Handle expired platform key certificates.

Platform keys and certificates are retained until they are manually
cleared or the account is removed from the device.  If a certificate
expires, a new key is now generated and certified as a replacement.

BUG=chromium:322683
TEST=unit

Review URL: https://codereview.chromium.org/110883010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240622 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 173 insertions, 83 deletions

diff --git a/chrome/browser/chromeos/attestation/attestation_policy_observer_unittest.cc b/chrome/browser/chromeos/attestation/attestation_policy_observer_unittest.cc
index 1268d10..31037da 100644
--- a/chrome/browser/chromeos/attestation/attestation_policy_observer_unittest.cc
+++ b/chrome/browser/chromeos/attestation/attestation_policy_observer_unittest.cc
@@ -9,6 +9,7 @@
 #include "base/run_loop.h"
 #include "chrome/browser/chromeos/attestation/attestation_key_payload.pb.h"
 #include "chrome/browser/chromeos/attestation/attestation_policy_observer.h"
+#include "chrome/browser/chromeos/attestation/fake_certificate.h"
 #include "chrome/browser/chromeos/settings/cros_settings.h"
 #include "chrome/browser/chromeos/settings/device_settings_service.h"
 #include "chrome/browser/chromeos/settings/stub_cros_settings_provider.h"
@@ -17,9 +18,6 @@
 #include "chromeos/settings/cros_settings_names.h"
 #include "components/policy/core/common/cloud/mock_cloud_policy_client.h"
 #include "content/public/test/test_browser_thread.h"
-#include "crypto/rsa_private_key.h"
-#include "net/cert/x509_certificate.h"
-#include "net/cert/x509_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using testing::_;
@@ -32,38 +30,9 @@ namespace attestation {
 
 namespace {
 
-// A test key encoded as ASN.1 PrivateKeyInfo from PKCS #8.
-const uint8 kTestKeyData[] = {
-    0x30, 0x82, 0x01, 0x55, 0x02, 0x01, 0x00, 0x30, 0x0d, 0x06, 0x09, 0x2a,
-    0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x01, 0x05, 0x00, 0x04, 0x82,
-    0x01, 0x3f, 0x30, 0x82, 0x01, 0x3b, 0x02, 0x01, 0x00, 0x02, 0x41, 0x00,
-    0xd9, 0xcd, 0xca, 0xcd, 0xc3, 0xea, 0xbe, 0x72, 0x79, 0x1c, 0x29, 0x37,
-    0x39, 0x99, 0x1f, 0xd4, 0xb3, 0x0e, 0xf0, 0x7b, 0x78, 0x77, 0x0e, 0x05,
-    0x3b, 0x65, 0x34, 0x12, 0x62, 0xaf, 0xa6, 0x8d, 0x33, 0xce, 0x78, 0xf8,
-    0x47, 0x05, 0x1d, 0x98, 0xaa, 0x1b, 0x1f, 0x50, 0x05, 0x5b, 0x3c, 0x19,
-    0x3f, 0x80, 0x83, 0x63, 0x63, 0x3a, 0xec, 0xcb, 0x2e, 0x90, 0x4f, 0xf5,
-    0x26, 0x76, 0xf1, 0xd5, 0x02, 0x03, 0x01, 0x00, 0x01, 0x02, 0x40, 0x64,
-    0x29, 0xc2, 0xd9, 0x6b, 0xfe, 0xf9, 0x84, 0x75, 0x73, 0xe0, 0xf4, 0x77,
-    0xb5, 0x96, 0xb0, 0xdf, 0x83, 0xc0, 0x4e, 0x57, 0xf1, 0x10, 0x6e, 0x91,
-    0x89, 0x12, 0x30, 0x5e, 0x57, 0xff, 0x14, 0x59, 0x5f, 0x18, 0x86, 0x4e,
-    0x4b, 0x17, 0x56, 0xfc, 0x8d, 0x40, 0xdd, 0x74, 0x65, 0xd3, 0xff, 0x67,
-    0x64, 0xcb, 0x9c, 0xb4, 0x14, 0x8a, 0x06, 0xb7, 0x13, 0x45, 0x94, 0x16,
-    0x7d, 0x3f, 0xe1, 0x02, 0x21, 0x00, 0xf6, 0x0f, 0x31, 0x6d, 0x06, 0xcc,
-    0x3b, 0xa0, 0x44, 0x1f, 0xf5, 0xc2, 0x45, 0x2b, 0x10, 0x6c, 0xf9, 0x6f,
-    0x8f, 0x87, 0x3d, 0xc0, 0x3b, 0x55, 0x13, 0x37, 0x80, 0xcd, 0x9f, 0xe1,
-    0xb7, 0xd9, 0x02, 0x21, 0x00, 0xe2, 0x9a, 0x5f, 0xbf, 0x95, 0x74, 0xb5,
-    0x7a, 0x6a, 0xa6, 0x97, 0xbd, 0x75, 0x8c, 0x97, 0x18, 0x24, 0xd6, 0x09,
-    0xcd, 0xdc, 0xb5, 0x94, 0xbf, 0xe2, 0x78, 0xaa, 0x20, 0x47, 0x9f, 0x68,
-    0x5d, 0x02, 0x21, 0x00, 0xaf, 0x8f, 0x97, 0x8c, 0x5a, 0xd5, 0x4d, 0x95,
-    0xc4, 0x05, 0xa9, 0xab, 0xba, 0xfe, 0x46, 0xf1, 0xf9, 0xe7, 0x07, 0x59,
-    0x4f, 0x4d, 0xe1, 0x07, 0x8a, 0x76, 0x87, 0x88, 0x2f, 0x13, 0x35, 0xc1,
-    0x02, 0x20, 0x24, 0xc3, 0xd9, 0x2f, 0x13, 0x47, 0x99, 0x3e, 0x20, 0x59,
-    0xa1, 0x1a, 0xeb, 0x1c, 0x81, 0x53, 0x38, 0x7e, 0xc5, 0x9e, 0x71, 0xe5,
-    0xc0, 0x19, 0x95, 0xdb, 0xef, 0xf6, 0x46, 0xc8, 0x95, 0x3d, 0x02, 0x21,
-    0x00, 0xaa, 0xb1, 0xff, 0x8a, 0xa2, 0xb2, 0x2b, 0xef, 0x9a, 0x83, 0x3f,
-    0xc5, 0xbc, 0xd4, 0x6a, 0x07, 0xe8, 0xc7, 0x0b, 0x2e, 0xd4, 0x0f, 0xf8,
-    0x98, 0x68, 0xe1, 0x04, 0xa8, 0x92, 0xd0, 0x10, 0xaa,
-};
+const int64 kCertValid = 90;
+const int64 kCertExpiringSoon = 20;
+const int64 kCertExpired = -20;
 
 void DBusCallbackFalse(const BoolDBusMethodCallback& callback) {
   base::MessageLoop::current()->PostTask(
@@ -130,12 +99,6 @@ class AttestationPolicyObserverTest : public ::testing::Test {
   }
 
  protected:
-  enum CertExpiryOptions {
-    CERT_VALID,
-    CERT_EXPIRING_SOON,
-    CERT_EXPIRED
-  };
-
   enum MockOptions {
     MOCK_KEY_EXISTS = 1,          // Configure so a certified key exists.
     MOCK_KEY_UPLOADED = (1 << 1), // Configure so an upload has occurred.
@@ -204,37 +167,6 @@ class AttestationPolicyObserverTest : public ::testing::Test {
     return serialized;
   }
 
-  bool CreateCertificate(CertExpiryOptions options, std::string* certificate) {
-    base::Time valid_start = base::Time::Now() - base::TimeDelta::FromDays(90);
-    base::Time valid_expiry;
-    switch (options) {
-      case CERT_VALID:
-        valid_expiry = base::Time::Now() + base::TimeDelta::FromDays(90);
-        break;
-      case CERT_EXPIRING_SOON:
-        valid_expiry = base::Time::Now() + base::TimeDelta::FromDays(20);
-        break;
-      case CERT_EXPIRED:
-        valid_expiry = base::Time::Now() - base::TimeDelta::FromDays(20);
-        break;
-      default:
-        NOTREACHED();
-    }
-    scoped_ptr<crypto::RSAPrivateKey> test_key(
-        crypto::RSAPrivateKey::CreateFromPrivateKeyInfo(
-            std::vector<uint8>(&kTestKeyData[0],
-                               &kTestKeyData[arraysize(kTestKeyData)])));
-    if (!test_key.get())
-      return false;
-    return net::x509_util::CreateSelfSignedCert(test_key.get(),
-                                                net::x509_util::DIGEST_SHA256,
-                                                "CN=subject",
-                                                12345,
-                                                valid_start,
-                                                valid_expiry,
-                                                certificate);
-  }
-
   base::MessageLoop message_loop_;
   content::TestBrowserThread ui_thread_;
   ScopedTestDeviceSettingsService test_device_settings_service_;
@@ -264,28 +196,32 @@ TEST_F(AttestationPolicyObserverTest, NewCertificate) {
 
 TEST_F(AttestationPolicyObserverTest, KeyExistsNotUploaded) {
   std::string certificate;
-  ASSERT_TRUE(CreateCertificate(CERT_VALID, &certificate));
+  ASSERT_TRUE(GetFakeCertificate(base::TimeDelta::FromDays(kCertValid),
+                                 &certificate));
   SetupMocks(MOCK_KEY_EXISTS, certificate);
   Run();
 }
 
 TEST_F(AttestationPolicyObserverTest, KeyExistsAlreadyUploaded) {
   std::string certificate;
-  ASSERT_TRUE(CreateCertificate(CERT_VALID, &certificate));
+  ASSERT_TRUE(GetFakeCertificate(base::TimeDelta::FromDays(kCertValid),
+                                 &certificate));
   SetupMocks(MOCK_KEY_EXISTS | MOCK_KEY_UPLOADED, certificate);
   Run();
 }
 
 TEST_F(AttestationPolicyObserverTest, KeyExistsCertExpiringSoon) {
   std::string certificate;
-  ASSERT_TRUE(CreateCertificate(CERT_EXPIRING_SOON, &certificate));
+  ASSERT_TRUE(GetFakeCertificate(base::TimeDelta::FromDays(kCertExpiringSoon),
+                                 &certificate));
   SetupMocks(MOCK_KEY_EXISTS | MOCK_KEY_UPLOADED | MOCK_NEW_KEY, certificate);
   Run();
 }
 
 TEST_F(AttestationPolicyObserverTest, KeyExistsCertExpired) {
   std::string certificate;
-  ASSERT_TRUE(CreateCertificate(CERT_EXPIRED, &certificate));
+  ASSERT_TRUE(GetFakeCertificate(base::TimeDelta::FromDays(kCertExpired),
+                                 &certificate));
   SetupMocks(MOCK_KEY_EXISTS | MOCK_KEY_UPLOADED | MOCK_NEW_KEY, certificate);
   Run();
 }
diff --git a/chrome/browser/chromeos/attestation/fake_certificate.cc b/chrome/browser/chromeos/attestation/fake_certificate.cc
new file mode 100644
index 0000000..b1e8a82
--- /dev/null
+++ b/chrome/browser/chromeos/attestation/fake_certificate.cc
@@ -0,0 +1,74 @@
+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "fake_certificate.h"
+
+#include "base/time/time.h"
+#include "crypto/rsa_private_key.h"
+#include "net/cert/x509_certificate.h"
+#include "net/cert/x509_util.h"
+
+namespace chromeos {
+namespace attestation {
+
+namespace {
+
+// A test key encoded as ASN.1 PrivateKeyInfo from PKCS #8.
+const uint8 kTestKeyData[] = {
+    0x30, 0x82, 0x01, 0x55, 0x02, 0x01, 0x00, 0x30, 0x0d, 0x06, 0x09, 0x2a,
+    0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x01, 0x05, 0x00, 0x04, 0x82,
+    0x01, 0x3f, 0x30, 0x82, 0x01, 0x3b, 0x02, 0x01, 0x00, 0x02, 0x41, 0x00,
+    0xd9, 0xcd, 0xca, 0xcd, 0xc3, 0xea, 0xbe, 0x72, 0x79, 0x1c, 0x29, 0x37,
+    0x39, 0x99, 0x1f, 0xd4, 0xb3, 0x0e, 0xf0, 0x7b, 0x78, 0x77, 0x0e, 0x05,
+    0x3b, 0x65, 0x34, 0x12, 0x62, 0xaf, 0xa6, 0x8d, 0x33, 0xce, 0x78, 0xf8,
+    0x47, 0x05, 0x1d, 0x98, 0xaa, 0x1b, 0x1f, 0x50, 0x05, 0x5b, 0x3c, 0x19,
+    0x3f, 0x80, 0x83, 0x63, 0x63, 0x3a, 0xec, 0xcb, 0x2e, 0x90, 0x4f, 0xf5,
+    0x26, 0x76, 0xf1, 0xd5, 0x02, 0x03, 0x01, 0x00, 0x01, 0x02, 0x40, 0x64,
+    0x29, 0xc2, 0xd9, 0x6b, 0xfe, 0xf9, 0x84, 0x75, 0x73, 0xe0, 0xf4, 0x77,
+    0xb5, 0x96, 0xb0, 0xdf, 0x83, 0xc0, 0x4e, 0x57, 0xf1, 0x10, 0x6e, 0x91,
+    0x89, 0x12, 0x30, 0x5e, 0x57, 0xff, 0x14, 0x59, 0x5f, 0x18, 0x86, 0x4e,
+    0x4b, 0x17, 0x56, 0xfc, 0x8d, 0x40, 0xdd, 0x74, 0x65, 0xd3, 0xff, 0x67,
+    0x64, 0xcb, 0x9c, 0xb4, 0x14, 0x8a, 0x06, 0xb7, 0x13, 0x45, 0x94, 0x16,
+    0x7d, 0x3f, 0xe1, 0x02, 0x21, 0x00, 0xf6, 0x0f, 0x31, 0x6d, 0x06, 0xcc,
+    0x3b, 0xa0, 0x44, 0x1f, 0xf5, 0xc2, 0x45, 0x2b, 0x10, 0x6c, 0xf9, 0x6f,
+    0x8f, 0x87, 0x3d, 0xc0, 0x3b, 0x55, 0x13, 0x37, 0x80, 0xcd, 0x9f, 0xe1,
+    0xb7, 0xd9, 0x02, 0x21, 0x00, 0xe2, 0x9a, 0x5f, 0xbf, 0x95, 0x74, 0xb5,
+    0x7a, 0x6a, 0xa6, 0x97, 0xbd, 0x75, 0x8c, 0x97, 0x18, 0x24, 0xd6, 0x09,
+    0xcd, 0xdc, 0xb5, 0x94, 0xbf, 0xe2, 0x78, 0xaa, 0x20, 0x47, 0x9f, 0x68,
+    0x5d, 0x02, 0x21, 0x00, 0xaf, 0x8f, 0x97, 0x8c, 0x5a, 0xd5, 0x4d, 0x95,
+    0xc4, 0x05, 0xa9, 0xab, 0xba, 0xfe, 0x46, 0xf1, 0xf9, 0xe7, 0x07, 0x59,
+    0x4f, 0x4d, 0xe1, 0x07, 0x8a, 0x76, 0x87, 0x88, 0x2f, 0x13, 0x35, 0xc1,
+    0x02, 0x20, 0x24, 0xc3, 0xd9, 0x2f, 0x13, 0x47, 0x99, 0x3e, 0x20, 0x59,
+    0xa1, 0x1a, 0xeb, 0x1c, 0x81, 0x53, 0x38, 0x7e, 0xc5, 0x9e, 0x71, 0xe5,
+    0xc0, 0x19, 0x95, 0xdb, 0xef, 0xf6, 0x46, 0xc8, 0x95, 0x3d, 0x02, 0x21,
+    0x00, 0xaa, 0xb1, 0xff, 0x8a, 0xa2, 0xb2, 0x2b, 0xef, 0x9a, 0x83, 0x3f,
+    0xc5, 0xbc, 0xd4, 0x6a, 0x07, 0xe8, 0xc7, 0x0b, 0x2e, 0xd4, 0x0f, 0xf8,
+    0x98, 0x68, 0xe1, 0x04, 0xa8, 0x92, 0xd0, 0x10, 0xaa,
+};
+
+}  // namespace
+
+bool GetFakeCertificate(const base::TimeDelta& expiry,
+                        std::string* certificate) {
+  base::Time valid_start = base::Time::Now() - base::TimeDelta::FromDays(1);
+  base::Time valid_expiry = base::Time::Now() + expiry;
+  if (valid_expiry <= valid_start)
+    valid_start = valid_expiry - base::TimeDelta::FromDays(1);
+  scoped_ptr<crypto::RSAPrivateKey> test_key(
+      crypto::RSAPrivateKey::CreateFromPrivateKeyInfo(
+          std::vector<uint8>(&kTestKeyData[0],
+                             &kTestKeyData[arraysize(kTestKeyData)])));
+  if (!test_key.get())
+    return false;
+  return net::x509_util::CreateSelfSignedCert(test_key.get(),
+                                              net::x509_util::DIGEST_SHA256,
+                                              "CN=subject",
+                                              12345,
+                                              valid_start,
+                                              valid_expiry,
+                                              certificate);
+}
+
+}  // namespace attestation
+}  // namespace chromeos
diff --git a/chrome/browser/chromeos/attestation/fake_certificate.h b/chrome/browser/chromeos/attestation/fake_certificate.h
new file mode 100644
index 0000000..2979d93
--- /dev/null
+++ b/chrome/browser/chromeos/attestation/fake_certificate.h
@@ -0,0 +1,26 @@
+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_CHROMEOS_ATTESTATION_FAKE_CERTIFICATE_H_
+#define CHROME_BROWSER_CHROMEOS_ATTESTATION_FAKE_CERTIFICATE_H_
+
+#include <string>
+
+#include "base/time/time.h"
+
+namespace chromeos {
+namespace attestation {
+
+// Creates a self-signed |certificate| based on constant key material.  The
+// certificate |expiry| is relative to the current time.  The certificate will
+// be (or have been) valid from sometime before the current time or expiry,
+// whichever is first.  This is designed for use in unit tests and runs quickly.
+// Returns true on success.
+bool GetFakeCertificate(const base::TimeDelta& expiry,
+                        std::string* certificate);
+
+}  // namespace attestation
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_ATTESTATION_FAKE_CERTIFICATE_H_
diff --git a/chrome/browser/chromeos/attestation/platform_verification_flow.cc b/chrome/browser/chromeos/attestation/platform_verification_flow.cc
index f741263..95767a8 100644
--- a/chrome/browser/chromeos/attestation/platform_verification_flow.cc
+++ b/chrome/browser/chromeos/attestation/platform_verification_flow.cc
@@ -31,6 +31,7 @@
 #include "content/public/browser/user_metrics.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/url_constants.h"
+#include "net/cert/x509_certificate.h"
 
 namespace {
 
@@ -143,7 +144,6 @@ void PlatformVerificationFlow::ChallengePlatformKey(
     return;
   }
   if (!IsAttestationEnabled(web_contents)) {
-    LOG(INFO) << "PlatformVerificationFlow: Feature disabled.";
     ReportError(callback, POLICY_REJECTED);
     return;
   }
@@ -208,7 +208,6 @@ void PlatformVerificationFlow::OnConsentResponse(
       return;
     }
     if (consent_response == CONSENT_RESPONSE_DENY) {
-      LOG(INFO) << "PlatformVerificationFlow: User rejected request.";
       content::RecordAction(
           content::UserMetricsAction("PlatformVerificationRejected"));
       ReportError(context.callback, USER_REJECTED);
@@ -228,6 +227,12 @@ void PlatformVerificationFlow::OnConsentResponse(
     return;
   }
 
+  GetCertificate(context, user->email(), false /* Don't force a new key */);
+}
+
+void PlatformVerificationFlow::GetCertificate(const ChallengeContext& context,
+                                              const std::string& user_id,
+                                              bool force_new_key) {
   scoped_ptr<base::Timer> timer(new base::Timer(false,    // Don't retain.
                                                 false));  // Don't repeat.
   base::Closure timeout_callback = base::Bind(
@@ -240,13 +245,13 @@ void PlatformVerificationFlow::OnConsentResponse(
       &PlatformVerificationFlow::OnCertificateReady,
       this,
       context,
-      user->email(),
+      user_id,
       base::Passed(&timer));
   attestation_flow_->GetCertificate(
       PROFILE_CONTENT_PROTECTION_CERTIFICATE,
-      user->email(),
+      user_id,
       context.service_id,
-      false,  // Don't force a new key.
+      force_new_key,
       certificate_callback);
 }
 
@@ -271,6 +276,10 @@ void PlatformVerificationFlow::OnCertificateReady(
     ReportError(context.callback, PLATFORM_NOT_VERIFIED);
     return;
   }
+  if (IsExpired(certificate)) {
+    GetCertificate(context, user_id, true /* Force a new key */);
+    return;
+  }
   cryptohome::AsyncMethodCaller::DataCallback cryptohome_callback = base::Bind(
       &PlatformVerificationFlow::OnChallengeReady,
       this,
@@ -311,7 +320,6 @@ void PlatformVerificationFlow::OnChallengeReady(
                        signed_data_pb.data(),
                        signed_data_pb.signature(),
                        certificate);
-  LOG(INFO) << "PlatformVerificationFlow: Platform successfully verified.";
 }
 
 PrefService* PlatformVerificationFlow::GetPrefs(
@@ -442,5 +450,16 @@ void PlatformVerificationFlow::RecordDomainConsent(
   }
 }
 
+bool PlatformVerificationFlow::IsExpired(const std::string& certificate) {
+  scoped_refptr<net::X509Certificate> x509(
+      net::X509Certificate::CreateFromBytes(certificate.data(),
+                                            certificate.length()));
+  if (!x509.get() || x509->valid_expiry().is_null()) {
+    LOG(WARNING) << "Failed to parse certificate, cannot check expiry.";
+    return false;
+  }
+  return (base::Time::Now() > x509->valid_expiry());
+}
+
 }  // namespace attestation
 }  // namespace chromeos
diff --git a/chrome/browser/chromeos/attestation/platform_verification_flow.h b/chrome/browser/chromeos/attestation/platform_verification_flow.h
index 0e4e169..e21c024 100644
--- a/chrome/browser/chromeos/attestation/platform_verification_flow.h
+++ b/chrome/browser/chromeos/attestation/platform_verification_flow.h
@@ -180,6 +180,15 @@ class PlatformVerificationFlow
                          bool consent_required,
                          ConsentResponse consent_response);
 
+  // Initiates the flow to get a platform key certificate.  The arguments to
+  // ChallengePlatformKey are in |context|.  |user_id| identifies the user for
+  // which to get a certificate.  If |force_new_key| is true then any existing
+  // key for the same user and service will be ignored and a new key will be
+  // generated and certified.
+  void GetCertificate(const ChallengeContext& context,
+                      const std::string& user_id,
+                      bool force_new_key);
+
   // A callback called when an attestation certificate request operation
   // completes.  The arguments to ChallengePlatformKey are in |context|.
   // |user_id| identifies the user for which the certificate was requested.
@@ -252,6 +261,9 @@ class PlatformVerificationFlow
                            const GURL& url,
                            bool allow_domain);
 
+  // Returns true iff |certificate| is an expired X.509 certificate.
+  bool IsExpired(const std::string& certificate);
+
   void set_testing_prefs(PrefService* testing_prefs) {
     testing_prefs_ = testing_prefs;
   }
diff --git a/chrome/browser/chromeos/attestation/platform_verification_flow_unittest.cc b/chrome/browser/chromeos/attestation/platform_verification_flow_unittest.cc
index b817405..a46081d 100644
--- a/chrome/browser/chromeos/attestation/platform_verification_flow_unittest.cc
+++ b/chrome/browser/chromeos/attestation/platform_verification_flow_unittest.cc
@@ -10,6 +10,7 @@
 #include "base/prefs/testing_pref_service.h"
 #include "base/run_loop.h"
 #include "chrome/browser/chromeos/attestation/attestation_signed_data.pb.h"
+#include "chrome/browser/chromeos/attestation/fake_certificate.h"
 #include "chrome/browser/chromeos/attestation/platform_verification_flow.h"
 #include "chrome/browser/chromeos/login/mock_user_manager.h"
 #include "chrome/browser/chromeos/settings/cros_settings.h"
@@ -123,6 +124,7 @@ class PlatformVerificationFlowTest : public ::testing::Test {
       : message_loop_(base::MessageLoop::TYPE_UI),
         ui_thread_(content::BrowserThread::UI, &message_loop_),
         certificate_success_(true),
+        fake_certificate_index_(0),
         sign_challenge_success_(true),
         result_(PlatformVerificationFlow::INTERNAL_ERROR) {}
 
@@ -265,10 +267,14 @@ class PlatformVerificationFlowTest : public ::testing::Test {
 
   void FakeGetCertificate(
       const AttestationFlow::CertificateCallback& callback) {
+    std::string certificate =
+        (fake_certificate_index_ < fake_certificate_list_.size()) ?
+            fake_certificate_list_[fake_certificate_index_] : kTestCertificate;
     base::MessageLoop::current()->PostTask(FROM_HERE,
                                            base::Bind(callback,
                                                       certificate_success_,
-                                                      kTestCertificate));
+                                                      certificate));
+    ++fake_certificate_index_;
   }
 
   void FakeSignChallenge(
@@ -317,6 +323,8 @@ class PlatformVerificationFlowTest : public ::testing::Test {
 
   // Controls result of FakeGetCertificate.
   bool certificate_success_;
+  std::vector<std::string> fake_certificate_list_;
+  size_t fake_certificate_index_;
 
   // Controls result of FakeSignChallenge.
   bool sign_challenge_success_;
@@ -459,5 +467,18 @@ TEST_F(PlatformVerificationFlowTest, Timeout) {
   EXPECT_EQ(PlatformVerificationFlow::TIMEOUT, result_);
 }
 
+TEST_F(PlatformVerificationFlowTest, ExpiredCert) {
+  ExpectAttestationFlow();
+  fake_certificate_list_.resize(2);
+  ASSERT_TRUE(GetFakeCertificate(base::TimeDelta::FromDays(-1),
+                                 &fake_certificate_list_[0]));
+  ASSERT_TRUE(GetFakeCertificate(base::TimeDelta::FromDays(1),
+                                 &fake_certificate_list_[1]));
+  verifier_->ChallengePlatformKey(NULL, kTestID, kTestChallenge, callback_);
+  base::RunLoop().RunUntilIdle();
+  EXPECT_EQ(PlatformVerificationFlow::SUCCESS, result_);
+  EXPECT_EQ(certificate_, fake_certificate_list_[1]);
+}
+
 }  // namespace attestation
 }  // namespace chromeos
diff --git a/chrome/chrome_tests_unit.gypi b/chrome/chrome_tests_unit.gypi
index d07dba3..62789c4 100644
--- a/chrome/chrome_tests_unit.gypi
+++ b/chrome/chrome_tests_unit.gypi
@@ -599,6 +599,8 @@
         'browser/chromeos/accessibility/magnification_manager_unittest.cc',
         'browser/chromeos/attestation/attestation_ca_client_unittest.cc',
         'browser/chromeos/attestation/attestation_policy_observer_unittest.cc',
+        'browser/chromeos/attestation/fake_certificate.cc',
+        'browser/chromeos/attestation/fake_certificate.h',
         'browser/chromeos/attestation/platform_verification_flow_unittest.cc',
         'browser/chromeos/contacts/contact_database_unittest.cc',
         'browser/chromeos/contacts/contact_manager_stub.cc',