0x77, 0x9e, 0x61, 0xaa, 0x89, 0xee, 0xe5,
+0x54, 0xd3, 0xa4, 0x7d, 0xe2, 0x30, 0xbc, 0x7a, 0xc5, 0x90, 0xd5, 0x24, 0x06, 0x7c, 0x38, 0x98, 0xbb, 0xa6, 0xf5, 0xdc,
+0x43, 0x60, 0xb8, 0x45, 0xed, 0xa4, 0x8c, 0xbd, 0x9c, 0xf1, 0x26, 0xa7, 0x23, 0x44, 0x5f, 0x0e, 0x19, 0x52, 0xd7, 0x32,
+0x5a, 0x75, 0xfa, 0xf5, 0x56, 0x14, 0x4f, 0x9a, 0x98, 0xaf, 0x71, 0x86, 0xb0, 0x27, 0x86, 0x85, 0xb8, 0xe2, 0xc0, 0x8b,
+0xea, 0x87, 0x17, 0x1b, 0x4d, 0xee, 0x58, 0x5c, 0x18, 0x28, 0x29, 0x5b, 0x53, 0x95, 0xeb, 0x4a, 0x17, 0x77, 0x9f, 0x02,
+0x03, 0x01, 0x00, 0x01, 0x02, 0x81, 0x80, 0x1a, 0x4b, 0xfa, 0x4f, 0xa8, 0xc2, 0xdd, 0x69, 0xa1, 0x15, 0x96, 0x0b, 0xe8,
+0x27, 0x42, 0x5a, 0xf9, 0x5c, 0xea, 0x0c, 0xac, 0x98, 0xaa, 0xe1, 0x8d, 0xaa, 0xeb, 0x2d, 0x3c, 0x60, 0x6a, 0xfb, 0x45,
+0x63, 0xa4, 0x79, 0x83, 0x67, 0xed, 0xe4, 0x15, 0xc0, 0xb0, 0x20, 0x95, 0x6d, 0x49, 0x16, 0xc6, 0x42, 0x05, 0x48, 0xaa,
+0xb1, 0xa5, 0x53, 0x65, 0xd2, 0x02, 0x99, 0x08, 0xd1, 0x84, 0xcc, 0xf0, 0xcd, 0xea, 0x61, 0xc9, 0x39, 0x02, 0x3f, 0x87,
+0x4a, 0xe5, 0xc4, 0xd2, 0x07, 0x02, 0xe1, 0x9f, 0xa0, 0x06, 0xc2, 0xcc, 0x02, 0xe7, 0xaa, 0x6c, 0x99, 0x8a, 0xf8, 0x49,
+0x00, 0xf1, 0xa2, 0x8c, 0x0c, 0x8a, 0xb9, 0x4f, 0x6d, 0x73, 0x3b, 0x2c, 0xb7, 0x9f, 0x8a, 0xa6, 0x7f, 0x9b, 0x9f, 0xb7,
+0xa1, 0xcc, 0x74, 0x2e, 0x8f, 0xb8, 0xb0, 0x26, 0x89, 0xd2, 0xe5, 0x66, 0xe8, 0x8e, 0xa1, 0x02, 0x41, 0x00, 0xfc, 0xe7,
+0x52, 0xbc, 0x4e, 0x95, 0xb6, 0x1a, 0xb4, 0x62, 0xcc, 0xd8, 0x06, 0xe1, 0xdc, 0x7a, 0xa2, 0xb6, 0x71, 0x01, 0xaa, 0x27,
+0xfc, 0x99, 0xe5, 0xf2, 0x54, 0xbb, 0xb2, 0x85, 0xe1, 0x96, 0x54, 0x2d, 0xcb, 0xba, 0x86, 0xfa, 0x80, 0xdf, 0xcf, 0x39,
+0xe6, 0x74, 0xcb, 0x22, 0xce, 0x70, 0xaa, 0x10, 0x00, 0x73, 0x1d, 0x45, 0x0a, 0x39, 0x51, 0x84, 0xf5, 0x15, 0x8f, 0x37,
+0x76, 0x91, 0x02, 0x41, 0x00, 0xe4, 0x3f, 0xf0, 0xf4, 0xde, 0x79, 0x77, 0x48, 0x9b, 0x9c, 0x28, 0x45, 0x26, 0x57, 0x3c,
+0x71, 0x40, 0x28, 0x6a, 0xa1, 0xfe, 0xc3, 0xe5, 0x37, 0xa1, 0x03, 0xf6, 0x2d, 0xbe, 0x80, 0x64, 0x72, 0x69, 0x2e, 0x9b,
+0x4d, 0xe3, 0x2e, 0x1b, 0xfe, 0xe7, 0xf9, 0x77, 0x8c, 0x18, 0x53, 0x9f, 0xe2, 0xfe, 0x00, 0xbb, 0x49, 0x20, 0x47, 0xdf,
+0x01, 0x61, 0x87, 0xd6, 0xe3, 0x44, 0xb5, 0x03, 0x2f, 0x02, 0x40, 0x54, 0xec, 0x7c, 0xbc, 0xdd, 0x0a, 0xaa, 0xde, 0xe6,
+0xc9, 0xf2, 0x8d, 0x6c, 0x2a, 0x35, 0xf6, 0x3c, 0x63, 0x55, 0x29, 0x40, 0xf1, 0x32, 0x82, 0x9f, 0x53, 0xb3, 0x9e, 0x5f,
+0xc1, 0x53, 0x52, 0x3e, 0xac, 0x2e, 0x28, 0x51, 0xa1, 0x16, 0xdb, 0x90, 0xe3, 0x99, 0x7e, 0x88, 0xa4, 0x04, 0x7c, 0x92,
+0xae, 0xd2, 0xe7, 0xd4, 0xe1, 0x55, 0x20, 0x90, 0x3e, 0x3c, 0x6a, 0x63, 0xf0, 0x34, 0xf1, 0x02, 0x41, 0x00, 0x84, 0x5a,
+0x17, 0x6c, 0xc6, 0x3c, 0x84, 0xd0, 0x93, 0x7a, 0xff, 0x56, 0xe9, 0x9e, 0x98, 0x2b, 0xcb, 0x5a, 0x24, 0x4a, 0xff, 0x21,
+0xb4, 0x9e, 0x87, 0x3d, 0x76, 0xd8, 0x9b, 0xa8, 0x73, 0x96, 0x6c, 0x2b, 0x5c, 0x5e, 0xd3, 0xa6, 0xff, 0x10, 0xd6, 0x8e,
+0xaf, 0xa5, 0x8a, 0xcd, 0xa2, 0xde, 0xcb, 0x0e, 0xbd, 0x8a, 0xef, 0xae, 0xfd, 0x3f, 0x1d, 0xc0, 0xd8, 0xf8, 0x3b, 0xf5,
+0x02, 0x7d, 0x02, 0x41, 0x00, 0x8b, 0x26, 0xd3, 0x2c, 0x7d, 0x28, 0x38, 0x92, 0xf1, 0xbf, 0x15, 0x16, 0x39, 0x50, 0xc8,
+0x6d, 0x32, 0xec, 0x28, 0xf2, 0x8b, 0xd8, 0x70, 0xc5, 0xed, 0xe1, 0x7b, 0xff, 0x2d, 0x66, 0x8c, 0x86, 0x77, 0x43, 0xeb,
+0xb6, 0xf6, 0x50, 0x66, 0xb0, 0x40, 0x24, 0x6a, 0xaf, 0x98, 0x21, 0x45, 0x30, 0x01, 0x59, 0xd0, 0xc3, 0xfc, 0x7b, 0xae,
+0x30, 0x18, 0xeb, 0x90, 0xfb, 0x17, 0xd3, 0xce, 0xb5
+};
+#endif
+
 // TODO: Move to subclass.
 Blob 
 PrivateKeyStorage::sign(const Blob& blob, const string& keyName, DigestAlgorithm digestAlgorithm)
 {
-  return Blob();
+#if 1
+  if (digestAlgorithm != DIGEST_ALGORITHM_SHA256)
+    return Blob();
+
+  unsigned char digest[SHA256_DIGEST_LENGTH];
+  ndn_digestSha256(blob.buf(), blob.size(), digest);
+  // TODO: use RSA_size to get the proper size of the signature buffer.
+  unsigned char signatureBits[1000];
+  unsigned int signatureBitsLength;
+  // Use a temporary pointer since d2i updates it.
+  const unsigned char *derPointer = DEFAULT_PRIVATE_KEY_DER;
+  RSA *privateKey = d2i_RSAPrivateKey(NULL, &derPointer, sizeof(DEFAULT_PRIVATE_KEY_DER));
+  if (!privateKey)
+    throw std::runtime_error("Error decoding private key in d2i_RSAPrivateKey");
+  int success = RSA_sign(NID_sha256, digest, sizeof(digest), signatureBits, &signatureBitsLength, privateKey);
+  // Free the private key before checking for success.
+  RSA_free(privateKey);
+  if (!success)
+    throw std::runtime_error("Error in RSA_sign");
+  
+  return Blob(signatureBits, signatureBitsLength);
+#endif
 }
 
 }