diff --git a/src/security/security-common.hpp b/src/security/security-common.hpp
index 8594581..542e169 100644
--- a/src/security/security-common.hpp
+++ b/src/security/security-common.hpp
@@ -33,8 +33,16 @@
 const ssize_t POS_RANDOM_VAL = -3;
 const ssize_t POS_TIMESTAMP = -4;
 
+/** \brief minimal number of components for Command Interest
+ *  \sa https://redmine.named-data.net/projects/ndn-cxx/wiki/CommandInterest
+ */
 const size_t MIN_LENGTH = 4;
 
+/** \brief minimal number of components for Signed Interest
+ *  \sa https://redmine.named-data.net/projects/ndn-cxx/wiki/SignedInterest
+ */
+const size_t MIN_LENGTH_SIG_ONLY = 2;
+
 } // namespace signed_interest
 
 enum class KeyType {
diff --git a/src/security/validator.cpp b/src/security/validator.cpp
index 488d0d7..1ef7a05 100644
--- a/src/security/validator.cpp
+++ b/src/security/validator.cpp
@@ -22,8 +22,6 @@
  * @author Jeff Thompson <jefft0@remap.ucla.edu>
  */
 
-#include "common.hpp"
-
 #include "validator.hpp"
 #include "../util/crypto.hpp"
 
@@ -115,27 +113,27 @@
 bool
 Validator::verifySignature(const Interest& interest, const PublicKey& key)
 {
-  const Name& interestName = interest.getName();
+  const Name& name = interest.getName();
 
-  if (interestName.size() < 2)
+  if (name.size() < signed_interest::MIN_LENGTH_SIG_ONLY)
     return false;
 
+  Signature sig;
   try {
-    const Block& nameBlock = interestName.wireEncode();
-
-    Signature sig(interestName[signed_interest::POS_SIG_INFO].blockFromValue(),
-                  interestName[signed_interest::POS_SIG_VALUE].blockFromValue());
-
-    if (!sig.hasKeyLocator())
-      return false;
-
-    return verifySignature(nameBlock.value(),
-                           nameBlock.value_size() - interestName[signed_interest::POS_SIG_VALUE].size(),
-                           sig, key);
+    sig.setInfo(name[signed_interest::POS_SIG_INFO].blockFromValue());
+    sig.setValue(name[signed_interest::POS_SIG_VALUE].blockFromValue());
   }
-  catch (const Block::Error& e) {
+  catch (const tlv::Error&) {
     return false;
   }
+
+  if (!sig.hasKeyLocator())
+    return false;
+
+  const Block& nameWire = name.wireEncode();
+  return verifySignature(nameWire.value(),
+                         nameWire.value_size() - name[signed_interest::POS_SIG_VALUE].size(),
+                         sig, key);
 }
 
 bool
diff --git a/src/security/validator.hpp b/src/security/validator.hpp
index bf8e1ca..1f06c83 100644
--- a/src/security/validator.hpp
+++ b/src/security/validator.hpp
@@ -25,9 +25,6 @@
 #ifndef NDN_SECURITY_VALIDATOR_HPP
 #define NDN_SECURITY_VALIDATOR_HPP
 
-#include "../common.hpp"
-
-#include "../data.hpp"
 #include "../face.hpp"
 #include "public-key.hpp"
 #include "signature-sha256-with-rsa.hpp"
@@ -39,9 +36,7 @@
 namespace ndn {
 
 /**
- * @brief Validator is one of the main classes of the security library.
- *
- * The Validator class provides the interfaces for packet validation.
+ * @brief provides the interfaces for packet validation.
  */
 class Validator
 {
diff --git a/tests/unit-tests/make-interest-data.hpp b/tests/unit-tests/make-interest-data.hpp
index 36c8deb..8dea8bf 100644
--- a/tests/unit-tests/make-interest-data.hpp
+++ b/tests/unit-tests/make-interest-data.hpp
@@ -81,6 +81,30 @@
 lp::Nack
 makeNack(const Name& name, uint32_t nonce, lp::NackReason reason);
 
+/** \brief replace a name component
+ *  \param[inout] name name
+ *  \param index name component index
+ *  \param a arguments to name::Component constructor
+ */
+template<typename...A>
+void
+setNameComponent(Name& name, ssize_t index, const A& ...a)
+{
+  Name name2 = name.getPrefix(index);
+  name2.append(name::Component(a...));
+  name2.append(name.getSubName(name2.size()));
+  name = name2;
+}
+
+template<typename PKT, typename...A>
+void
+setNameComponent(PKT& pkt, ssize_t index, const A& ...a)
+{
+  Name name = pkt.getName();
+  setNameComponent(name, index, a...);
+  pkt.setName(name);
+}
+
 } // namespace tests
 } // namespace ndn
 
diff --git a/tests/unit-tests/security/command-interest-validator.t.cpp b/tests/unit-tests/security/command-interest-validator.t.cpp
index 6173274..9a9d1e8 100644
--- a/tests/unit-tests/security/command-interest-validator.t.cpp
+++ b/tests/unit-tests/security/command-interest-validator.t.cpp
@@ -112,16 +112,6 @@
   unique_ptr<CommandInterestValidator> validator;
 };
 
-template<typename...A>
-void
-setNameComponent(Name& name, ssize_t index, const A& ...a)
-{
-  Name name2 = name.getPrefix(index);
-  name2.append(name::Component(a...));
-  name2.append(name.getSubName(index + 1));
-  name = name2;
-}
-
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_FIXTURE_TEST_SUITE(TestCommandInterestValidator, CommandInterestValidatorFixture)
 
@@ -162,57 +152,47 @@
 BOOST_AUTO_TEST_CASE(BadTimestamp)
 {
   auto i1 = makeCommandInterest();
-  Name n1 = i1->getName();
-  setNameComponent(n1, signed_interest::POS_TIMESTAMP, "not-timestamp");
-  i1->setName(n1);
+  setNameComponent(*i1, signed_interest::POS_TIMESTAMP, "not-timestamp");
   assertReject(*i1, CommandInterestValidator::ErrorCode::BAD_TIMESTAMP);
 }
 
 BOOST_AUTO_TEST_CASE(BadSigInfo)
 {
   auto i1 = makeCommandInterest();
-  Name n1 = i1->getName();
-  setNameComponent(n1, signed_interest::POS_SIG_INFO, "not-SignatureInfo");
-  i1->setName(n1);
+  setNameComponent(*i1, signed_interest::POS_SIG_INFO, "not-SignatureInfo");
   assertReject(*i1, CommandInterestValidator::ErrorCode::BAD_SIG_INFO);
 }
 
 BOOST_AUTO_TEST_CASE(MissingKeyLocator)
 {
   auto i1 = makeCommandInterest();
-  Name n1 = i1->getName();
   SignatureInfo sigInfo;
-  setNameComponent(n1, signed_interest::POS_SIG_INFO,
+  setNameComponent(*i1, signed_interest::POS_SIG_INFO,
                    sigInfo.wireEncode().begin(), sigInfo.wireEncode().end());
-  i1->setName(n1);
   assertReject(*i1, CommandInterestValidator::ErrorCode::MISSING_KEY_LOCATOR);
 }
 
 BOOST_AUTO_TEST_CASE(BadKeyLocatorType)
 {
   auto i1 = makeCommandInterest();
-  Name n1 = i1->getName();
   KeyLocator kl;
   kl.setKeyDigest(makeBinaryBlock(tlv::KeyDigest, "\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD", 8));
   SignatureInfo sigInfo;
   sigInfo.setKeyLocator(kl);
-  setNameComponent(n1, signed_interest::POS_SIG_INFO,
+  setNameComponent(*i1, signed_interest::POS_SIG_INFO,
                    sigInfo.wireEncode().begin(), sigInfo.wireEncode().end());
-  i1->setName(n1);
   assertReject(*i1, CommandInterestValidator::ErrorCode::BAD_KEY_LOCATOR_TYPE);
 }
 
 BOOST_AUTO_TEST_CASE(BadCertName)
 {
   auto i1 = makeCommandInterest();
-  Name n1 = i1->getName();
   KeyLocator kl;
   kl.setName("/bad/cert/name");
   SignatureInfo sigInfo;
   sigInfo.setKeyLocator(kl);
-  setNameComponent(n1, signed_interest::POS_SIG_INFO,
+  setNameComponent(*i1, signed_interest::POS_SIG_INFO,
                    sigInfo.wireEncode().begin(), sigInfo.wireEncode().end());
-  i1->setName(n1);
   assertReject(*i1, CommandInterestValidator::ErrorCode::BAD_CERT_NAME);
 }
 
@@ -265,12 +245,9 @@
   auto i1 = makeCommandInterest(); // signed at 0s
   assertAccept(*i1);
 
-  auto i2 = makeCommandInterest();
-  Name n1 = i1->getName();
-  Name n2 = i2->getName();
-  setNameComponent(n2, signed_interest::POS_TIMESTAMP,
-                   n1[signed_interest::POS_TIMESTAMP]);
-  i2->setName(n2); // signed at 0s
+  auto i2 = makeCommandInterest(); // signed at 0s
+  setNameComponent(*i2, signed_interest::POS_TIMESTAMP,
+                   i1->getName()[signed_interest::POS_TIMESTAMP]);
   assertReject(*i2, CommandInterestValidator::ErrorCode::TIMESTAMP_REORDER);
 
   advanceClocks(time::seconds(2));
@@ -320,10 +297,8 @@
   auto i1 = makeCommandInterest(1); // signed at 0ms
   auto i2 = makeCommandInterest(2); // signed at 0ms
   for (auto interest : {i1, i2}) {
-    Name name = interest->getName();
-    setNameComponent(name, signed_interest::POS_TIMESTAMP,
+    setNameComponent(*interest, signed_interest::POS_TIMESTAMP,
                      name::Component::fromNumber(time::toUnixTimestamp(time::system_clock::now()).count()));
-    interest->setName(name);
   } // ensure timestamps are exactly 0ms
 
   assertAccept(*i1); // verifying at 0ms
diff --git a/tests/unit-tests/security/validator.t.cpp b/tests/unit-tests/security/validator.t.cpp
index dd2ecd1..8fa26ec 100644
--- a/tests/unit-tests/security/validator.t.cpp
+++ b/tests/unit-tests/security/validator.t.cpp
@@ -21,16 +21,16 @@
 
 #include "security/validator-null.hpp"
 #include "security/key-chain.hpp"
-#include "util/time.hpp"
-#include "identity-management-fixture.hpp"
+
 #include "boost-test.hpp"
+#include "identity-management-fixture.hpp"
+#include "../make-interest-data.hpp"
 
 namespace ndn {
 namespace tests {
 
-using std::string;
-
-BOOST_FIXTURE_TEST_SUITE(SecurityValidator, IdentityManagementFixture)
+BOOST_AUTO_TEST_SUITE(Security)
+BOOST_FIXTURE_TEST_SUITE(TestValidator, IdentityManagementFixture)
 
 void
 onValidated(const shared_ptr<const Data>& data)
@@ -39,7 +39,7 @@
 }
 
 void
-onValidationFailed(const shared_ptr<const Data>& data, const string& failureInfo)
+onValidationFailed(const shared_ptr<const Data>& data, const std::string& failureInfo)
 {
   BOOST_CHECK(false);
 }
@@ -236,7 +236,30 @@
   BOOST_CHECK(Validator::verifySignature(*testInterestRsa, rsaCert->getPublicKeyInfo()));
 }
 
-BOOST_AUTO_TEST_SUITE_END()
+BOOST_AUTO_TEST_CASE(MalformedInterestSigInfo)
+{
+  auto interest = make_shared<Interest>("/prefix");
+  m_keyChain.sign(*interest);
+
+  setNameComponent(*interest, signed_interest::POS_SIG_INFO, "not-SignatureInfo");
+
+  PublicKey pubkey = m_keyChain.getDefaultCertificate()->getPublicKeyInfo();
+  BOOST_CHECK_EQUAL(Validator::verifySignature(*interest, pubkey), false);
+}
+
+BOOST_AUTO_TEST_CASE(MalformedInterestSigValue)
+{
+  auto interest = make_shared<Interest>("/prefix");
+  m_keyChain.sign(*interest);
+
+  setNameComponent(*interest, signed_interest::POS_SIG_VALUE, "bad-signature-bits");
+
+  PublicKey pubkey = m_keyChain.getDefaultCertificate()->getPublicKeyInfo();
+  BOOST_CHECK_EQUAL(Validator::verifySignature(*interest, pubkey), false);
+}
+
+BOOST_AUTO_TEST_SUITE_END() // TestValidator
+BOOST_AUTO_TEST_SUITE_END() // Security
 
 } // namespace tests
 } // namespace ndn