From 98532d313b66562d44b1aa33f7777f9cbcd09a54 Mon Sep 17 00:00:00 2001
From: Fred Gylys-Colwell <fredgc@google.com>
Date: Tue, 8 May 2018 14:01:45 -0700
Subject: [PATCH] Use 128 bit AES for key control block

Merge from Widevine repo of http://go/wvgerrit/49805

This aligns the oemcrypto reference code and unit tests to match the
API design doc: http://go/oemcrypto

bug: 79375509
test: unit tests pass
Change-Id: I13761a7384a17e99d88e61aaf80b4a22941fd172
---
 .../oemcrypto/mock/src/oemcrypto_session.cpp          |  5 +----
 libwvdrmengine/oemcrypto/test/oec_session_util.cpp    | 11 ++++-------
 libwvdrmengine/oemcrypto/test/oec_session_util.h      |  4 ----
 3 files changed, 5 insertions(+), 15 deletions(-)

diff --git a/libwvdrmengine/oemcrypto/mock/src/oemcrypto_session.cpp b/libwvdrmengine/oemcrypto/mock/src/oemcrypto_session.cpp
index 40983781..4894cd99 100644
--- a/libwvdrmengine/oemcrypto/mock/src/oemcrypto_session.cpp
+++ b/libwvdrmengine/oemcrypto/mock/src/oemcrypto_session.cpp
@@ -749,10 +749,7 @@ OEMCryptoResult SessionContext::InstallKey(
     return OEMCrypto_ERROR_INVALID_CONTEXT;
   }
   if (!DecryptMessage(content_key, key_control_iv, key_control,
-                      &key_control_str,
-                      (session_keys_->type() == OEMCrypto_EntitlementLicense
-                           ? 256
-                           : 128) /* key size */)) {
+                      &key_control_str, 128 /* key size */)) {
     LOGE("[Installkey(): ERROR: Could not decrypt content key]");
     return OEMCrypto_ERROR_UNKNOWN_FAILURE;
   }
diff --git a/libwvdrmengine/oemcrypto/test/oec_session_util.cpp b/libwvdrmengine/oemcrypto/test/oec_session_util.cpp
index a3fa9f0e..75c461dc 100644
--- a/libwvdrmengine/oemcrypto/test/oec_session_util.cpp
+++ b/libwvdrmengine/oemcrypto/test/oec_session_util.cpp
@@ -107,9 +107,9 @@ Session::Session()
       enc_key_(wvcdm::KEY_SIZE),
       public_rsa_(0),
       message_size_(sizeof(MessageData)),
-      num_keys_(4),  // Most tests only use 4 keys.
-      // Other tests will explicitly call set_num_keys.
-      has_entitlement_license_(false) {
+      // Most tests only use 4 keys. Other tests will explicitly call
+      // set_num_keys.
+      num_keys_(4) {
   // Stripe the padded message.
   for (size_t i = 0; i < sizeof(padded_message_.padding); i++) {
     padded_message_.padding[i] = i % 0x100;
@@ -313,7 +313,6 @@ void Session::LoadEnitlementTestKeys(const std::string& pst,
 }
 
 void Session::FillEntitledKeyArray() {
-  has_entitlement_license_ = true;
   for (size_t i = 0; i < num_keys_; ++i) {
     EntitledContentKeyData* key_data = &entitled_key_data_[i];
 
@@ -518,7 +517,6 @@ void Session::FillSimpleMessage(uint32_t duration, uint32_t control,
 void Session::FillSimpleEntitlementMessage(
     uint32_t duration, uint32_t control, uint32_t nonce,
     const std::string& pst) {
-  has_entitlement_license_ = true;
   EXPECT_EQ(
       1, GetRandBytes(license_.mac_key_iv, sizeof(license_.mac_key_iv)));
   EXPECT_EQ(1, GetRandBytes(license_.mac_keys, sizeof(license_.mac_keys)));
@@ -599,10 +597,9 @@ void Session::EncryptAndSign() {
   AES_cbc_encrypt(&license_.mac_keys[0], &encrypted_license().mac_keys[0],
                   2 * wvcdm::MAC_KEY_SIZE, &aes_key, iv_buffer, AES_ENCRYPT);
 
-  int key_size = has_entitlement_license() ? 256 : 128;
   for (unsigned int i = 0; i < num_keys_; i++) {
     memcpy(iv_buffer, &license_.keys[i].control_iv[0], wvcdm::KEY_IV_SIZE);
-    AES_set_encrypt_key(&license_.keys[i].key_data[0], key_size, &aes_key);
+    AES_set_encrypt_key(&license_.keys[i].key_data[0], 128, &aes_key);
     AES_cbc_encrypt(
         reinterpret_cast<const uint8_t*>(&license_.keys[i].control),
         reinterpret_cast<uint8_t*>(&encrypted_license().keys[i].control),
diff --git a/libwvdrmengine/oemcrypto/test/oec_session_util.h b/libwvdrmengine/oemcrypto/test/oec_session_util.h
index 05c9eff3..cea7d8dc 100644
--- a/libwvdrmengine/oemcrypto/test/oec_session_util.h
+++ b/libwvdrmengine/oemcrypto/test/oec_session_util.h
@@ -378,9 +378,6 @@ class Session {
   // The size of the encrypted message.
   size_t message_size() { return message_size_; }
 
-  // If this session has an entitlement license.
-  bool has_entitlement_license() const { return has_entitlement_license_; }
-
  private:
   // Generate mac and enc keys give the master key.
   void DeriveKeys(const uint8_t* master_key,
@@ -410,7 +407,6 @@ class Session {
   vector<uint8_t> encrypted_usage_entry_;
   uint32_t usage_entry_number_;
   string pst_;
-  bool has_entitlement_license_;
 
   // Clear Entitlement key data. This is the backing data for
   // |entitled_key_array_|.