security: rename SignatureSha256 to DigestSha256

Change-Id: Idabb95222d86e2541372593698ed9754156a5df2
diff --git a/tests/unit-tests/security/test-signature-sha256.cpp b/tests/unit-tests/security/test-digest-sha256.cpp
similarity index 95%
rename from tests/unit-tests/security/test-signature-sha256.cpp
rename to tests/unit-tests/security/test-digest-sha256.cpp
index 7aac44e..94ded5b 100644
--- a/tests/unit-tests/security/test-signature-sha256.cpp
+++ b/tests/unit-tests/security/test-digest-sha256.cpp
@@ -29,7 +29,7 @@
 using namespace std;
 namespace ndn {
 
-BOOST_AUTO_TEST_SUITE(SecurityTestSignatureSha256)
+BOOST_AUTO_TEST_SUITE(SecurityTestDigestSha256)
 
 string SHA256_RESULT("a883dafc480d466ee04e0d6da986bd78eb1fdd2178d04693723da3a8f95d42f4");
 
@@ -61,7 +61,7 @@
 
   testData.wireEncode();
 
-  SignatureSha256 sig(testData.getSignature());
+  DigestSha256 sig(testData.getSignature());
 
   BOOST_REQUIRE(Validator::verifySignature(testData, sig));
 }