diff --git a/src/ndncert-common.cpp b/src/ndncert-common.cpp
index 3e31596..439b5f5 100644
--- a/src/ndncert-common.cpp
+++ b/src/ndncert-common.cpp
@@ -97,5 +97,16 @@
   return json;
 }
 
+std::string
+hexlify(const uint8_t* bytes, size_t byteLen)
+{
+  std::stringstream ss;
+  ss << std::hex;
+  for (size_t i = 0; i < byteLen; i++) {
+    ss << std::setw(2) << std::setfill('0') << (int)bytes[i];
+  }
+  return ss.str();
+}
+
 }  // namespace ndncert
 }  // namespace ndn