First-stage Provisioning 4.0 client ID encryption

(This is a merge of http://go/wvgerrit/150131 to the Android repo.)

This patch changes the code path in the CDM so that the first-stage
provisioning request for Provisioning 4.0 is always encrypted with the
Widevine service certificate instead of the client-set service
certificate, reflecting that the first-stage provisioning is always
handled by Widevine.

This patch also makes several methods on the ServiceCertificate class
const. This has no impact on their behavior.

Bug: 221443151
Test: prov40 tests
Change-Id: Ide4c3927afadcd45ae7fb629b99e2f55cc29d56e

libwvdrmengine/cdm/core/include/certificate_provisioning.h

@@ -86,7 +86,8 @@ class CertificateProvisioning {
       std::string* default_url);
   CdmResponseType FillEncryptedClientId(
       const std::string& client_token,
-      video_widevine::ProvisioningRequest& provisioning_request);
+      video_widevine::ProvisioningRequest& provisioning_request,
+      const ServiceCertificate& service_certificate);
   CdmResponseType HandleProvisioning40Response(
       wvutil::FileSystem* file_system, const std::string& response_message);
 

libwvdrmengine/cdm/core/include/service_certificate.h

@@ -38,8 +38,8 @@ class ServiceCertificate {
   const std::string& provider_id() const { return provider_id_; }
 
   // Verify the signature for a message.
-  virtual CdmResponseType VerifySignedMessage(const std::string& message,
-                                              const std::string& signature);
+  virtual CdmResponseType VerifySignedMessage(
+      const std::string& message, const std::string& signature) const;
 
   // Encrypt the ClientIdentification message for a provisioning or
   // licensing request.  Encryption is performed using the current
@@ -50,7 +50,7 @@ class ServiceCertificate {
   virtual CdmResponseType EncryptClientId(
       CryptoSession* crypto_session,
       const video_widevine::ClientIdentification* clear_client_id,
-      video_widevine::EncryptedClientIdentification* encrypted_client_id);
+      video_widevine::EncryptedClientIdentification* encrypted_client_id) const;
 
   // Helper methods
   static bool GetRequest(CdmKeyMessage* request);
@@ -63,7 +63,7 @@ class ServiceCertificate {
   // string to contain the decrypted data on return, and may not be null.
   // returns NO_ERROR if successful or an appropriate error code otherwise.
   virtual CdmResponseType EncryptRsaOaep(const std::string& plaintext,
-                                         std::string* ciphertext);
+                                         std::string* ciphertext) const;
 
   // Track whether object holds valid certificate
   bool has_certificate_;

libwvdrmengine/cdm/core/src/certificate_provisioning.cpp

@@ -218,7 +218,8 @@ CdmResponseType CertificateProvisioning::GetProvisioningRequestInternal(
   // Prepare device provisioning request.
   ProvisioningRequest provisioning_request;
 
-  status = FillEncryptedClientId(/*client_token=*/"", provisioning_request);
+  status = FillEncryptedClientId(/*client_token=*/"", provisioning_request,
+                                 *service_certificate_);
   if (status != NO_ERROR) return status;
 
   uint32_t nonce;
@@ -339,24 +340,33 @@ CdmResponseType CertificateProvisioning::GetProvisioning40RequestInternal(
     }
   }
 
+  CdmResponseType status = NO_ERROR;
   if (stored_oem_cert.empty()) {
     // This is the first stage provisioning.
     default_url->assign(kProvisioningServerUrl +
                         kProv40FirstStageServerUrlSuffix);
+
+    // First-stage provisioning always uses the WV production service cert for
+    // encryption.
+    ServiceCertificate wv_service_cert;
+    status = wv_service_cert.Init(kCpProductionServiceCertificate);
+    if (status != NO_ERROR) return status;
+
+    // Since |stored_oem_cert| is empty, the client identification token will be
+    // retrieved from OEMCrypto, which is the BCC in this case.
+    status = FillEncryptedClientId(stored_oem_cert, provisioning_request,
+                                   wv_service_cert);
+    if (status != NO_ERROR) return status;
   } else {
     // This is the second stage provisioning.
     default_url->assign(kProvisioningServerUrl);
+    // Since |stored_oem_cert| is non-empty, it will be used as the client
+    // identification token.
+    status = FillEncryptedClientId(stored_oem_cert, provisioning_request,
+                                   *service_certificate_);
+    if (status != NO_ERROR) return status;
   }
 
-  // If this is the first stage, |stored_oem_cert| remains empty. In this case,
-  // the client identification token will be retrieved from OEMCrypto, which is
-  // the BCC in this case.
-  // If this is the second stage, |stored_oem_cert| is non-empty and will be
-  // used as the client identification token.
-  CdmResponseType status =
-      FillEncryptedClientId(stored_oem_cert, provisioning_request);
-  if (status != NO_ERROR) return status;
-
   std::string public_key;
   std::string public_key_signature;
   provisioning_40_wrapped_private_key_.clear();
@@ -396,8 +406,8 @@ CdmResponseType CertificateProvisioning::GetProvisioning40RequestInternal(
 }
 
 CdmResponseType CertificateProvisioning::FillEncryptedClientId(
-    const std::string& client_token,
-    ProvisioningRequest& provisioning_request) {
+    const std::string& client_token, ProvisioningRequest& provisioning_request,
+    const ServiceCertificate& service_certificate) {
   if (!crypto_session_->IsOpen()) {
     return UNKNOWN_ERROR;
   }
@@ -412,13 +422,13 @@ CdmResponseType CertificateProvisioning::FillEncryptedClientId(
   status = id.Prepare(app_parameter, kEmptyString, &client_id);
   if (status != NO_ERROR) return status;
 
-  if (!service_certificate_->has_certificate()) {
+  if (!service_certificate.has_certificate()) {
     LOGE("Service certificate not staged");
     return CERT_PROVISIONING_EMPTY_SERVICE_CERTIFICATE;
   }
 
   // Encrypt client identification
-  return service_certificate_->EncryptClientId(
+  return service_certificate.EncryptClientId(
       crypto_session_.get(), &client_id,
       provisioning_request.mutable_encrypted_client_id());
 }

libwvdrmengine/cdm/core/src/service_certificate.cpp

@@ -206,7 +206,7 @@ CdmResponseType ServiceCertificate::Init(const std::string& certificate) {
 }
 
 CdmResponseType ServiceCertificate::VerifySignedMessage(
-    const std::string& message, const std::string& signature) {
+    const std::string& message, const std::string& signature) const {
   if (!public_key_) {
     LOGE("Service certificate not set");
     return DEVICE_CERTIFICATE_ERROR_4;
@@ -218,8 +218,8 @@ CdmResponseType ServiceCertificate::VerifySignedMessage(
   return NO_ERROR;
 }
 
-CdmResponseType ServiceCertificate::EncryptRsaOaep(const std::string& plaintext,
-                                                   std::string* ciphertext) {
+CdmResponseType ServiceCertificate::EncryptRsaOaep(
+    const std::string& plaintext, std::string* ciphertext) const {
   if (!public_key_) {
     LOGE("Service certificate not set");
     return DEVICE_CERTIFICATE_ERROR_4;
@@ -233,7 +233,7 @@ CdmResponseType ServiceCertificate::EncryptRsaOaep(const std::string& plaintext,
 
 CdmResponseType ServiceCertificate::EncryptClientId(
     CryptoSession* crypto_session, const ClientIdentification* clear_client_id,
-    EncryptedClientIdentification* encrypted_client_id) {
+    EncryptedClientIdentification* encrypted_client_id) const {
   encrypted_client_id->set_provider_id(provider_id_);
   encrypted_client_id->set_service_certificate_serial_number(serial_number_);