Add DecryptCTR to OEMCrypto Mock

This is a software only implementation of the OEMCrypto library for
testing the rest of the DRM code.  It currently implements the
OEMCrypto_DecrtyptCTR function using a clear key.

I've included the license request code so the rest of the group can
play with it, but I have only tested part of it.

This patch also has some makefiles and an integration testing.  You
should be able to generate the shared library libclearkeydrmengine.so with
cd vendor/widevine/libclearkeydrmengine; mm
You can create some unit test and integration test programs from the
directories:
vendor/widevine/libwvdrmengine/oemcrypto/test
vendor/widevine/libclearkeydrmengine/test
vendor/widevine/libclearkeydrmengine/inttest
vendor/widevine/libclearkeydrmengine/crypto/test

This change also addresses some comments about comments in OEMCryptoDASH.h
which were made in https://googleplex-android-review.googlesource.com/257323

Change-Id: Id6899b9f8d2f09e09be2ea493baa83a6b929073b

libclearkeydrmengine/inttest/ClearKey_test.cpp

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2012 Google Inc. All Rights Reserved.
+
+ * These are one level up from unit tests -- they test the shared
+ * clearkey DRM library and all of its components.
+ * These are similar to the
+ */
+
+#include "WVCreateDrmPluginFactory.h"
+#include "MockOEMCrypto.h"
+#include "media/hardware/CryptoAPI.h"
+#include "media/drm/DrmClientAPI.h"
+#include "gtest/gtest.h"
+#include "stdio.h"
+
+using android::sp;
+using android::status_t;
+
+
+TEST(WVClearIntegrationTest, CreatesObject) {
+    android::DrmPluginFactory* factory = createDrmPluginFactory();
+    EXPECT_NE(static_cast<android::DrmPluginFactory*>(NULL), factory)
+            << "createDrmPluginFactory() returned null";
+}
+
+
+static const uint8_t kWidevineUUID[16] = {
+    0xED,0xEF,0x8B,0xA9,0x79,0xD6,0x4A,0xCE,
+    0xA3,0xC8,0x27,0xDC,0xD5,0x1D,0x21,0xED
+};
+
+static const uint8_t kOldNetflixWidevineUUID[16] = {
+    0x29,0x70,0x1F,0xE4,0x3C,0xC7,0x4A,0x34,
+    0x8C,0x5B,0xAE,0x90,0xC7,0x43,0x9A,0x47
+};
+
+static const uint8_t kUnknownUUID[16] = {
+    0x6A,0x7F,0xAA,0xB0,0x83,0xC7,0x9E,0x20,
+    0x08,0xBC,0xEF,0x32,0x34,0x1A,0x9A,0x26
+};
+
+
+TEST(WVClearIntegrationTest, DecryptsBuffer) {
+    android::DrmPluginFactory* factory = createDrmPluginFactory();
+    android::CryptoPlugin *plugin;
+    const char *sessionId = "fake-session-id";
+
+    status_t result = factory->createCryptoPlugin(kWidevineUUID, sessionId,
+                                                  strlen(sessionId), &plugin);
+
+    EXPECT_EQ(android::OK, result)
+            << "WVDrmPluginFactory returned error from createCryptoPlugin()";
+
+    const size_t count = 751;  // a nice big number, but not too round.
+
+    bool secure = false;
+    uint8_t key[16] = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+                        0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f};
+    uint8_t iv[16]  = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+                        0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f};
+    uint8_t ecount[16];
+    uint8_t ivec[16];
+    unsigned int num = 0;
+    unsigned char indata[count];
+    memset(ecount, 0, 16);
+    memcpy(ivec, iv, 16);
+    memset(indata, 0xAA, count);
+    uint8_t srcPtr[count];
+    AES_KEY aes_key;
+    AES_set_encrypt_key(key, 128, &aes_key);
+    AES_ctr128_encrypt(indata, srcPtr, count, &aes_key, ivec, ecount, &num);
+
+    android::CryptoPlugin::SubSample subSamples;
+    subSamples.mNumBytesOfClearData = 0;
+    subSamples.mNumBytesOfEncryptedData = count;
+    size_t numSubSamples = 1;
+    uint8_t dstPtr[count];
+    memset(dstPtr, 0, count);
+    android::AString *errorDetailMsg=NULL;
+    android::CryptoPlugin::Mode mode = android::CryptoPlugin::kMode_AES_CTR;
+    plugin->decrypt( secure, key, iv, mode, srcPtr, &subSamples,
+                     numSubSamples, dstPtr, errorDetailMsg);
+
+    EXPECT_EQ(0, memcmp(indata, dstPtr, count))
+            << "End-to-End decrypt did not work.";
+
+}