diff --git a/payload_signer_unittest.cc b/payload_signer_unittest.cc
index ff31f02..8121cae 100644
--- a/payload_signer_unittest.cc
+++ b/payload_signer_unittest.cc
@@ -19,50 +19,62 @@
 namespace chromeos_update_engine {
 
 const char* kUnittestPrivateKeyPath = "unittest_key.pem";
+const char* kUnittestPublicKeyPath = "unittest_key.pub.pem";
+
+// Some data and its corresponding hash and signature:
+const char kDataToSign[] = "This is some data to sign.";
+const char kDataHash[] = {
+  0x7a, 0x07, 0xa6, 0x44, 0x08, 0x86, 0x20, 0xa6,
+  0xc1, 0xf8, 0xd9, 0x02, 0x05, 0x63, 0x0d, 0xb7,
+  0xfc, 0x2b, 0xa0, 0xa9, 0x7c, 0x9d, 0x1d, 0x8c,
+  0x01, 0xf5, 0x78, 0x6d, 0xc5, 0x11, 0xb4, 0x06
+};
+const char kDataSignature[] = {
+  0xa4, 0xbc, 0x8f, 0xeb, 0x81, 0x05, 0xaa, 0x56,
+  0x1b, 0x56, 0xe5, 0xcb, 0x9b, 0x1a, 0x00, 0xd7,
+  0x1d, 0x87, 0x8e, 0xda, 0x5e, 0x90, 0x09, 0xb8,
+  0x15, 0xf4, 0x25, 0x97, 0x2f, 0x3c, 0xa1, 0xf3,
+  0x02, 0x75, 0xcd, 0x67, 0x4b, 0x0c, 0x1f, 0xf5,
+  0x6e, 0xf1, 0x58, 0xd7, 0x0d, 0x8c, 0x18, 0x91,
+  0x52, 0x30, 0x98, 0x64, 0x58, 0xc0, 0xe2, 0xb5,
+  0x77, 0x3b, 0x96, 0x8f, 0x05, 0xc4, 0x7f, 0x7a,
+  0x9a, 0x44, 0x0f, 0xc7, 0x1b, 0x90, 0x83, 0xf8,
+  0x69, 0x05, 0xa8, 0x02, 0x57, 0xcd, 0x2e, 0x5b,
+  0x96, 0xc7, 0x77, 0xa6, 0x1f, 0x97, 0x97, 0x05,
+  0xb3, 0x30, 0x1c, 0x27, 0xd7, 0x2d, 0x31, 0x60,
+  0x84, 0x7e, 0x99, 0x00, 0xe6, 0xe1, 0x39, 0xa6,
+  0xf3, 0x3a, 0x72, 0xba, 0xc4, 0xfe, 0x68, 0xa9,
+  0x08, 0xfa, 0xbc, 0xa8, 0x44, 0x66, 0xa0, 0x60,
+  0xde, 0xc9, 0xb2, 0xba, 0xbc, 0x80, 0xb5, 0x55
+};
 
 //class PayloadSignerTest : public ::testing::Test {};
 
-TEST(PayloadSignerTest, SimpleTest) {
-  // Some data and its corresponding signature:
-  const string kDataToSign = "This is some data to sign.";
-  const char kExpectedSignature[] = {
-    0xa4, 0xbc, 0x8f, 0xeb, 0x81, 0x05, 0xaa, 0x56,
-    0x1b, 0x56, 0xe5, 0xcb, 0x9b, 0x1a, 0x00, 0xd7,
-    0x1d, 0x87, 0x8e, 0xda, 0x5e, 0x90, 0x09, 0xb8,
-    0x15, 0xf4, 0x25, 0x97, 0x2f, 0x3c, 0xa1, 0xf3,
-    0x02, 0x75, 0xcd, 0x67, 0x4b, 0x0c, 0x1f, 0xf5,
-    0x6e, 0xf1, 0x58, 0xd7, 0x0d, 0x8c, 0x18, 0x91,
-    0x52, 0x30, 0x98, 0x64, 0x58, 0xc0, 0xe2, 0xb5,
-    0x77, 0x3b, 0x96, 0x8f, 0x05, 0xc4, 0x7f, 0x7a,
-    0x9a, 0x44, 0x0f, 0xc7, 0x1b, 0x90, 0x83, 0xf8,
-    0x69, 0x05, 0xa8, 0x02, 0x57, 0xcd, 0x2e, 0x5b,
-    0x96, 0xc7, 0x77, 0xa6, 0x1f, 0x97, 0x97, 0x05,
-    0xb3, 0x30, 0x1c, 0x27, 0xd7, 0x2d, 0x31, 0x60,
-    0x84, 0x7e, 0x99, 0x00, 0xe6, 0xe1, 0x39, 0xa6,
-    0xf3, 0x3a, 0x72, 0xba, 0xc4, 0xfe, 0x68, 0xa9,
-    0x08, 0xfa, 0xbc, 0xa8, 0x44, 0x66, 0xa0, 0x60,
-    0xde, 0xc9, 0xb2, 0xba, 0xbc, 0x80, 0xb5, 0x55
-  };
-
+namespace {
+void SignSampleData(vector<char>* out_signature_blob) {
   string data_path;
   ASSERT_TRUE(
       utils::MakeTempFile("/tmp/data.XXXXXX", &data_path, NULL));
   ScopedPathUnlinker data_path_unlinker(data_path);
   ASSERT_TRUE(utils::WriteFile(data_path.c_str(),
-                               kDataToSign.data(),
-                               kDataToSign.size()));
+                               kDataToSign,
+                               strlen(kDataToSign)));
   uint64_t length = 0;
   EXPECT_TRUE(PayloadSigner::SignatureBlobLength(kUnittestPrivateKeyPath,
                                                  &length));
   EXPECT_GT(length, 0);
-  vector<char> signature_blob;
   EXPECT_TRUE(PayloadSigner::SignPayload(data_path,
                                          kUnittestPrivateKeyPath,
-                                         &signature_blob));
-  EXPECT_EQ(length, signature_blob.size());
+                                         out_signature_blob));
+  EXPECT_EQ(length, out_signature_blob->size());
+}
+}
+
+TEST(PayloadSignerTest, SimpleTest) {
+  vector<char> signature_blob;
+  SignSampleData(&signature_blob);
 
   // Check the signature itself
-
   Signatures signatures;
   EXPECT_TRUE(signatures.ParseFromArray(&signature_blob[0],
                                         signature_blob.size()));
@@ -70,9 +82,23 @@
   const Signatures_Signature& signature = signatures.signatures(0);
   EXPECT_EQ(kSignatureMessageVersion, signature.version());
   const string sig_data = signature.data();
-  ASSERT_EQ(sizeof(kExpectedSignature), sig_data.size());
-  for (size_t i = 0; i < sizeof(kExpectedSignature); i++) {
-    EXPECT_EQ(kExpectedSignature[i], sig_data[i]);
+  ASSERT_EQ(arraysize(kDataSignature), sig_data.size());
+  for (size_t i = 0; i < arraysize(kDataSignature); i++) {
+    EXPECT_EQ(kDataSignature[i], sig_data[i]);
+  }
+}
+
+TEST(PayloadSignerTest, RunAsRootVerifySignatureTest) {
+  vector<char> signature_blob;
+  SignSampleData(&signature_blob);
+
+  vector<char> hash_data;
+  EXPECT_TRUE(PayloadSigner::VerifySignature(signature_blob,
+                                             kUnittestPublicKeyPath,
+                                             &hash_data));
+  ASSERT_EQ(arraysize(kDataHash), hash_data.size());
+  for (size_t i = 0; i < arraysize(kDataHash); i++) {
+    EXPECT_EQ(kDataHash[i], hash_data[i]);
   }
 }