diff --git a/src/security/public-key.cpp b/src/security/public-key.cpp
index 801fe6c..07b8137 100644
--- a/src/security/public-key.cpp
+++ b/src/security/public-key.cpp
@@ -25,6 +25,7 @@
 #include "public-key.hpp"
 
 #include "../encoding/oid.hpp"
+#include "../util/crypto.hpp"
 #include "cryptopp.hpp"
 
 namespace ndn {
@@ -41,6 +42,22 @@
   decode(src);
 }
 
+const Block&
+PublicKey::computeDigest() const
+{
+  if (m_key.empty())
+    throw Error("Public key is empty");
+
+  if (m_digest.hasWire())
+    return m_digest;
+  else {
+    m_digest = Block(tlv::KeyDigest, crypto::sha256(m_key.buf(), m_key.size()));
+    m_digest.encode();
+    return m_digest;
+  }
+}
+
+
 void
 PublicKey::encode(CryptoPP::BufferedTransformation& out) const
 {
@@ -105,6 +122,8 @@
       m_type = KEY_TYPE_NULL;
       throw Error("PublicKey decoding error");
     }
+
+  m_digest.reset();
 }
 
 // Blob
diff --git a/src/security/public-key.hpp b/src/security/public-key.hpp
index 243bccc..e739717 100644
--- a/src/security/public-key.hpp
+++ b/src/security/public-key.hpp
@@ -29,6 +29,7 @@
 #include "../common.hpp"
 
 #include "../encoding/buffer.hpp"
+#include "../encoding/block.hpp"
 #include "security-common.hpp"
 
 namespace CryptoPP {
@@ -84,6 +85,12 @@
     return m_type;
   }
 
+  /**
+   * @return a KeyDigest block that matches this public key
+   */
+  const Block&
+  computeDigest() const;
+
   void
   encode(CryptoPP::BufferedTransformation& out) const;
 
@@ -105,6 +112,7 @@
 private:
   KeyType m_type;
   Buffer m_key;
+  mutable Block m_digest;
 };
 
 std::ostream&
diff --git a/tests/unit-tests/security/test-public-key.cpp b/tests/unit-tests/security/test-public-key.cpp
index bf0a00c..46ecfea 100644
--- a/tests/unit-tests/security/test-public-key.cpp
+++ b/tests/unit-tests/security/test-public-key.cpp
@@ -37,9 +37,26 @@
 yx/I9H/DV+AqSHCaYbB92HDcDN0kqwSnUf5H1+osE9MR5DLBLhXdSiULSgxT3Or/\
 y2QgsgUK59WrjhlVMPEiHHRs15NZJbL1uQFXjgScdEarohcY3dilqotineFZCeN8\
 DwIDAQAB");
+
+const uint8_t RSA_DER_KEY_DIGEST[] = {
+  0x1d, 0x20,
+    0x58, 0x72, 0x4c, 0xf7, 0x36, 0x3d, 0xee, 0x4a,
+    0x5c, 0x5b, 0x39, 0x44, 0x2d, 0xf6, 0x1a, 0x24,
+    0xda, 0x13, 0xac, 0xab, 0x70, 0xf7, 0x74, 0x40,
+    0x5a, 0x44, 0xfe, 0xc0, 0xc9, 0x26, 0x58, 0x74
+};
+
 const std::string ECDSA_DER("MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAENZpqkPJDj8uhSpffOiCbvSYMLsGB\
 1Eo/WU6mrexjGvduQXjqwon/eSHFI6EgHZk8L9KfiV5XVtVsk2g5wIpJVg==");
 
+const uint8_t ECDSA_DER_KEY_DIGEST[] = {
+  0x1d, 0x20,
+    0xaf, 0x82, 0x3f, 0xfc, 0xdc, 0x85, 0xb2, 0xa4,
+    0xc8, 0xf5, 0x3b, 0x1a, 0xf8, 0xec, 0x4a, 0x55,
+    0x97, 0x55, 0x19, 0x3f, 0x54, 0xdd, 0xd0, 0xfd,
+    0xb5, 0x9d, 0x80, 0x65, 0x80, 0x6b, 0x4b, 0x63
+};
+
 BOOST_AUTO_TEST_CASE(RSA)
 {
   using namespace CryptoPP;
@@ -53,6 +70,13 @@
                                                                          os.buf()->size())));
 
   BOOST_CHECK_EQUAL(publicKey->getKeyType(), KEY_TYPE_RSA);
+
+  Block digestBlock(RSA_DER_KEY_DIGEST, sizeof(RSA_DER_KEY_DIGEST));
+  const Block& digest = publicKey->computeDigest();
+  BOOST_CHECK_EQUAL_COLLECTIONS(digestBlock.wire(),
+                                digestBlock.wire() + digestBlock.size(),
+                                digest.wire(),
+                                digest.wire() + digest.size());
 }
 
 BOOST_AUTO_TEST_CASE(ECDSA)
@@ -68,8 +92,16 @@
                                                                          os.buf()->size())));
 
   BOOST_CHECK_EQUAL(publicKey->getKeyType(), KEY_TYPE_ECDSA);
+
+  Block digestBlock(ECDSA_DER_KEY_DIGEST, sizeof(ECDSA_DER_KEY_DIGEST));
+  const Block& digest = publicKey->computeDigest();
+  BOOST_CHECK_EQUAL_COLLECTIONS(digestBlock.wire(),
+                                digestBlock.wire() + digestBlock.size(),
+                                digest.wire(),
+                                digest.wire() + digest.size());
 }
 
+
 BOOST_AUTO_TEST_SUITE_END()
 
 } // namespace ndn