diff --git a/tests/unit-tests/security/v2/validation-policy-command-interest.t.cpp b/tests/unit-tests/security/v2/validation-policy-command-interest.t.cpp
index 4a3365c..7bd42ea 100644
--- a/tests/unit-tests/security/v2/validation-policy-command-interest.t.cpp
+++ b/tests/unit-tests/security/v2/validation-policy-command-interest.t.cpp
@@ -90,10 +90,14 @@
 {
   auto i1 = makeCommandInterest(identity);
   VALIDATE_SUCCESS(i1, "Should succeed (within grace period)");
+  VALIDATE_FAILURE(i1, "Should fail (replay attack)");
 
   advanceClocks(5_ms);
   auto i2 = makeCommandInterest(identity);
   VALIDATE_SUCCESS(i2, "Should succeed (timestamp larger than previous)");
+
+  auto i3 =  m_signer.makeCommandInterest(Name(identity.getName()).append("CMD"), signingWithSha256());
+  VALIDATE_FAILURE(i3, "Should fail (Sha256 signature violates policy)");
 }
 
 BOOST_AUTO_TEST_CASE(DataPassthru)
@@ -103,6 +107,20 @@
   VALIDATE_SUCCESS(d1, "Should succeed (fallback on inner validation policy for data)");
 }
 
+using ValidationPolicyAcceptAllCommands = ValidationPolicyCommandInterestFixture<DefaultOptions,
+                                                                                 ValidationPolicyAcceptAll>;
+
+BOOST_FIXTURE_TEST_CASE(SignedWithSha256, ValidationPolicyAcceptAllCommands) // Bug 4635
+{
+  auto i1 = m_signer.makeCommandInterest("/hello/world/CMD", signingWithSha256());
+  VALIDATE_SUCCESS(i1, "Should succeed (within grace period)");
+  VALIDATE_FAILURE(i1, "Should fail (replay attack)");
+
+  advanceClocks(5_ms);
+  auto i2 = m_signer.makeCommandInterest("/hello/world/CMD", signingWithSha256());
+  VALIDATE_SUCCESS(i2, "Should succeed (timestamp larger than previous)");
+}
+
 BOOST_AUTO_TEST_SUITE_END() // Accepts
 
 BOOST_AUTO_TEST_SUITE(Rejects)
diff --git a/tests/unit-tests/security/validator-config.t.cpp b/tests/unit-tests/security/validator-config.t.cpp
index 7dd65f5..3e49d24 100644
--- a/tests/unit-tests/security/validator-config.t.cpp
+++ b/tests/unit-tests/security/validator-config.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2017 Regents of the University of California.
+ * Copyright (c) 2013-2018 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -20,6 +20,7 @@
  */
 
 #include "security/validator-config.hpp"
+#include "security/command-interest-signer.hpp"
 #include "security/v2/certificate-fetcher-offline.hpp"
 #include "util/dummy-client-face.hpp"
 
@@ -126,6 +127,30 @@
 
 BOOST_AUTO_TEST_SUITE_END() // Loads
 
+
+BOOST_FIXTURE_TEST_CASE(ValidateCommandInterestWithDigestSha256, ValidatorConfigFixture) // Bug 4635
+{
+  validator.load(configFile);
+
+  CommandInterestSigner signer(m_keyChain);
+  auto i = signer.makeCommandInterest("/hello/world/CMD", signingWithSha256());
+  size_t nValidated = 0, nFailed = 0;
+
+  validator.validate(i, [&] (auto&&...) { ++nValidated; }, [&] (auto&&...) { ++nFailed; });
+  BOOST_CHECK_EQUAL(nValidated, 1);
+  BOOST_CHECK_EQUAL(nFailed, 0);
+
+  validator.validate(i, [&] (auto&&...) { ++nValidated; }, [&] (auto&&...) { ++nFailed; });
+  BOOST_CHECK_EQUAL(nValidated, 1);
+  BOOST_CHECK_EQUAL(nFailed, 1);
+
+  i = signer.makeCommandInterest("/hello/world/CMD", signingWithSha256());
+  validator.validate(i, [&] (auto&&...) { ++nValidated; }, [&] (auto&&...) { ++nFailed; });
+  BOOST_CHECK_EQUAL(nValidated, 2);
+  BOOST_CHECK_EQUAL(nFailed, 1);
+}
+
+
 BOOST_AUTO_TEST_SUITE_END() // TestValidatorConfig
 BOOST_AUTO_TEST_SUITE_END() // Security