Add receiver authentication steps

This change adds the necessary crypto + messaging steps for a Cast
receiver to authenticate itself as such.  It also adds an integration
test that checks our sender authentication code against this receiver
authentication code.

Bug: openscreen:91
Change-Id: If298b8781bc95116714eb36fa68ef96ba82742a3
Reviewed-on: https://chromium-review.googlesource.com/c/openscreen/+/1954745
Commit-Queue: Brandon Tolsch <btolsch@chromium.org>
Reviewed-by: mark a. foltz <mfoltz@chromium.org>

4 files changed, 77 insertions, 16 deletions

diff --git a/cast/sender/BUILD.gn b/cast/sender/BUILD.gn
index f42d555c..ae36bf27 100644
--- a/cast/sender/BUILD.gn
+++ b/cast/sender/BUILD.gn
@@ -22,6 +22,8 @@ source_set("channel") {
   public_deps = [
     "../../platform",
     "../../third_party/boringssl",
+    "../common:certificate",
+    "../common:channel",
   ]
 }
 
@@ -34,6 +36,7 @@ source_set("unittests") {
   deps = [
     ":channel",
     "../../platform",
+    "../../testing/util",
     "../../third_party/googletest:gtest",
     "../common/certificate/proto:certificate_proto",
     "../common/certificate/proto:certificate_unittest_proto",
diff --git a/cast/sender/channel/cast_auth_util.cc b/cast/sender/channel/cast_auth_util.cc
index 90d63f77..44a75b98 100644
--- a/cast/sender/channel/cast_auth_util.cc
+++ b/cast/sender/channel/cast_auth_util.cc
@@ -11,6 +11,7 @@
 #include "cast/common/certificate/cast_cert_validator.h"
 #include "cast/common/certificate/cast_cert_validator_internal.h"
 #include "cast/common/certificate/cast_crl.h"
+#include "cast/common/channel/proto/cast_channel.pb.h"
 #include "platform/api/time.h"
 #include "platform/base/error.h"
 #include "util/logging.h"
@@ -222,18 +223,31 @@ openscreen::Error VerifyTLSCertificateValidity(
   return openscreen::Error::None();
 }
 
-ErrorOr<CastDeviceCertPolicy> AuthenticateChallengeReply(
+ErrorOr<CastDeviceCertPolicy> VerifyCredentialsImpl(
+    const AuthResponse& response,
+    const std::string& signature_input,
+    const certificate::CRLPolicy& crl_policy,
+    certificate::TrustStore* cast_trust_store,
+    certificate::TrustStore* crl_trust_store,
+    const certificate::DateTime& verification_time,
+    bool enforce_sha256_checking);
+
+ErrorOr<CastDeviceCertPolicy> AuthenticateChallengeReplyImpl(
     const CastMessage& challenge_reply,
     X509* peer_cert,
-    const AuthContext& auth_context) {
+    const AuthContext& auth_context,
+    const certificate::CRLPolicy& crl_policy,
+    certificate::TrustStore* cast_trust_store,
+    certificate::TrustStore* crl_trust_store,
+    const certificate::DateTime& verification_time) {
   DeviceAuthMessage auth_message;
   openscreen::Error result = ParseAuthMessage(challenge_reply, &auth_message);
   if (!result.ok()) {
     return result;
   }
 
-  result = VerifyTLSCertificateValidity(
-      peer_cert, openscreen::GetWallTimeSinceUnixEpoch());
+  result = VerifyTLSCertificateValidity(peer_cert,
+                                        DateTimeToSeconds(verification_time));
   if (!result.ok()) {
     return result;
   }
@@ -261,7 +275,35 @@ ErrorOr<CastDeviceCertPolicy> AuthenticateChallengeReply(
   OSP_DCHECK_EQ(actual_size, peer_cert_der.size());
   peer_cert_der.resize(actual_size);
 
-  return VerifyCredentials(response, nonce_response + peer_cert_der);
+  return VerifyCredentialsImpl(response, nonce_response + peer_cert_der,
+                               crl_policy, cast_trust_store, crl_trust_store,
+                               verification_time, false);
+}
+
+ErrorOr<CastDeviceCertPolicy> AuthenticateChallengeReply(
+    const CastMessage& challenge_reply,
+    X509* peer_cert,
+    const AuthContext& auth_context) {
+  certificate::DateTime now = {};
+  OSP_CHECK(certificate::DateTimeFromSeconds(
+      openscreen::GetWallTimeSinceUnixEpoch().count(), &now));
+  certificate::CRLPolicy policy = certificate::CRLPolicy::kCrlOptional;
+  return AuthenticateChallengeReplyImpl(
+      challenge_reply, peer_cert, auth_context, policy,
+      /* cast_trust_store */ nullptr, /* crl_trust_store */ nullptr, now);
+}
+
+ErrorOr<CastDeviceCertPolicy> AuthenticateChallengeReplyForTest(
+    const CastMessage& challenge_reply,
+    X509* peer_cert,
+    const AuthContext& auth_context,
+    certificate::CRLPolicy crl_policy,
+    certificate::TrustStore* cast_trust_store,
+    certificate::TrustStore* crl_trust_store,
+    const certificate::DateTime& verification_time) {
+  return AuthenticateChallengeReplyImpl(
+      challenge_reply, peer_cert, auth_context, crl_policy, cast_trust_store,
+      crl_trust_store, verification_time);
 }
 
 // This function does the following
@@ -301,8 +343,8 @@ ErrorOr<CastDeviceCertPolicy> VerifyCredentialsImpl(
   std::vector<std::string> cert_chain;
   cert_chain.push_back(response.client_auth_certificate());
   cert_chain.insert(cert_chain.end(),
-                    response.intermediate_certificate().begin(),
-                    response.intermediate_certificate().end());
+                    response.intermediate_certificates().begin(),
+                    response.intermediate_certificates().end());
 
   // Parse the CRL.
   std::unique_ptr<certificate::CastCRL> crl;
diff --git a/cast/sender/channel/cast_auth_util.h b/cast/sender/channel/cast_auth_util.h
index 35f1d028..b3ea452f 100644
--- a/cast/sender/channel/cast_auth_util.h
+++ b/cast/sender/channel/cast_auth_util.h
@@ -7,10 +7,10 @@
 
 #include <openssl/x509.h>
 
+#include <chrono>
 #include <string>
 
 #include "cast/common/certificate/cast_cert_validator.h"
-#include "cast/common/channel/proto/cast_channel.pb.h"
 #include "platform/base/error.h"
 
 namespace cast {
@@ -61,6 +61,19 @@ ErrorOr<CastDeviceCertPolicy> AuthenticateChallengeReply(
     X509* peer_cert,
     const AuthContext& auth_context);
 
+// Exposed for testing only.
+//
+// Overloaded version of AuthenticateChallengeReply that allows modifying the
+// crl policy, trust stores, and verification times.
+ErrorOr<CastDeviceCertPolicy> AuthenticateChallengeReplyForTest(
+    const CastMessage& challenge_reply,
+    X509* peer_cert,
+    const AuthContext& auth_context,
+    certificate::CRLPolicy crl_policy,
+    certificate::TrustStore* cast_trust_store,
+    certificate::TrustStore* crl_trust_store,
+    const certificate::DateTime& verification_time);
+
 // Performs a quick check of the TLS certificate for time validity requirements.
 openscreen::Error VerifyTLSCertificateValidity(
     X509* peer_cert,
@@ -77,8 +90,8 @@ ErrorOr<CastDeviceCertPolicy> VerifyCredentials(
 
 // Exposed for testing only.
 //
-// Overloaded version of VerifyCredentials that allows modifying
-// the crl policy, trust stores, and verification times.
+// Overloaded version of VerifyCredentials that allows modifying the crl policy,
+// trust stores, and verification times.
 ErrorOr<CastDeviceCertPolicy> VerifyCredentialsForTest(
     const AuthResponse& response,
     const std::string& signature_input,
diff --git a/cast/sender/channel/cast_auth_util_unittest.cc b/cast/sender/channel/cast_auth_util_unittest.cc
index b8a8e90c..a4b341e2 100644
--- a/cast/sender/channel/cast_auth_util_unittest.cc
+++ b/cast/sender/channel/cast_auth_util_unittest.cc
@@ -13,6 +13,7 @@
 #include "cast/common/channel/proto/cast_channel.pb.h"
 #include "gtest/gtest.h"
 #include "platform/api/time.h"
+#include "testing/util/read_file.h"
 #include "util/logging.h"
 
 namespace cast {
@@ -123,8 +124,9 @@ class CastAuthUtilTest : public testing::Test {
     AuthResponse response;
 
     response.set_client_auth_certificate(chain[0]);
-    for (size_t i = 1; i < chain.size(); ++i)
-      response.add_intermediate_certificate(chain[i]);
+    for (size_t i = 1; i < chain.size(); ++i) {
+      response.add_intermediate_certificates(chain[i]);
+    }
 
     response.set_hash_algorithm(digest_algorithm);
     switch (digest_algorithm) {
@@ -168,7 +170,7 @@ TEST_F(CastAuthUtilTest, VerifySuccess) {
 TEST_F(CastAuthUtilTest, VerifyBadCA) {
   std::string signed_data;
   AuthResponse auth_response = CreateAuthResponse(&signed_data, SHA256);
-  MangleString(auth_response.mutable_intermediate_certificate(0));
+  MangleString(auth_response.mutable_intermediate_certificates(0));
   ErrorOr<CastDeviceCertPolicy> result =
       VerifyCredentials(auth_response, signed_data);
   EXPECT_FALSE(result);
@@ -354,8 +356,9 @@ ErrorOr<CastDeviceCertPolicy> TestVerifyRevocation(
 
   if (certificate_chain.size() > 0) {
     response.set_client_auth_certificate(certificate_chain[0]);
-    for (size_t i = 1; i < certificate_chain.size(); ++i)
-      response.add_intermediate_certificate(certificate_chain[i]);
+    for (size_t i = 1; i < certificate_chain.size(); ++i) {
+      response.add_intermediate_certificates(certificate_chain[i]);
+    }
   }
 
   response.set_crl(crl_bundle);
@@ -447,7 +450,7 @@ bool RunTest(const certificate::DeviceCertTest& test_case) {
 // These tests are generated by a test generator in google3.
 void RunTestSuite(const std::string& test_suite_file_name) {
   std::string testsuite_raw =
-      certificate::testing::ReadEntireFileToString(test_suite_file_name);
+      openscreen::ReadEntireFileToString(test_suite_file_name);
   certificate::DeviceCertTestSuite test_suite;
   EXPECT_TRUE(test_suite.ParseFromString(testsuite_raw));
   uint16_t successes = 0;